USAP-DC

{"dp_type": "Project", "free_text": "Antarctic Circumpolar Current"}

[{"awards": "1558448 Girton, James; 1853291 Girton, James", "bounds_geometry": "POLYGON((-70 -58,-69 -58,-68 -58,-67 -58,-66 -58,-65 -58,-64 -58,-63 -58,-62 -58,-61 -58,-60 -58,-60 -58.8,-60 -59.6,-60 -60.4,-60 -61.2,-60 -62,-60 -62.8,-60 -63.6,-60 -64.4,-60 -65.2,-60 -66,-61 -66,-62 -66,-63 -66,-64 -66,-65 -66,-66 -66,-67 -66,-68 -66,-69 -66,-70 -66,-70 -65.2,-70 -64.4,-70 -63.6,-70 -62.8,-70 -62,-70 -61.2,-70 -60.4,-70 -59.6,-70 -58.8,-70 -58))", "dataset_titles": "Expedition Data; Expedition data of LMG1612; Expedition Data of LMG1612; Expedition Data of LMG1909; LMG2002 Expedtition Data", "datasets": [{"dataset_uid": "200430", "doi": null, "keywords": null, "people": null, "repository": "R2R", "science_program": null, "title": "Expedition Data of LMG1612", "url": "https://www.rvdata.us/search/cruise/NBP1612"}, {"dataset_uid": "200429", "doi": "", "keywords": null, "people": null, "repository": "R2R", "science_program": null, "title": "Expedition data of LMG1612", "url": "https://www.rvdata.us/search/cruise/LMG1612"}, {"dataset_uid": "200222", "doi": "10.7284/908802", "keywords": null, "people": null, "repository": "R2R", "science_program": null, "title": "LMG2002 Expedtition Data", "url": "https://www.rvdata.us/search/cruise/LMG2002"}, {"dataset_uid": "200431", "doi": null, "keywords": null, "people": null, "repository": "R2R", "science_program": null, "title": "Expedition Data of LMG1909", "url": "https://www.rvdata.us/search/cruise/LMG1909"}, {"dataset_uid": "001365", "doi": "", "keywords": null, "people": null, "repository": "R2R", "science_program": null, "title": "Expedition Data", "url": "https://www.rvdata.us/search/cruise/LMG1703"}], "date_created": "Wed, 15 Jan 2025 00:00:00 GMT", "description": "Air-sea interaction in the Southern Ocean connects the \"conveyor belt\" overturning circulations in each the major oceans of the world (Atlantic, Pacific, and Indian), providing the long-term memory of the climate system by determining the rates of oceanic heat and carbon storage over tens to hundreds of years as well as the supply of heat to melt Antarctic ice shelves. With the goal of enhancing our ability to study these air-sea interaction processes through sustained autonomous presence in remote locations, our project conducted two deployments of a wave-propelled robotic surface vehicle (Wave Glider) near Palmer Station for extended missions around Drake Passage and the Antarctic Peninsula. Over 3 months in 2016-17 and 4 months in 2019-20, the Wave Glider conducted time series stations and surveys of the Polar Front (one of the intense jets of the Antarctic Circumpolar Current). The vehicle also collected multiple instances of calibration data by positioning itself near the tracks of passing Antarctic research vessels.\r\n\r\nAlthough these first extended deployments revealed some important limitations in the Wave Glider\u0027s durability and its ability to maintain solar battery charging in the high-latitude Antarctic, the results have laid the groundwork for future Wave Glider missions. The second field season included a new profiling winch system for subsurface temperature and salinity sampling, and although it only survived for a few profiles it demonstrated its potential in addition to clarifying likely failure modes. Subsequent deployments with a smaller self-recording CTD package have been more successful.", "east": -60.0, "geometry": "POINT(-65 -62)", "instruments": "IN SITU/LABORATORY INSTRUMENTS \u003e PHOTON/OPTICAL DETECTORS \u003e CAMERAS \u003e CAMERA; IN SITU/LABORATORY INSTRUMENTS \u003e CURRENT/WIND METERS \u003e SONIC ANEMOMETER; IN SITU/LABORATORY INSTRUMENTS \u003e CURRENT/WIND METERS \u003e CURRENT METERS; EARTH REMOTE SENSING INSTRUMENTS \u003e ACTIVE REMOTE SENSING \u003e PROFILERS/SOUNDERS \u003e ACOUSTIC SOUNDERS \u003e ECHO SOUNDERS; EARTH REMOTE SENSING INSTRUMENTS \u003e PASSIVE REMOTE SENSING \u003e POSITIONING/NAVIGATION \u003e GPS \u003e GPS; IN SITU/LABORATORY INSTRUMENTS \u003e CHEMICAL METERS/ANALYZERS \u003e FLUOROMETERS; IN SITU/LABORATORY INSTRUMENTS \u003e MAGNETIC/MOTION SENSORS \u003e GRAVIMETERS \u003e GRAVIMETERS; IN SITU/LABORATORY INSTRUMENTS \u003e PROFILERS/SOUNDERS \u003e ACOUSTIC SOUNDERS \u003e MBES; IN SITU/LABORATORY INSTRUMENTS \u003e PROFILERS/SOUNDERS \u003e CTD; IN SITU/LABORATORY INSTRUMENTS \u003e PROFILERS/SOUNDERS \u003e THERMOSALINOGRAPHS; IN SITU/LABORATORY INSTRUMENTS \u003e RECORDERS/LOGGERS \u003e AWS", "is_usap_dc": true, "keywords": "SEA SURFACE TEMPERATURE; TURBULENCE; SURFACE PRESSURE; OCEAN MIXED LAYER; LMG1703; Palmer Station; SALINITY/DENSITY; SURFACE WINDS; OCEAN CURRENTS; HEAT FLUX; SURFACE AIR TEMPERATURE; HUMIDITY; Drake Passage; R/V NBP; R/V LMG; Antarctic Peninsula; WIND STRESS", "locations": "Drake Passage; Antarctic Peninsula; Palmer Station", "north": -58.0, "nsf_funding_programs": "Antarctic Ocean and Atmospheric Sciences", "paleo_time": null, "persons": "Girton, James; Thomson, Jim", "platforms": "WATER-BASED PLATFORMS \u003e VESSELS \u003e SURFACE \u003e R/V LMG; WATER-BASED PLATFORMS \u003e VESSELS \u003e SURFACE \u003e R/V NBP", "repo": "R2R", "repositories": "R2R", "science_programs": null, "south": -66.0, "title": "Wave Glider Observations of Surface Fluxes and Mixed-layer Processes in the Southern Ocean", "uid": "p0010493", "west": -70.0}, {"awards": "2001646 Chereskin, Teresa; 1542902 Chereskin, Teresa", "bounds_geometry": "POLYGON((-68 -54,-66.7 -54,-65.4 -54,-64.1 -54,-62.8 -54,-61.5 -54,-60.2 -54,-58.9 -54,-57.6 -54,-56.3 -54,-55 -54,-55 -55,-55 -56,-55 -57,-55 -58,-55 -59,-55 -60,-55 -61,-55 -62,-55 -63,-55 -64,-56.3 -64,-57.6 -64,-58.9 -64,-60.2 -64,-61.5 -64,-62.8 -64,-64.1 -64,-65.4 -64,-66.7 -64,-68 -64,-68 -63,-68 -62,-68 -61,-68 -60,-68 -59,-68 -58,-68 -57,-68 -56,-68 -55,-68 -54))", "dataset_titles": "Joint Archive for shipboard ADCP data; World Ocean Database", "datasets": [{"dataset_uid": "200355", "doi": "", "keywords": null, "people": null, "repository": "NCEI", "science_program": null, "title": "World Ocean Database", "url": "https://www.nodc.noaa.gov/OC5/SELECT/dbsearch/dbsearch.html"}, {"dataset_uid": "200354", "doi": "", "keywords": null, "people": null, "repository": "NCEI", "science_program": null, "title": "Joint Archive for shipboard ADCP data", "url": "https://uhslc.soest.hawaii.edu/sadcp/"}], "date_created": "Fri, 03 Mar 2023 00:00:00 GMT", "description": "The Antarctic Circumpolar Current (ACC) is the largest current on the planet, flowing west to east around Antarctica, forming a barrier that separates warmer waters to the north from colder waters to the south. Ocean eddies (like atmospheric storms) break through the ACC barrier, transferring heat across the ACC towards Antarctica. When warmer ocean waters intrude onto the Antarctic continental shelves, they contribute to glacial melt and ice shelf retreat. Over the past several decades, the Southern Ocean has warmed and winds have increased due to climate change. Somewhat surprisingly the ACC, though pushed by faster winds, has not accelerated; a faster current would present a stronger barrier to heat transfer. Instead, ocean eddies have increased. These eddies are concentrated at 6-7 \"hot spots\". Drake Passage is one of these hot spots. As the narrowest land gap on the entire circumpolar path of the ACC, Drake Passsage is an ideal monitoring spot. However, it is also one of the windiest and roughest stretches of water on the globe. The only ship that crosses Drake Passage year-round is the USAP supply vessel for Palmer Station, making it a unique platform to monitor the currents and temperature with a minimum of personnel and resources. The Drake Passage time series of upper ocean currents and temperature is now in its 24th year. The upper ocean temperature measurements have found significant warming in Drake Passage. The upper ocean current measurements have confirmed that the ACC has remained steady on average but have also revealed a complicated filamented current structure. Combining temperature and current measurements has provided a better understanding of heat transfer across the ACC by eddies. The time series has also provided valuable ground-truth for satellite measurements and for numerical model predictions looking at the entire ACC. Our studies are focused on examining low-frequency variability - seasonal, interannual, and decadal - in order to provide baselines from which to evaluate and interpret physical and biogeochemical changes occurring in the Southern Ocean. \r\n", "east": -55.0, "geometry": "POINT(-61.5 -59)", "instruments": "IN SITU/LABORATORY INSTRUMENTS \u003e PROFILERS/SOUNDERS \u003e XBT; IN SITU/LABORATORY INSTRUMENTS \u003e PROFILERS/SOUNDERS \u003e ACOUSTIC SOUNDERS \u003e ADCP", "is_usap_dc": true, "keywords": "R/V LMG; Drake Passage; WATER TEMPERATURE; Antarctic Circumpolar Current; Heat Flux", "locations": "Drake Passage", "north": -54.0, "nsf_funding_programs": "Antarctic Ocean and Atmospheric Sciences; Antarctic Ocean and Atmospheric Sciences", "paleo_time": null, "persons": "Chereskin, Teresa; Sprintall, Janet", "platforms": "WATER-BASED PLATFORMS \u003e VESSELS \u003e SURFACE \u003e R/V LMG", "repo": "NCEI", "repositories": "NCEI", "science_programs": null, "south": -64.0, "title": "High Resolution Underway Air-Sea Observations in Drake Passage for Climate Science", "uid": "p0010409", "west": -68.0}, {"awards": "1645087 Catchen, Julian", "bounds_geometry": null, "dataset_titles": "Chromosome-Level Genome Assembly and Circadian Gene Repertoire of the Patagonia Blennie Eleginops maclovinus\u2014The Closest Ancestral Proxy of Antarctic Cryonotothenioids; Evaluating Illumina-, Nanopore-, and PacBio-based genome assembly strategies with the bald notothen, Trematomus borchgrevinki; Genomics of Secondarily Temperate Adaptation in the Only Non-Antarctic Icefish", "datasets": [{"dataset_uid": "200330", "doi": "", "keywords": null, "people": null, "repository": "NCBI ", "science_program": null, "title": "Evaluating Illumina-, Nanopore-, and PacBio-based genome assembly strategies with the bald notothen, Trematomus borchgrevinki", "url": "https://www.ncbi.nlm.nih.gov/bioproject/PRJNA861284"}, {"dataset_uid": "200331", "doi": "10.5061/dryad.ghx3ffbs3", "keywords": null, "people": null, "repository": "Dryad", "science_program": null, "title": "Evaluating Illumina-, Nanopore-, and PacBio-based genome assembly strategies with the bald notothen, Trematomus borchgrevinki", "url": "https://datadryad.org/stash/dataset/doi:10.5061/dryad.ghx3ffbs3"}, {"dataset_uid": "200380", "doi": "", "keywords": null, "people": null, "repository": "NCBI", "science_program": null, "title": "Genomics of Secondarily Temperate Adaptation in the Only Non-Antarctic Icefish", "url": "https://www.ncbi.nlm.nih.gov/bioproject/PRJNA857989"}, {"dataset_uid": "200381", "doi": "", "keywords": null, "people": null, "repository": "NCBI", "science_program": null, "title": "Chromosome-Level Genome Assembly and Circadian Gene Repertoire of the Patagonia Blennie Eleginops maclovinus\u2014The Closest Ancestral Proxy of Antarctic Cryonotothenioids", "url": "https://www.ncbi.nlm.nih.gov/bioproject/PRJNA917608"}], "date_created": "Mon, 10 Oct 2022 00:00:00 GMT", "description": "As plate tectonics pushed Antarctica into a polar position, by ~34 million years ago, the continent and its surrounding Southern Ocean (SO) became geographically and thermally isolated by the Antarctic Circumpolar Current. Terrestrial and marine glaciation followed, resulting in extinctions as well as the survival and radiation of unique flora and fauna. The notothenioid fish survived and arose from a common ancestral stock into tax with 120 species that dominates today\u0027s SO fish fauna. The Notothenioids evolved adaptive traits including novel antifreeze proteins for survival in extreme cold, but also suffered seemingly adverse trait loss including red blood cells in the icefish family, and the ability to mount cellular responses to mitigate heat stress ? otherwise ubiquitous across all life. This project aims to understand how the notothenoid genomes have changed and contributed to their evolution in the cold. The project will sequence, analyze and compare the genomes of two strategic pairs of notothenioid fishes representing both red-blooded and white-blooded species. Each pair will consist of one Antarctic species and one that has readapted to the temperate waters of S. America or New Zealand. The project will also compare the Antarctic species genomes to a genome of the closet non-Antarctic relative representing the temperate notothenioid ancestor. The work aims to uncover the mechanisms that enabled the adaptive evolution of this ecologically vital group of fish in the freezing Southern Ocean, and shed light on their adaptability to a warming world. The finished genomes will be made available to promote and advance Antarctic research and the project will host a symposium of Polar researchers to discuss the cutting edge developments regarding of genomic adaptations in the polar region.\u003cbr/\u003eDespite subzero, icy conditions that are perilous to teleost fish, the fish fauna of the isolated Southern Ocean (SO) surrounding Antarctica is remarkably bountiful. A single teleost group - the notothenioid fishes - dominate the fauna, comprising over 120 species that arose from a common ancestor. When Antarctica became isolated and SO temperatures began to plunge in early Oligocene, the prior temperate fishes became extinct. The ancestor of Antarctic notothenioids overcame forbidding polar conditions and, absent niche competition, it diversified and filled the SO. How did notothenioids adapt to freezing environmental selection pressures and achieve such extraordinary success? And having specialized to life in chronic cold for 30 myr, can they evolve in pace with today\u0027s warming climate to stay viable? Past studies of Antarctic notothenioid evolutionary adaptation have discovered various remarkable traits including the key, life-saving antifreeze proteins. But life specialized to cold also led to paradoxical trait changes such as the loss of the otherwise universal heat shock response, and of the O2-transporting hemoglobin and red blood cells in the icefish family. A few species interestingly regained abilities to live in temperate waters following the escape of their ancestor out of the freezing SO. \u003cbr/\u003eThis proposed project is the first major effort to advance the field from single trait studies to understanding the full spectrum of genomic and genetic responses to climatic and environmental change during notothenioid evolution, and to evaluate their adaptability to continuing climate change. To this end, the project will sequence the genomes of four key species that embody genomic responses to different thermal selection regimes during notothenioids\u0027 evolutionary history, and by comparative analyses of genomic structure, architecture and content, deduce the responding changes. Specifically, the project will (i) obtain whole genome assemblies of the red-blooded T. borchgrevinki and the S. American icefish C. esox; (ii) using the finished genomes from (i) as template, obtain assemblies of the New Zealand notothenioid N. angustata, and the white-blooded icefish C. gunnari, representing a long (11 myr) and recent (1 myr) secondarily temperate evolutionary history respectively. Genes that are under selection in the temperate environment but not in the Antarctic environment can be inferred to be directly necessary for that environment and the reverse is also true for genes under selection in the Antarctic but not in the temperate environment. Further, genes important for survival in temperate waters will show parallel selection between N. angustata and C. esox despite the fact that the two fish left the Antarctic at far separated time points. Finally, gene families that expanded due to strong selection within the cold Antarctic should show a degradation of duplicates in the temperate environment. The project will test these hypotheses using a number of techniques to compare the content and form of genes, the structure of the chromosomes containing those genes, and through the identification of key characters, such as selfish genetic elements, introns, and structural variants.", "east": null, "geometry": null, "instruments": null, "is_usap_dc": true, "keywords": "Genome Assembly; FISH; McMurdo Sound; Icefish; SHIPS; Notothenioid; Puerto Natales, Chile", "locations": "McMurdo Sound; Puerto Natales, Chile", "north": null, "nsf_funding_programs": "Antarctic Organisms and Ecosystems", "paleo_time": null, "persons": "Catchen, Julian; Cheng, Chi-Hing", "platforms": "WATER-BASED PLATFORMS \u003e VESSELS \u003e SURFACE \u003e SHIPS", "repo": "NCBI ", "repositories": "Dryad; NCBI; NCBI ", "science_programs": null, "south": null, "title": "Evolutionary Genomic Responses in Antarctic Notothenioid Fishes", "uid": "p0010384", "west": null}, {"awards": "2135186 Baumberger, Tamara; 2135184 Arrigo, Kevin; 2135185 Resing, Joseph", "bounds_geometry": "POLYGON((155 -61,156.5 -61,158 -61,159.5 -61,161 -61,162.5 -61,164 -61,165.5 -61,167 -61,168.5 -61,170 -61,170 -61.2,170 -61.4,170 -61.6,170 -61.8,170 -62,170 -62.2,170 -62.4,170 -62.6,170 -62.8,170 -63,168.5 -63,167 -63,165.5 -63,164 -63,162.5 -63,161 -63,159.5 -63,158 -63,156.5 -63,155 -63,155 -62.8,155 -62.6,155 -62.4,155 -62.2,155 -62,155 -61.8,155 -61.6,155 -61.4,155 -61.2,155 -61))", "dataset_titles": null, "datasets": null, "date_created": "Fri, 30 Sep 2022 00:00:00 GMT", "description": "Part 1.\r\nPhytoplankton blooms throughout the world support critical marine ecosystems and help remove harmful CO2 from the atmosphere. Traditionally, it has been assumed that phytoplankton blooms in the Southern Ocean are stimulated by iron from either the continental margin or sea-ice. However, recent work demonstrates that hydrothermal vents may be an additional iron source for phytoplankton blooms. This enhancement of phytoplankton productivity by different iron sources supports rich marine ecosystems and leads to the sequestration of C in the deep ocean. Our proposed work will uncover the importance of hydrothermal activity in stimulating a large phytoplankton blooms along the southern boundary of the Antarctic Circumpolar Current just north of the Ross Sea. It will also lead towards a better understanding of the overall impact of hydrothermal activity on the C cycle in the Southern Ocean, which appears to trigger local hotspots of enhanced biological activity which are a potential as a sink for atmospheric CO2. This project will encourage the participation of underrepresented groups in ocean sciences, as well as providing educational opportunities for high school and undergraduate students, through three different programs. Stanford University\u2019s Summer Undergraduate Research in Geoscience and Engineering (SURGE) program provides undergraduates from different US universities and diverse cultural backgrounds the opportunity to spend a summer doing a research project at Stanford. The Stanford Earth Summer Undergraduate Research Program (SESUR) is for Stanford undergraduates who want to learn more about environmental science by performing original research. Finally, Stanford\u2019s School of Earth, Energy, and Environmental Sciences High School Internship Program enables young scientists to serve as mentors, prepares high school students for college, and serves to strengthen the partnership between Stanford and local schools. Students present their results at the Fall AGU meeting as part of the AGU Bright STaRS program. This project will form the basis of at least two Ph.D. dissertations. The Stanford student will participate in Stanford\u2019s Woods Institute Rising Environmental Leaders Program (RELP), a year-round program that helps graduate students hone their leadership and communication skills to maximize the impact of their research. The graduate student will also participate in Stanford\u2019s Grant Writing Academy where they will receive training in developing and articulating research strategies to tackle important scientific questions. \r\n\r\nPart 2.\r\nThis interdisciplinary program combines satellite and ship-based measurements of a large poorly understood phytoplankton bloom (the AAR bloom) in the northwestern Ross Sea sector of the Southern Ocean with a detailed modeling study of the physical processes linking deep dissolved iron (DFe) reservoirs to the surface phytoplankton bloom. Prior to the cruise, we will implement a numerical model (CROCO) for our study region so that we can better understand the circulation, plumes, turbulence, fronts, and eddy field around the AAR bloom and how they transport and mix hydrothermally produced DFe vertically. Post cruise, observations of the vertical distribution of 3He (combined with DMn and DFe), will be used as initial conditions for a passive tracer in the model, and tracer dispersal will be assessed to better quantify the role of the various turbulent processes in upwelling DFe-rich waters to the upper ocean. The satellite-based component of the program will characterize the broader sampling region before, during, and after our cruise. During the cruise, our automated software system at Stanford University will download and process images of sea ice concentration, Chl a concentration, sea surface temperature (SST), and SSH and send them electronically to the ship. Operationally, our goal is to use all available satellite data and preliminary model results to target shipboard sampling both geographically and temporally to optimize sampling of the AAR bloom. We will use available BGC-Argo float data to help characterize the AAR bloom. In collaboration with SOCCOM, we will deploy additional BGC-Argo floats (if available) during our transit through the study area to allow us to better characterize the bloom. The centerpiece of our program will be a 40-day process study cruise in austral summer. The cruise will consist of an initial \u201cradiator\u201d pattern of hydrographic surveys/sections along the AAR followed by CTDs to selected submarine volcanoes. When/if eddies are identified, they will be sampled either during or after the initial surveys. The radiator pattern, or parts thereof, will be repeated 2-3 times. Hydrographic survey stations will include vertical profiles of temperature, salinity, oxygen, oxidation-reduction potential, light scatter, and PAR (400-700 nm). Samples will be collected for trace metals, ligands, 3He, and total suspended matter. Where intense hydrothermal activity is identified, samples for pH and total CO2 will also be collected to characterize the hydrothermal system. Water samples will be collected for characterization of macronutrients, and phytoplankton physiology, abundance, species composition, and size. During transits, we will continuously measure atmospheric conditions, current speed and direction, and surface SST, salinity, pCO2, and fluorescence from the ship\u2019s systems to provide detailed maps of these parameters. The ship will be used as a platform for conducting phytoplankton DFe bioassay experiments at key stations throughout the study region both inside and outside the bloom. We will also perform detailed comparisons of algal taxonomic composition, physiology, and size structure inside and outside the bloom to determine the potential importance of each community on local biogeochemistry.", "east": 170.0, "geometry": "POINT(162.5 -62)", "instruments": null, "is_usap_dc": true, "keywords": "BIOGEOCHEMICAL CYCLES; Antarctica; TRACE ELEMENTS; Hydrothermal Vent; Phytoplankton; Primary Production", "locations": "Antarctica", "north": -61.0, "nsf_funding_programs": "Antarctic Organisms and Ecosystems; Antarctic Integrated System Science; Antarctic Organisms and Ecosystems; Antarctic Organisms and Ecosystems", "paleo_time": null, "persons": "Arrigo, Kevin; Thomas, Leif N; Baumberger, Tamara; Resing, Joseph", "platforms": null, "repositories": null, "science_programs": null, "south": -63.0, "title": "Collaborative Research: Understanding the Massive Phytoplankton Blooms over the Australian-Antarctic Ridge", "uid": "p0010381", "west": 155.0}, {"awards": "2123491 John, Seth; 2123333 Fitzsimmons, Jessica; 2123354 Conway, Timothy", "bounds_geometry": "POLYGON((-135 -66,-131.5 -66,-128 -66,-124.5 -66,-121 -66,-117.5 -66,-114 -66,-110.5 -66,-107 -66,-103.5 -66,-100 -66,-100 -67,-100 -68,-100 -69,-100 -70,-100 -71,-100 -72,-100 -73,-100 -74,-100 -75,-100 -76,-103.5 -76,-107 -76,-110.5 -76,-114 -76,-117.5 -76,-121 -76,-124.5 -76,-128 -76,-131.5 -76,-135 -76,-135 -75,-135 -74,-135 -73,-135 -72,-135 -71,-135 -70,-135 -69,-135 -68,-135 -67,-135 -66))", "dataset_titles": null, "datasets": null, "date_created": "Thu, 08 Sep 2022 00:00:00 GMT", "description": "The goal of the international GEOTRACES program is to understand the distributions of trace chemical elements and their isotopes (TEIs) in the oceans. Many trace metals such as iron are essential for life and thus considered nutrients for phytoplankton growth, with trace metal cycling being especially important for influencing carbon cycling in the iron-limited Southern Ocean, where episodic supply of iron from a range of different external sources is important. The primary goal of this project is to measure the dissolved concentrations, size partitioning, and dissolved isotope signature of Fe on a transect of water-column stations throughout the Amundsen Sea and surrounding region of the Antarctic Margin, as part of the GP17-ANT Expedition. The secondary goal of this project is to analyze the concentrations and size partitioning of the trace metals manganese, zinc, copper, cadmium, nickel, and lead in all water-column samples, measure the isotope ratios of zinc, cadmium, nickel, and copper in a subset of water column samples, and measure the Fe isotopic signature of aerosols, porewaters, and particles. Observations from this project will be incorporated into regional and global biogeochemistry models to assess TEI cycling within the Amundsen Sea and implications for the wider Southern Ocean. This project spans three institutions, four graduate students, undergraduate students, and will provide ultrafiltered samples and data to other PIs as service.\r\n\r\nThe US GEOTRACES GP17 ANT expedition, planned for austral summer 2023/2024 aims to determine the distribution and cycling of trace elements and their isotopes in the Amundsen Sea Sector (100-135\u00b0W) of the Antarctic Margin. The cruise will follow the Amundsen Sea \u2018conveyor belt\u2019 by sampling waters coming from the Antarctic Circumpolar Current onto the continental shelf, including near the Dotson and Pine Island ice shelves, the productive Amundsen Sea Polynya (ASP), and outflowing waters. Episodic addition of dissolved Fe and other TEIs from dust, ice-shelves, melting ice, and sediments drive seasonal primary productivity and carbon export over the Antarctic shelf and offshore into Southern Ocean. Seasonal coastal polynyas such as the highly productive ASP thus act as key levers on global carbon cycling. However, field observations of TEIs in such regions remain scarce, and biogeochemical cycling processes are poorly captured in models of ocean biogeochemistry. The investigators will use their combined analytical toolbox, in collaboration with the diagnostic chemical tracers and regional models of other funded groups to address four main objectives: 1) What is the relative importance of different sources in supplying Fe and other TEIs to the ASP? 2) What is the physiochemical speciation of this Fe, and its potential for transport? 3) How do biological uptake, scavenging and regeneration in the ASP influence TEI distributions, stoichiometry, and nutrient limitation? 4) What is the flux and signature of TEIs transported offshore to the ACC and Southern Ocean?", "east": -100.0, "geometry": "POINT(-117.5 -71)", "instruments": null, "is_usap_dc": true, "keywords": "R/V NBP; Amundsen Sea; TRACE ELEMENTS; BIOGEOCHEMICAL CYCLES", "locations": "Amundsen Sea", "north": -66.0, "nsf_funding_programs": "Chemical Oceanography; Chemical Oceanography; Chemical Oceanography", "paleo_time": null, "persons": "Conway, Timothy; Fitzsimmons, Jessica; John, Seth", "platforms": "WATER-BASED PLATFORMS \u003e VESSELS \u003e SURFACE \u003e R/V NBP", "repositories": null, "science_programs": null, "south": -76.0, "title": "Collaborative Research: US GEOTRACES GP17-ANT: Dissolved concentrations, isotopes, and colloids of the bioactive trace metals", "uid": "p0010374", "west": -135.0}, {"awards": "2148517 Hancock, Cathrine", "bounds_geometry": "POLYGON((-60 -55,-51 -55,-42 -55,-33 -55,-24 -55,-15 -55,-6 -55,3 -55,12 -55,21 -55,30 -55,30 -57,30 -59,30 -61,30 -63,30 -65,30 -67,30 -69,30 -71,30 -73,30 -75,21 -75,12 -75,3 -75,-6 -75,-15 -75,-24 -75,-33 -75,-42 -75,-51 -75,-60 -75,-60 -73,-60 -71,-60 -69,-60 -67,-60 -65,-60 -63,-60 -61,-60 -59,-60 -57,-60 -55))", "dataset_titles": "Trajectories for APEX floats 9223 and 9224 from acoustic tracking using artoa4argo, Mar 2022-Feb 2023; Under ice trajectories for RAFOS enabled profiling floats in the Weddell Gyre", "datasets": [{"dataset_uid": "601652", "doi": "10.15784/601652", "keywords": "Antarctica; ANTXXIV/3; Argo Float; Artoa4argo; GPS Data; RAFOS; US Argo Program; Weddell Sea", "people": "Hancock, Cathrine", "repository": "USAP-DC", "science_program": null, "title": "Under ice trajectories for RAFOS enabled profiling floats in the Weddell Gyre", "url": "https://www.usap-dc.org/view/dataset/601652"}, {"dataset_uid": "601852", "doi": "10.15784/601852", "keywords": "Antarctica; Continental Slope; Cryosphere; Eddy; Float Trajectory; HAFOS; Weddell Sea", "people": "Hancock, Cathrine; Boebel, Olaf", "repository": "USAP-DC", "science_program": null, "title": "Trajectories for APEX floats 9223 and 9224 from acoustic tracking using artoa4argo, Mar 2022-Feb 2023", "url": "https://www.usap-dc.org/view/dataset/601852"}], "date_created": "Fri, 25 Mar 2022 00:00:00 GMT", "description": "The Weddell Gyre is one of the major components of the Southern Ocean circulation system, linking heat and carbon fluxes in the Antarctic Circumpolar Current to the continental margins. Water masses entering the Weddell Gyre are modified as they move in a great circular route around the gyre margin and change through processes involving air-sea-cryosphere interactions as well as through ocean eddies that mix properties across the gyre boundaries. Some of the denser water masses exit the gyre through pathways along the northern boundary, and ultimately ventilate the global deep ocean as Antarctic Bottom Water. While in-situ and satellite observations, as well as computer modeling efforts, provide estimates of the large-scale average flow within the gyre, details of the smaller-scale, or \"mesoscale\" eddy flow remain elusive. The proposed research will quantify mixing due to mesoscale eddies within the Weddell Gyre, as well as the transport of incoming deep water from the northeast, thought to be a result of transient eddies. Since the Weddell Gyre produces source water for about 40% of Antarctic Bottom Water formation, understanding the dynamics in this region helps to identify causes of documented changes in global bottom waters. This in turn, will give insight into how climate change is affecting global oceans, through modification of dense polar waters and Antarctic Bottom Water characteristics.\r\n\r\nThis project aims to track 153 RAFOS-enabled Argo floats in the ice-covered regions of the Weddell Gyre. The resultant tracks along with all available Argo and earlier float data will be used to calculate Eulerian and Lagrangian means and eddy statistics for the Weddell Gyre. The study will link RAFOS tracks with Argo profiles under ice, allowing one to characterize the importance of eddies in water column modification at critical ice-edge boundaries and leads. With RAFOS tracks near the northeastern limit of the gyre, the project will investigate the eddy-driven processes of incoming Circumpolar Deep Water, to understand better the mechanisms and volume fluxes involved. Previous work shows that a large fraction of the mean circulation in the southern and western limits of the gyre, where it contacts the Antarctic continent, occurs in a narrow boundary layer above the slope. The research here will integrate this flow structure into a complete interior and boundary layer mean circulation synthesis. The findings and products from the proposed work will improve the positioning of Argo profiles in the polar regions, which would allow for more accurate climatological maps and derived quantities. Estimates of meso-scale mixing may serve as a foundation for the development of new parameterization schemes employed in climate models, as well as local and global ocean circulation models in polar regions.", "east": 30.0, "geometry": "POINT(-15 -65)", "instruments": null, "is_usap_dc": true, "keywords": "OCEAN CURRENTS; WATER MASSES; BUOYS; USA/NSF; Weddell Sea; AMD; USAP-DC; Amd/Us", "locations": "Weddell Sea", "north": -55.0, "nsf_funding_programs": "Antarctic Ocean and Atmospheric Sciences", "paleo_time": null, "persons": "Hancock, Cathrine; Speer, Kevin", "platforms": "WATER-BASED PLATFORMS \u003e BUOYS \u003e MOORED \u003e BUOYS", "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -75.0, "title": "Weddell Gyre Mean Circulation and Eddy Statistics from Floats", "uid": "p0010310", "west": -60.0}, {"awards": "1916665 Mahon, Andrew; 2225144 Halanych, Kenneth; 1916661 Halanych, Kenneth", "bounds_geometry": "POLYGON((-72 -61,-69.8 -61,-67.6 -61,-65.4 -61,-63.2 -61,-61 -61,-58.8 -61,-56.6 -61,-54.4 -61,-52.2 -61,-50 -61,-50 -61.8,-50 -62.6,-50 -63.4,-50 -64.2,-50 -65,-50 -65.8,-50 -66.6,-50 -67.4,-50 -68.2,-50 -69,-52.2 -69,-54.4 -69,-56.6 -69,-58.8 -69,-61 -69,-63.2 -69,-65.4 -69,-67.6 -69,-69.8 -69,-72 -69,-72 -68.2,-72 -67.4,-72 -66.6,-72 -65.8,-72 -65,-72 -64.2,-72 -63.4,-72 -62.6,-72 -61.8,-72 -61))", "dataset_titles": null, "datasets": null, "date_created": "Wed, 22 Sep 2021 00:00:00 GMT", "description": "Overview: \r\nThe ice cover of Antarctica is changing rapidly, and some reports already suggest we are at, or possibly beyond, the tipping point for the Western Antarctic Ice Sheet collapse. Loss of this ice sheet will have profound effects on marine fauna, including dramatically changing habitat availability for benthic marine species in the Southern Ocean. Formation and collapse of the Western Antarctic Ice Sheet is a cyclical process suggesting that we can learn how fauna respond to ice loss by examining historical climate conditions. Evidence from sediment cores suggests a near complete collapse occurred ~1.1 MYA and modeling suggests a collapse as recent at 125 KYA. During such periods, transantarctic seaways connected the Ross and Weddell Seas. Interestingly, most theories regarding marine invertebrate distributions around the Antarctic focus on dispersal by the Antarctic Circumpolar Current or population bottlenecks and expansions generated by repeated cycles of glaciation and fail to account for transcontinental seaways. Although the impact of previous seaways on genetic structure of present-day populations has been largely ignored, a growing body of data reveal historical connections between Ross and Weddell invertebrate communities, suggesting historical dispersal between these present-day disconnected and distant basins. Future ice shelf collapses will likely reestablish such connections causing redistribution of marine taxa. By exploring alternative hypotheses about the factors that may have shaped patterns of biodiversity in the last couple of million years, our proposed work will aid prediction of possible changes that may, or may not, occur as the Antarctic ice sheets continue to deteriorate.\r\nIntellectual Merit: \r\nThe overarching goal of this research is to understand environmental factors that have shaped patterns of present-day diversity in Antarctic benthic marine invertebrates. Building on our previous work examining circumpolar distributions of multiple marine benthic invertebrate, we are particularly interested in assessing if transantarctic waterways may help explain observed similarities between the Ross and Weddell Seas better than other possible explanations (e.g., dispersal by the Antarctic Circumpolar Current, or expansion from common glacial refugia). To this end, we will employ population genomic approaches using Single Nucleotide Polymorphism (SNP) markers that sample thousands of loci across the genome. Building on our previous phylogeographic studies, we will target 7 Antarctic benthic invertebrate taxa to test alternative hypothesis accounting for population genetic structure. Additionally, the current paradigm is that divergence between closely related, often cryptic, species is the result of genetic drift due to population bottlenecks caused by glaciation. We will directly test this assumption by mapping SNP data on to draft genomes of three of our target taxa to assess the degree of genetic divergence and look for signs of selection. If linkage groups under selection are found, we will examine cellular mechanisms under selection. Thus, our research directly addresses NSF programmatic goals to understand how Antarctic biota evolve and adapt.\r\nBroader Impacts: \r\nOur approach will test several hypotheses that dominate the current understanding of marine biodiversity patterns in the Antarctic providing relevance to several fields of Antarctic science. Also, there are implications for understanding and predicting effects of future ice shelf collapse. The PIs are committed to developing the next generation of researchers and actively engage underrepresented groups at all career stages. We expect to train a minimum of 4 graduate students, a postdoc and several undergraduates on this project. This work will include several specific outreach activities including continuation of our past social media efforts with cruise blogs which were accessed by several thousand unique IP addresses and presentations in K-8 classrooms that reach about 300+ children a year. We also propose to develop 15-20 short YouTube videos on Antarctic genomics as outreach products, we will conduct a photo exhibition, and we will develop two 3-day workshops aimed at students to introduce them to bioinformatics approaches. These works will have formal assessment. \r\nThis proposal requires fieldwork in the Antarctic. \r\n", "east": -50.0, "geometry": "POINT(-61 -65)", "instruments": null, "is_usap_dc": true, "keywords": "Marguerite Bay; USA/NSF; AMD; Weddell Sea; USAP-DC; FIELD SURVEYS; Amd/Us; MARINE ECOSYSTEMS; ANIMALS/INVERTEBRATES", "locations": "Weddell Sea; Marguerite Bay", "north": -61.0, "nsf_funding_programs": "Antarctic Integrated System Science; Antarctic Organisms and Ecosystems; Antarctic Organisms and Ecosystems; Antarctic Organisms and Ecosystems", "paleo_time": null, "persons": "Halanych, Kenneth; Mahon, Andrew", "platforms": "LAND-BASED PLATFORMS \u003e FIELD SITES \u003e FIELD SURVEYS", "repositories": null, "science_programs": null, "south": -69.0, "title": "Collaborative Research: Have transantarctic dispersal corridors impacted Antarctic marine biodiversity?", "uid": "p0010266", "west": -72.0}, {"awards": "2023259 Thompson, Andrew; 2023244 Stewart, Andrew; 2023303 Purkey, Sarah", "bounds_geometry": "POLYGON((-180 -60,-144 -60,-108 -60,-72 -60,-36 -60,0 -60,36 -60,72 -60,108 -60,144 -60,180 -60,180 -63,180 -66,180 -69,180 -72,180 -75,180 -78,180 -81,180 -84,180 -87,180 -90,144 -90,108 -90,72 -90,36 -90,0 -90,-36 -90,-72 -90,-108 -90,-144 -90,-180 -90,-180 -87,-180 -84,-180 -81,-180 -78,-180 -75,-180 -72,-180 -69,-180 -66,-180 -63,-180 -60))", "dataset_titles": "Code for reproducing the ocean-biogeochemical experiments in Sun et al. (2024); Hydrographic data collected from the Bellingshausen and Amundsen seas (NCEI Accession 0210639); Ocean CFC reconstructed data product", "datasets": [{"dataset_uid": "200428", "doi": "", "keywords": null, "people": null, "repository": "NOAA\u0027s National Centers for Environmental Information (NCEI)", "science_program": null, "title": "Hydrographic data collected from the Bellingshausen and Amundsen seas (NCEI Accession 0210639)", "url": "https://data.nodc.noaa.gov/cgi-bin/iso?id=gov.noaa.nodc:0210639"}, {"dataset_uid": "601752", "doi": "10.15784/601752", "keywords": "Antarctica; CFCs; GLODAP; Ocean Model; Ocean Ventilation; Southern Ocean", "people": "Purkey, Sarah; Cimoli, Laura; Gebbie, Jack", "repository": "USAP-DC", "science_program": null, "title": "Ocean CFC reconstructed data product", "url": "https://www.usap-dc.org/view/dataset/601752"}, {"dataset_uid": "200427", "doi": "10.6084/m9.figshare.26787751", "keywords": null, "people": null, "repository": "Figshare (open repository)", "science_program": null, "title": "Code for reproducing the ocean-biogeochemical experiments in Sun et al. (2024)", "url": "https://doi.org/10.6084/m9.figshare.26787751"}], "date_created": "Thu, 01 Jul 2021 00:00:00 GMT", "description": "The formation of dense Antarctic Bottom Water (AABW) and its export northward from the Antarctic continent is one of the key components of the global ocean overturning circulation, and plays a critical role in regulating Earth\u0027s climate on multi-decadal-to-millennial time scales. Recent studies of the global ocean overturning circulation have increasingly emphasized its three-dimensional structure: AABW is produced in a handful of distinct sites around the Antarctic continent, and there is a pronounced asymmetry in the allocation of AABW transports into the Atlantic, Indian and Pacific basins. The connectivity of AABW between the Antarctic continental shelf and the northern basins is mediated by the Antarctic Circumpolar Current (ACC), a circumpolar eastward flow that also serves as the primary route for inter-basin exchange.\r\n\r\nThe mapping from different shelf AABW sources to the northern basins dictates the response of the global MOC to localized variability or shifts in the state of the Antarctic shelf, for example due to major glacier calving events or modified inputs of freshwater from the Antarctic ice sheet. At present this mapping is not well constrained, with conflicting conclusions drawn in previous studies: at one extreme the ACC has been suggested to be a ``conduit\u0027\u0027 that simply allows each variety of AABW to transit directly northward; at the other extreme, it has been suggested that the ACC ``blends\u0027\u0027 all shelf AABW sources together before they reach the northern basins. Such conflicts arise, in part, because little is understood about the physics that determines AABW\u0027s pathways across the ACC.\r\n\r\nTo close this gap in understanding, this collaborative project draws on three complementary analytical tools: process-oriented modeling of AABW export across the ACC, a high-resolution global ocean model, and an observationally-constrained estimate of the global circulation. The PIs will first identify and quantify the pathways of AABW across the ACC by using these tools to propagate passive tracers that identify each of the four major AABW formation sites. They will then use a suite of process model sensitivity experiments to develop a theory for what controls meridional versus inter-basin transport of AABW in the ACC, and transfer this theory to interpret the AABW pathways simulated in the global model. Finally, they will combine the process model, global model and the observationally-constrained circulation product to map the rates at which AABW is transformed into lighter waters, and relate these transformation rates to the diagnosed pathways of AABW across the ACC. This combination of approaches allow the PIs to not only constrain the three-dimensional circulation of AABW from Antarctica to the northern basins, but also provides a mechanistic understanding of the circulation that can be transferred to past or future climates.", "east": 180.0, "geometry": "POINT(0 -89.999)", "instruments": "IN SITU/LABORATORY INSTRUMENTS \u003e DATA ANALYSIS \u003e ENVIRONMENTAL MODELING \u003e COMPUTER", "is_usap_dc": true, "keywords": "AMD; MODELS; USAP-DC; WATER MASSES; Southern Ocean; Amd/Us; OCEAN CURRENTS; COMPUTERS; Antarctic Circumpolar Current; USA/NSF", "locations": "Southern Ocean", "north": -60.0, "nsf_funding_programs": "Antarctic Ocean and Atmospheric Sciences; Antarctic Ocean and Atmospheric Sciences; Antarctic Ocean and Atmospheric Sciences", "paleo_time": null, "persons": "Stewart, Andrew; Thompson, Andrew; Purkey, Sarah", "platforms": "OTHER \u003e MODELS \u003e COMPUTERS; OTHER \u003e MODELS \u003e MODELS", "repo": "NOAA\u0027s National Centers for Environmental Information (NCEI)", "repositories": "Figshare (open repository); NOAA\u0027s National Centers for Environmental Information (NCEI); USAP-DC", "science_programs": null, "south": -90.0, "title": "Collaborative Research: The Antarctic Circumpolar Current: A Conduit or Blender of Antarctic Bottom Waters?", "uid": "p0010220", "west": -180.0}, {"awards": "1341464 Robinson, Rebecca; 1341432 Brzezinski, Mark", "bounds_geometry": "POLYGON((-175 -54,-174 -54,-173 -54,-172 -54,-171 -54,-170 -54,-169 -54,-168 -54,-167 -54,-166 -54,-165 -54,-165 -55.3,-165 -56.6,-165 -57.9,-165 -59.2,-165 -60.5,-165 -61.8,-165 -63.1,-165 -64.4,-165 -65.7,-165 -67,-166 -67,-167 -67,-168 -67,-169 -67,-170 -67,-171 -67,-172 -67,-173 -67,-174 -67,-175 -67,-175 -65.7,-175 -64.4,-175 -63.1,-175 -61.8,-175 -60.5,-175 -59.2,-175 -57.9,-175 -56.6,-175 -55.3,-175 -54))", "dataset_titles": "Diatom assemblage counts from NBP17-02 shipboard carboy experiments; Dissolved nutrient profiles from along 170\u00b0W between 67 and 54\u00b0S; Expedition Data of NBP1702; Particle composition measurements from along 170\u00b0W between 67-54\u00b0S; Particulate silicon and nitrogen concentrations and isotopic composition measurements in McLane pump profiles from 67\u00b0S to 55\u00b0S latitude in the Pacific Sector of the Southern Ocean; Silicon concentration and isotopic composition measurements in pore waters and sediments from 67\u00b0S to 55\u00b0S latitude in the Pacific Sector of the Southern Ocean; Surface Southern Ocean community growouts to evaluate the diatom bound N isotope proxy", "datasets": [{"dataset_uid": "601562", "doi": "10.15784/601562", "keywords": "Antarctica; Biogenic Silica; Chemistry:sediment; Chemistry:Sediment; Lithogenic Silica; Marine Geoscience; NBP1702; Pore Water Biogeochemistry; Sediment; Silicon Cycle; Silicon Stable Isotope; Southern Ocean", "people": "Closset, Ivia; Jones, Janice L.; Brzezinski, Mark", "repository": "USAP-DC", "science_program": null, "title": "Silicon concentration and isotopic composition measurements in pore waters and sediments from 67\u00b0S to 55\u00b0S latitude in the Pacific Sector of the Southern Ocean", "url": "https://www.usap-dc.org/view/dataset/601562"}, {"dataset_uid": "601522", "doi": "10.15784/601522", "keywords": "Antarctica; Nitrogen Isotopes; Oceans; Paleoproxies; Southern Ocean", "people": "Closset, Ivia; Brzezinski, Mark; Robinson, Rebecca; Jones, Colin; Robinson, Rebecca ; Kelly, Roger; Riesselman, Christina", "repository": "USAP-DC", "science_program": null, "title": "Surface Southern Ocean community growouts to evaluate the diatom bound N isotope proxy", "url": "https://www.usap-dc.org/view/dataset/601522"}, {"dataset_uid": "601576", "doi": "10.15784/601576", "keywords": "Antarctica; Biogenic Silica; Chemistry:sediment; Chemistry:Sediment; Diatom; Diatom Bound; Lithogenic Silica; Marine Geoscience; NBP1702; Nitrogen Isotopes; Silicon Cycle; Silicon Stable Isotope; Southern Ocean", "people": "Closset, Ivia; Brzezinski, Mark; Robinson, Rebecca; Jones, Janice L.", "repository": "USAP-DC", "science_program": null, "title": " Particulate silicon and nitrogen concentrations and isotopic composition measurements in McLane pump profiles from 67\u00b0S to 55\u00b0S latitude in the Pacific Sector of the Southern Ocean", "url": "https://www.usap-dc.org/view/dataset/601576"}, {"dataset_uid": "200126", "doi": "10.7284/907211", "keywords": null, "people": null, "repository": "R2R", "science_program": null, "title": "Expedition Data of NBP1702", "url": "https://www.rvdata.us/search/cruise/NBP1702"}, {"dataset_uid": "601276", "doi": "10.15784/601276", "keywords": "Antarctica; Biogenic Silica; Nitrogen Isotopes; Southern Ocean", "people": "Brzezinski, Mark; Robinson, Rebecca", "repository": "USAP-DC", "science_program": null, "title": "Particle composition measurements from along 170\u00b0W between 67-54\u00b0S", "url": "https://www.usap-dc.org/view/dataset/601276"}, {"dataset_uid": "601269", "doi": "10.15784/601269", "keywords": "Antarctica; Chlorophyll; Southern Ocean", "people": "Brzezinski, Mark; Robinson, Rebecca", "repository": "USAP-DC", "science_program": null, "title": "Dissolved nutrient profiles from along 170\u00b0W between 67 and 54\u00b0S", "url": "https://www.usap-dc.org/view/dataset/601269"}, {"dataset_uid": "601523", "doi": "10.15784/601523", "keywords": "Antarctica; Biota; Carboy Growouts; Diatom; Diatom Assemblage Data; NBP1702; Oceans; R/v Nathaniel B. Palmer; Southern Ocean; Southern Ocean Summer", "people": "Riesselman, Christina; Robinson, Rebecca; Jones, Colin; Robinson, Rebecca ", "repository": "USAP-DC", "science_program": null, "title": "Diatom assemblage counts from NBP17-02 shipboard carboy experiments", "url": "https://www.usap-dc.org/view/dataset/601523"}], "date_created": "Wed, 26 Feb 2020 00:00:00 GMT", "description": "The rise in atmospheric carbon dioxide concentrations and associated climate changes make understanding the role of the ocean in large scale carbon cycle a priority. Geologic samples allow exploration of potential mechanisms for carbon dioxide drawdown during glacial periods through the use of geochemical proxies. Nitrogen and silicon isotope signatures from fossil diatoms (microscopic plants) are used to investigate changes in the physical supply and biological demand for nutrients (like nitrogen and silicon and carbon) in the Southern Ocean. The project will evaluate the use the nitrogen and silicon isotope proxies through a series of laboratory experiments and Southern Ocean field sampling. The results will provide quantification of real relationships between nitrogen and silicon isotopes and nutrient usage in the Southern Ocean and allow exploration of the role of other factors, including biological diversity, ice cover, and mixing, in altering the chemical signatures recorded by diatoms. Seafloor sediment samples will be used to evaluate how well the signal created in the water column is recorded by fossil diatoms buried in the seafloor. Improving the nutrient isotope proxies will allow for a more quantitative understanding of the role of polar biology in regulating natural variation in atmospheric carbon dioxide. The project will also result in the training of a graduate student and development of outreach materials targeting a broad popular audience.\r\n\r\nThis project seeks to test the fidelity of the diatom nitrogen and silicon isotope proxies, two commonly used paleoceanographic tools for investigating the role of the Southern Ocean biological pump in regulating atmospheric CO2 concentrations on glacial-interglacial timescales. Existing ground-truthing data, including culture experiments, surface sediment data and downcore reconstructions, all suggest that nutrient utilization is the primary driver of isotopic variation in the Southern Ocean. However, strong contribution of interspecific variation is implied by recent culture results. Moreover, field and laboratory studies present some contradictory results in terms of the relative importance of interspecific variation and of inferred post-depositional alteration of the nutrient isotope signals. Here, a first order test of the N and Si diatom nutrient isotope paleo-proxies, involving water column dissolved and particulate sampling and laboratory culturing of field-isolates, is proposed. Southern Ocean water, biomass, live diatoms and fossil diatom sampling will be conducted to investigate species and assemblage related variability in diatom nitrogen and silicon isotopes and their relationship to surface nutrient fields and early diagenesis. Access to fresh materials produced in an analogous environmental context to the sediments of primary interest is critical for making robust paleoceanographic reconstructions. Field sampling will occur along 175\u00b0W, transecting the Antarctic Circumpolar Current from the subtropics to the marginal ice edge. Collection of water, sinking/suspended particles and multi-core samples from 13 stations and 3 shipboard incubation experiments will be used to test four proposed hypotheses that together evaluate the significance of existing culture results and seek to allow the best use of diatom nutrient isotope proxies in evaluating the biological pump.", "east": -165.0, "geometry": "POINT(-170 -60.5)", "instruments": null, "is_usap_dc": true, "keywords": "Southern Ocean; AMD; NITROGEN ISOTOPES; R/V NBP; NSF/USA; NUTRIENTS; USAP-DC; Amd/Us", "locations": "Southern Ocean", "north": -54.0, "nsf_funding_programs": "Antarctic Earth Sciences; Antarctic Earth Sciences", "paleo_time": null, "persons": "Robinson, Rebecca; Brzezinski, Mark", "platforms": "WATER-BASED PLATFORMS \u003e VESSELS \u003e SURFACE \u003e R/V NBP", "repo": "USAP-DC", "repositories": "R2R; USAP-DC", "science_programs": null, "south": -67.0, "title": "Collaborative Proposal: A Field and Laboratory Examination of the Diatom N and Si Isotope Proxies: Implications for Assessing the Southern Ocean Biological Pump", "uid": "p0010083", "west": -175.0}, {"awards": "1246111 Dalziel, Ian", "bounds_geometry": "POLYGON((-44 -53,-42.9 -53,-41.8 -53,-40.7 -53,-39.6 -53,-38.5 -53,-37.4 -53,-36.3 -53,-35.2 -53,-34.1 -53,-33 -53,-33 -53.4,-33 -53.8,-33 -54.2,-33 -54.6,-33 -55,-33 -55.4,-33 -55.8,-33 -56.2,-33 -56.6,-33 -57,-34.1 -57,-35.2 -57,-36.3 -57,-37.4 -57,-38.5 -57,-39.6 -57,-40.7 -57,-41.8 -57,-42.9 -57,-44 -57,-44 -56.6,-44 -56.2,-44 -55.8,-44 -55.4,-44 -55,-44 -54.6,-44 -54.2,-44 -53.8,-44 -53.4,-44 -53))", "dataset_titles": "BAS Geological Collection: Central Scotia Sea (full data link not provided); Nathaniel B Palmer NBP 1408; South Georgia: SOG1, SOG2, SOG3", "datasets": [{"dataset_uid": "200107", "doi": "", "keywords": null, "people": null, "repository": "British Antarctic Survey", "science_program": null, "title": "BAS Geological Collection: Central Scotia Sea (full data link not provided)", "url": "https://www.bas.ac.uk/data/our-data/collections/geological-collections/"}, {"dataset_uid": "200106", "doi": "", "keywords": null, "people": null, "repository": "MGDS", "science_program": null, "title": "Nathaniel B Palmer NBP 1408", "url": "http://www.marine-geo.org/tools/search/entry.php?id=NBP1408"}, {"dataset_uid": "200105", "doi": "", "keywords": null, "people": null, "repository": "UNAVCO", "science_program": null, "title": "South Georgia: SOG1, SOG2, SOG3", "url": "https://www.unavco.org/data/gps-gnss/gps-gnss.html"}], "date_created": "Tue, 28 Jan 2020 00:00:00 GMT", "description": "Intellectual Merit: \u003cbr/\u003eOpening of Drake Passage and the West Scotia Sea south of Tierra del Fuego broke the final continental barrier to onset of a complete Antarctic Circumpolar Current (ACC). Initiation of the ACC has been associated in time with a major, abrupt, drop in global temperatures and the rapid expansion of the Antarctic ice sheets at 33-34 Ma. Events leading to the formation of the Drake Passage gateway are poorly known. Understanding the tectonic evolution of the floor of the Central Scotia Sea (CSS) and the North Scotia Ridge is a key to this understanding. Previous work has demonstrated that superimposed constructs formed a volcanic arc that likely blocked direct eastward flow from the Pacific to the Atlantic through the opening Drake Passage gateway as the active South Sandwich arc does today. The PIs propose a cruise to test, develop and refine, with further targeted mapping and dredging, their theory of CSS tectonics and the influence it had on the onset and development of the ACC. In addition they propose an installation of GPS receiver to test their paleogeographic reconstructions and determine whether South Georgia is moving as part of the South American plate. \u003cbr/\u003e\u003cbr/\u003eBroader impacts: \u003cbr/\u003eA graduate student will be involved in all stages of the research. Undergraduate students will also be involved as watch-standers. A community college teacher will participate in the cruise. The PIs will have a website on which there will be images of the actual ocean floor dredging in operation. The teacher will participate with web and outreach support through PolarTREC. Results of the cruise are of broad interest to paleoceanographers, paleoclimate modelers and paleobiogeographers.A network of four continuous Global Navigational Satellite Systems (GNSS) receivers was installed on the bedrock of South Georgia in the Southern Ocean in 2013 and 2014. An additional receiver on a concrete foundation provides a tie to a tide gauge, part of the United Kingdom South Atlantic Tide Gauge Network. The GNSS receivers have already provided data suggesting that the South Georgia microcontinent (SGM) is moving independent of both the South American plate to the north and the Scotia plate to the south. The data also demonstrate that the SGM is being uplifted. ", "east": -33.0, "geometry": "POINT(-38.5 -55)", "instruments": "NOT APPLICABLE \u003e NOT APPLICABLE \u003e NOT APPLICABLE", "is_usap_dc": true, "keywords": "Scotia Sea; PLATE BOUNDARIES; TECTONIC PROCESSES; NOT APPLICABLE; COASTAL ELEVATION; Southern Ocean; USAP-DC", "locations": "Scotia Sea; Southern Ocean", "north": -53.0, "nsf_funding_programs": "Antarctic Glaciology; Antarctic Earth Sciences", "paleo_time": null, "persons": "Dalziel, Ian W.; Lawver, Lawrence; Krissek, Lawrence", "platforms": "OTHER \u003e NOT APPLICABLE \u003e NOT APPLICABLE", "repo": "British Antarctic Survey", "repositories": "British Antarctic Survey; MGDS; UNAVCO", "science_programs": null, "south": -57.0, "title": "Collaborative Research: Role of the Central Scotia Sea Floor and North Scotia Ridge in the Onset and Development of the Antarctic Circumpolar Current", "uid": "p0010078", "west": -44.0}, {"awards": "1341496 Girton, James", "bounds_geometry": "POLYGON((-142 -66,-135.3 -66,-128.6 -66,-121.9 -66,-115.2 -66,-108.5 -66,-101.8 -66,-95.1 -66,-88.4 -66,-81.7 -66,-75 -66,-75 -66.8,-75 -67.6,-75 -68.4,-75 -69.2,-75 -70,-75 -70.8,-75 -71.6,-75 -72.4,-75 -73.2,-75 -74,-81.7 -74,-88.4 -74,-95.1 -74,-101.8 -74,-108.5 -74,-115.2 -74,-121.9 -74,-128.6 -74,-135.3 -74,-142 -74,-142 -73.2,-142 -72.4,-142 -71.6,-142 -70.8,-142 -70,-142 -69.2,-142 -68.4,-142 -67.6,-142 -66.8,-142 -66))", "dataset_titles": "Bottom Photographs from the Antarctic Peninsula acquired during R/V Laurence M. Gould expedition LMG1703; Expedition Data; Expedition data of NBP1701", "datasets": [{"dataset_uid": "002661", "doi": null, "keywords": null, "people": null, "repository": "R2R", "science_program": null, "title": "Expedition data of NBP1701", "url": "https://www.rvdata.us/search/cruise/NBP1701"}, {"dataset_uid": "601302", "doi": null, "keywords": "Antarctica; Antarctic Peninsula; Benthic Images; Benthos; Biota; LMG1708; Oceans; Photo; Photo/video; Photo/Video; R/v Laurence M. Gould; Ship; Yoyo Camera", "people": "Girton, James", "repository": "USAP-DC", "science_program": null, "title": "Bottom Photographs from the Antarctic Peninsula acquired during R/V Laurence M. Gould expedition LMG1703", "url": "https://www.usap-dc.org/view/dataset/601302"}, {"dataset_uid": "001369", "doi": "", "keywords": null, "people": null, "repository": "R2R", "science_program": null, "title": "Expedition Data", "url": "https://www.rvdata.us/search/cruise/NBP1701"}], "date_created": "Tue, 10 Dec 2019 00:00:00 GMT", "description": "Current oceanographic interest in the interaction of relatively warm water of the Southern Ocean Circumpolar Deep Water (CDW) as it moves southward to the frigid waters of the Antarctic continental shelves is based on the potential importance of heat transport from the global ocean to the base of continental ice shelves. This is needed to understand the longer term mass balance of the continent, the stability of the vast Antarctic ice sheets and the rate at which sea-level will rise in a warming world. Improved observational knowledge of the mechanisms of how warming CDW moves across the Antarctic Circumpolar Current (ACC) is needed. Understanding this dynamical transport, believed to take place through the eddy flux of time-varying mesoscale circulation features, will improve coupled ocean-atmospheric climate models. The development of the next generation of coupled ocean-ice-climate models help us understand future changes in atmospheric heat fluxes, glacial and sea-ice balance, and changes in the Antarctic ecosystems. A recurring obstacle to our understanding is the lack of data in this distant region. In this project, a total of 10 subsurface profiling EM-APEX floats adapted to operate under sea ice were launched in 12 missions (and 2 recoveries) from 4 cruises of opportunity to the Amundsen Sea sector of the Antarctic continental margin during Austral summer. The floats were launched south of the Polar Front and measured shear, turbulence, temperature, and salinity to 2000m depth for 1-2 year missions while drifting with the CDW layer between profiles.", "east": -75.0, "geometry": "POINT(-108.5 -70)", "instruments": "IN SITU/LABORATORY INSTRUMENTS \u003e PROFILERS/SOUNDERS \u003e CTD; IN SITU/LABORATORY INSTRUMENTS \u003e CHEMICAL METERS/ANALYZERS \u003e FLUOROMETERS; IN SITU/LABORATORY INSTRUMENTS \u003e MAGNETIC/MOTION SENSORS \u003e GRAVIMETERS \u003e GRAVIMETERS; IN SITU/LABORATORY INSTRUMENTS \u003e RECORDERS/LOGGERS \u003e AWS; EARTH REMOTE SENSING INSTRUMENTS \u003e PASSIVE REMOTE SENSING \u003e POSITIONING/NAVIGATION \u003e GPS \u003e GPS; EARTH REMOTE SENSING INSTRUMENTS \u003e ACTIVE REMOTE SENSING \u003e PROFILERS/SOUNDERS \u003e ACOUSTIC SOUNDERS \u003e ECHO SOUNDERS; IN SITU/LABORATORY INSTRUMENTS \u003e PROFILERS/SOUNDERS \u003e ACOUSTIC SOUNDERS \u003e MBES; IN SITU/LABORATORY INSTRUMENTS \u003e PROFILERS/SOUNDERS \u003e THERMOSALINOGRAPHS; IN SITU/LABORATORY INSTRUMENTS \u003e PHOTON/OPTICAL DETECTORS \u003e CAMERAS \u003e CAMERA", "is_usap_dc": true, "keywords": "OCEAN TEMPERATURE; R/V NBP; USAP-DC; ICE DEPTH/THICKNESS; HEAT FLUX; OCEAN CURRENTS; SALINITY/DENSITY; LMG1703; Bellingshausen Sea; Yoyo Camera; WATER MASSES; R/V LMG; NBP1701", "locations": "Bellingshausen Sea", "north": -66.0, "nsf_funding_programs": "Antarctic Ocean and Atmospheric Sciences", "paleo_time": null, "persons": "Girton, James; Rynearson, Tatiana", "platforms": "WATER-BASED PLATFORMS \u003e VESSELS \u003e SURFACE \u003e R/V LMG; WATER-BASED PLATFORMS \u003e VESSELS \u003e SURFACE \u003e R/V NBP", "repo": "R2R", "repositories": "R2R; USAP-DC", "science_programs": null, "south": -74.0, "title": "Collaborative Research: Pathways of Circumpolar Deep Water to West Antarctica from Profiling Float and Satellite Measurements", "uid": "p0010074", "west": -142.0}, {"awards": "0636493 Chereskin, Teresa; 0635437 Donohue, Kathleen", "bounds_geometry": "POLYGON((-65.09 -54.96,-64.618 -54.96,-64.146 -54.96,-63.674 -54.96,-63.202 -54.96,-62.73 -54.96,-62.258 -54.96,-61.786 -54.96,-61.314 -54.96,-60.842 -54.96,-60.37 -54.96,-60.37 -55.661,-60.37 -56.362,-60.37 -57.063,-60.37 -57.764,-60.37 -58.465,-60.37 -59.166,-60.37 -59.867,-60.37 -60.568,-60.37 -61.269,-60.37 -61.97,-60.842 -61.97,-61.314 -61.97,-61.786 -61.97,-62.258 -61.97,-62.73 -61.97,-63.202 -61.97,-63.674 -61.97,-64.146 -61.97,-64.618 -61.97,-65.09 -61.97,-65.09 -61.269,-65.09 -60.568,-65.09 -59.867,-65.09 -59.166,-65.09 -58.465,-65.09 -57.764,-65.09 -57.063,-65.09 -56.362,-65.09 -55.661,-65.09 -54.96))", "dataset_titles": "Expedition Data", "datasets": [{"dataset_uid": "001463", "doi": "", "keywords": null, "people": null, "repository": "R2R", "science_program": null, "title": "Expedition Data", "url": "https://www.rvdata.us/search/cruise/NBP1004"}, {"dataset_uid": "001522", "doi": "", "keywords": null, "people": null, "repository": "R2R", "science_program": null, "title": "Expedition Data", "url": "https://www.rvdata.us/search/cruise/NBP1107"}, {"dataset_uid": "001521", "doi": "", "keywords": null, "people": null, "repository": "R2R", "science_program": null, "title": "Expedition Data", "url": "https://www.rvdata.us/search/cruise/NBP0710"}, {"dataset_uid": "001490", "doi": "", "keywords": null, "people": null, "repository": "R2R", "science_program": null, "title": "Expedition Data", "url": "https://www.rvdata.us/search/cruise/NBP0812"}, {"dataset_uid": "001476", "doi": "", "keywords": null, "people": null, "repository": "R2R", "science_program": null, "title": "Expedition Data", "url": "https://www.rvdata.us/search/cruise/NBP0908"}], "date_created": "Tue, 12 Aug 2014 00:00:00 GMT", "description": "The proposed work is a multi-year study of the transport of water through Drake Passage by the Antarctic Circumpolar Current (ACC). Drake Passage acts as a chokepoint that is not only well suited geographically for measuring the time-varying transport, but observations and computer models suggest that dynamical balances which control the transport are particularly effective here. An array of Current Meters and Pressure-recording Inverted Echo Sounders (CPIES) will be set out for a period of 4 years to quantify the transport and dynamics of the Antarctic Circumpolar Current. Data will be collected annually by acoustic telemetry, leaving the instruments undisturbed until recovered at the end of the project. \u003cbr/\u003e\u003cbr/\u003eThe Southern Ocean is believed to be especially sensitive to climate change, responding to winds that have increased over the past thirty years, and warming significantly more than the global ocean over the past fifty years. The proposed observations will resolve the seasonal and interannual variability of the total ACC transport, as well as its vertical and lateral structure. Although not submitted specifically to the International Polar Year (IPY) Program Solicitation, the proposed project contributes to the IPY goal of understanding environmental change in polar regions and represents a pulse of activity in the IPY time frame that will extend the legacy of the IPY. The data and findings will be reported to publicly accessible archives and submitted for publication in the scientific literature. It is a scientific collaboration between the University of California, San Diego, and the University of Rhode Island.", "east": -60.37, "geometry": "POINT(-62.73 -58.465)", "instruments": "EARTH REMOTE SENSING INSTRUMENTS \u003e PASSIVE REMOTE SENSING \u003e POSITIONING/NAVIGATION \u003e GPS \u003e GPS; IN SITU/LABORATORY INSTRUMENTS \u003e PROFILERS/SOUNDERS \u003e CTD; IN SITU/LABORATORY INSTRUMENTS \u003e MAGNETIC/MOTION SENSORS \u003e GRAVIMETERS \u003e GRAVIMETERS; IN SITU/LABORATORY INSTRUMENTS \u003e PRESSURE/HEIGHT METERS \u003e PRESSURE SENSORS; IN SITU/LABORATORY INSTRUMENTS \u003e SAMPLERS \u003e BOTTLES/FLASKS/JARS \u003e WATER BOTTLES; IN SITU/LABORATORY INSTRUMENTS \u003e PROFILERS/SOUNDERS \u003e ACOUSTIC SOUNDERS \u003e ADCP; IN SITU/LABORATORY INSTRUMENTS \u003e PROFILERS/SOUNDERS \u003e ACOUSTIC SOUNDERS \u003e MSBS", "is_usap_dc": false, "keywords": "R/V NBP", "locations": null, "north": -54.96, "nsf_funding_programs": "Antarctic Ocean and Atmospheric Sciences; Antarctic Ocean and Atmospheric Sciences", "paleo_time": null, "persons": "Chereskin, Teresa; Donohue, Kathleen; Watts, D.; Tracey, Karen; Kennelly, Maureen", "platforms": "WATER-BASED PLATFORMS \u003e VESSELS \u003e SURFACE \u003e R/V NBP", "repo": "R2R", "repositories": "R2R", "science_programs": null, "south": -61.97, "title": "Collaborative Research: Dynamics and Transport of the Antarctic Circumpolar Current in Drake Passage", "uid": "p0000543", "west": -65.09}, {"awards": "1232962 Ledwell, James", "bounds_geometry": null, "dataset_titles": "Expedition data of NBP1310A", "datasets": [{"dataset_uid": "002658", "doi": null, "keywords": null, "people": null, "repository": "R2R", "science_program": null, "title": "Expedition data of NBP1310A", "url": "https://www.rvdata.us/search/cruise/NBP1310A"}], "date_created": "Fri, 07 Feb 2014 00:00:00 GMT", "description": "Intellectual Merit: The Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean (DIMES) is a study of ocean mixing in the Antarctic Circumpolar Current (ACC) which runs west to east all around the continent of Antarctica, south of the other continents. This current system is somewhat of a barrier to transport of heat, carbon dioxide and other important ocean constituents between the far south and the rest of the ocean, and mixing processes play an important role in those transports. DIMES is a multi-investigator cooperative project, led by physical oceanographers in the U.S. and in the U.K. A passive tracer and an array of sub-surface floats were deployed early in 2009 more than 2000 km west of Drake Passage on a surface of constant density about 1500 m deep between the Sub Antarctic Front and the Polar Front of the ACC. In early 2010 a U.S. led research cruise sampled the tracer, turbulence levels, and the velocity and density profiles that govern the generation of that turbulence, and additional U.K. led research cruises in 2011 and 2012 continue this sampling as the tracer has made its way through Drake Passage, into the Scotia Sea, and over the North Scotia Ridge, a track of more than 3000 km. The initial results show that diapycnal, i.e., vertical, mixing west of Drake Passage where the bottom is relatively smooth is no larger than in most other regions of the open ocean. In contrast, there are strong velocity shears and intense turbulence levels over the rough topography in Drake Passage and diapycnal diffusivity of the tracer more than 10 times larger in Drake Passage and to the east than west of Drake Passage.\u003cbr/\u003e\u003cbr/\u003eThe DIMES field program continues with the U.S. team collecting new velocity and turbulence data in the Scotia Sea. It is anticipated that the tracer will continue passing through the Scotia Sea until at least early 2014. The U.K. partners have scheduled sampling of the tracer on cruises at the North Scotia Ridge and in the eastern and central Scotia Sea in early 2013 and early 2014. The current project will continue the time series of the tracer at Drake Passage on two more U.S. led cruises, in late 2012 and late 2013. Trajectories through the Scotia Sea estimated from the tracer observations, from neutrally buoyant floats, and from numerical models will be used to accurately estimate mixing rates of the tracer and to locate where the mixing is concentrated. During the 2013 cruise the velocity and turbulence fields along high-resolution transects along the ACC and across the ridges of Drake Passage will be measured to see how far downstream of the ridges the mixing is enhanced, and to test the hypothesis that mixing is enhanced by breaking lee waves generated by flow over the rough topography.\u003cbr/\u003e\u003cbr/\u003eBroader Impacts: DIMES (see web site at http://dimes.ucsd.edu) involves many graduate students and post-doctoral researchers. Two graduate students, who would become expert in ocean turbulence and the processes generating it, will continue be trained on this project. The work in DIMES is ultimately motivated by the need to understand the overturning circulation of the global ocean. This circulation governs the transport and storage of heat and carbon dioxide within the huge oceanic reservoir, and thus plays a major role in regulating the earth?s climate. Understanding the circulation and how it changes in reaction to external forces is necessary to the understanding of past climate change and of how climate might change in the future, and is therefore of great importance to human well-being. The data collected and analyzed by the DIMES project will be assembled and made publicly available at the end of the project.\u003cbr/\u003e\u003cbr/\u003eThe DIMES project is a process experiment sponsored by the U.S. CLIVAR (Climate variability and predictability) program.", "east": null, "geometry": null, "instruments": "IN SITU/LABORATORY INSTRUMENTS \u003e PROFILERS/SOUNDERS \u003e CTD; IN SITU/LABORATORY INSTRUMENTS \u003e CHEMICAL METERS/ANALYZERS \u003e FLUOROMETERS; IN SITU/LABORATORY INSTRUMENTS \u003e MAGNETIC/MOTION SENSORS \u003e GRAVIMETERS \u003e GRAVIMETERS; IN SITU/LABORATORY INSTRUMENTS \u003e RECORDERS/LOGGERS \u003e AWS; EARTH REMOTE SENSING INSTRUMENTS \u003e PASSIVE REMOTE SENSING \u003e POSITIONING/NAVIGATION \u003e GPS \u003e GPS; EARTH REMOTE SENSING INSTRUMENTS \u003e ACTIVE REMOTE SENSING \u003e PROFILERS/SOUNDERS \u003e ACOUSTIC SOUNDERS \u003e ECHO SOUNDERS; IN SITU/LABORATORY INSTRUMENTS \u003e PROFILERS/SOUNDERS \u003e ACOUSTIC SOUNDERS \u003e MBES; IN SITU/LABORATORY INSTRUMENTS \u003e PROFILERS/SOUNDERS \u003e THERMOSALINOGRAPHS", "is_usap_dc": false, "keywords": "R/V NBP", "locations": null, "north": null, "nsf_funding_programs": null, "paleo_time": null, "persons": "Ledwell, James", "platforms": "WATER-BASED PLATFORMS \u003e VESSELS \u003e SURFACE \u003e R/V NBP", "repo": "R2R", "repositories": "R2R", "science_programs": null, "south": null, "title": "Studies of Turbulence and Mixing in the Antarctic Circumpolar Current, a Continuation of DIMES", "uid": "p0000846", "west": null}, {"awards": "1019838 Wendt, Dean", "bounds_geometry": null, "dataset_titles": "Real-Time Characterization of Adelie Penguin Foraging Environment Using an Autonomous Underwater Vehicle", "datasets": [{"dataset_uid": "600120", "doi": "10.15784/600120", "keywords": "Biota; Oceans; Southern Ocean", "people": "Wendt, Dean; Moline, Mark", "repository": "USAP-DC", "science_program": null, "title": "Real-Time Characterization of Adelie Penguin Foraging Environment Using an Autonomous Underwater Vehicle", "url": "https://www.usap-dc.org/view/dataset/600120"}], "date_created": "Mon, 30 Dec 2013 00:00:00 GMT", "description": "Abstract \u003cbr/\u003e\u003cbr/\u003eThis award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). \u003cbr/\u003e\u003cbr/\u003eThe Antarctic Peninsula is among the most rapidly warming regions on earth. Increased heat from the Antarctic Circumpolar Current has elevated the temperature of the 300 m of shelf water below the permanent pycnocline by 0.7 degrees C. This trend has displaced the once dominant cold, dry continental Antarctic climate, and is causing multi-level responses in the marine ecosystem. One striking example of the ecosystem response to warming has been the local declines in ice-dependent Ad\u00c3\u00a9lie penguins. The changes in these apex predators are thought to be driven by alterations in phytoplankton and zooplankton community composition, and the foraging limitations and diet differences between these species. One of the most elusive questions facing researchers interested in the foraging ecology of the Ad\u00c3\u00a9lie penguin, namely, what are the biophysical properties that characterize the three dimensional foraging space of this top predator? The research will combine the real-time site and diving information from the Ad\u00c3\u00a9lie penguin satellite tags with the full characterization of the oceanography and the penguins prey field using an autonomous underwater vehicle (AUV). While some of these changes have been documented over large spatial scales of the WAP, it is now thought that the causal mechanisms that favor of one life history strategy over another may actually operate over much smaller scales than previously thought, specifically on the scale of local breeding sites and over-wintering areas. Characterization of prey fields on these local scales has yet to be done and one that the AUV is ideally suited. The results will have a direct tie to the climate induced changes that are occurring in the West Antarctic Peninsula. This study will also highlight a new approach to linking an autonomous platform to bird behavior that could be expanded to include the other two species of penguins and examine the seasonal differences in their foraging behavior and prey selection. From a vehicle perspective, this effort will inform the AUV user community of new sensor suites and/or data processing approaches that are required to better evaluate foraging habitat. The project also will help transition AUV platforms into routine investigative tools for this region, which is chronically under sampled and will remain difficult to access", "east": null, "geometry": null, "instruments": null, "is_usap_dc": true, "keywords": "USA/NSF; Amd/Us; USAP-DC; AMD; FIELD INVESTIGATION", "locations": null, "north": null, "nsf_funding_programs": "Antarctic Organisms and Ecosystems", "paleo_time": null, "persons": "Wendt, Dean; Moline, Mark", "platforms": "LAND-BASED PLATFORMS \u003e FIELD SITES \u003e FIELD INVESTIGATION", "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": null, "title": "Real-Time Characterization of Adelie Penguin Foraging Environment Using an Autonomous Underwater Vehicle", "uid": "p0000662", "west": null}, {"awards": "0948338 Mitchell, B. Gregory; 0948357 Measures, Christopher", "bounds_geometry": "POLYGON((-63 -60,-62 -60,-61 -60,-60 -60,-59 -60,-58 -60,-57 -60,-56 -60,-55 -60,-54 -60,-53 -60,-53 -60.45,-53 -60.9,-53 -61.35,-53 -61.8,-53 -62.25,-53 -62.7,-53 -63.15,-53 -63.6,-53 -64.05,-53 -64.5,-54 -64.5,-55 -64.5,-56 -64.5,-57 -64.5,-58 -64.5,-59 -64.5,-60 -64.5,-61 -64.5,-62 -64.5,-63 -64.5,-63 -64.05,-63 -63.6,-63 -63.15,-63 -62.7,-63 -62.25,-63 -61.8,-63 -61.35,-63 -60.9,-63 -60.45,-63 -60))", "dataset_titles": "Project: Blue Water Zone; Trace Metal data 2006 (ID3801); Trace Metals - 2004", "datasets": [{"dataset_uid": "000174", "doi": "", "keywords": null, "people": null, "repository": "BCO-DMO", "science_program": null, "title": "Trace Metal data 2006 (ID3801)", "url": "https://www.bco-dmo.org/dataset/3801"}, {"dataset_uid": "000173", "doi": "", "keywords": null, "people": null, "repository": "BCO-DMO", "science_program": null, "title": "Project: Blue Water Zone", "url": "http://www.bco-dmo.org/project/2145"}, {"dataset_uid": "000218", "doi": "", "keywords": null, "people": null, "repository": "BCO-DMO", "science_program": null, "title": "Trace Metals - 2004", "url": "https://www.bco-dmo.org/dataset/3800"}], "date_created": "Fri, 22 Nov 2013 00:00:00 GMT", "description": "The ocean plays a critical role in sequestering CO2 by exporting fixed carbon to the deep ocean through the biological pump. There is a pressing need to understand the systematics of carbon export in the Southern Ocean in the context of global warming because of the sensitivity of this region to climate change, already manifested as significant temperature increases. Numerous studies have indicated that Fe supply is a primary control on phytoplankton biomass and productivity in the Southern Ocean. The results from previous cruises in Feb-Mar 2004 and Jul-Aug 2006 have revealed the major natural Fe fertilization from Fe-rich shelf waters to the Fe-limited high nutrient low chlorophyll (HNLC) Antarctic Circumpolar Current Surface Water (ASW) in the southern Drake Passage, producing a series of phytoplankton blooms. Remaining questions include: How is natural Fe transported to the euphotic zone through small-meso-large scale horizontal-vertical transport and mixing in different HNLC ACC areas? How does plankton community structure evolve in response to a natural Fe addition, how does Fe speciation respond to biogeochemical processes, and how is Fe recycled to determine the longevity of phytoplankton blooms? How does the export of POC evolve as a function of upwelling-mixing, Fe addition-recycling and bacteria-plankton structure? This synthesis proposal will address these fundamental questions using a unique dataset combining multiyear physical, Fe and biogeochemical data collected between 2004 and 2006 from 2 NSF-funded Fe fertilization experiment cruises and 3 Antarctic Marine Living Resource (AMLR) cruises in the southern Drake Passage and southwestern Scotia Sea through collaboration with scientists in the AMLR program and US Southern Ocean GLOBEC projects. All investigators involved in this study are engaged in graduate and undergraduate instruction, and mentoring of postdoctoral researchers. Each P.I. will incorporate key elements of the proposed syntheses in our lectures, problem sets and group projects. The project includes support to convene a 4-5 day international workshop on natural Fe fertilization at Woods Hole Oceanographic Institution. The workshop will include scientists from United Kingdom, France and Germany who have conducted natural Fe fertilization experiments, and Korea and China who are planning to conduct natural Fe fertilization experiments. The participation of graduate students and postdoctoral scholars will be especially encouraged. The results will be published in a Deep-Sea Research II special issue.", "east": -53.0, "geometry": "POINT(-58 -62.25)", "instruments": null, "is_usap_dc": true, "keywords": "Not provided", "locations": null, "north": -60.0, "nsf_funding_programs": "Antarctic Organisms and Ecosystems; Antarctic Organisms and Ecosystems", "paleo_time": null, "persons": "Mitchell, B.; Azam, Farooq; Barbeau, Katherine; Gille, Sarah; Holm-Hansen, Osmund; Measures, Christopher; Selph, Karen", "platforms": "Not provided", "repo": "BCO-DMO", "repositories": "BCO-DMO", "science_programs": null, "south": -64.5, "title": "Collaborative Research: Modeling and synthesis study of a natural iron fertilization site in the Southern Drake Passage", "uid": "p0000071", "west": -63.0}, {"awards": "9910164 Scheltema, Rudolf", "bounds_geometry": "POLYGON((-70.557 -52.351,-68.9316 -52.351,-67.3062 -52.351,-65.6808 -52.351,-64.0554 -52.351,-62.43 -52.351,-60.8046 -52.351,-59.1792 -52.351,-57.5538 -52.351,-55.9284 -52.351,-54.303 -52.351,-54.303 -53.60557,-54.303 -54.86014,-54.303 -56.11471,-54.303 -57.36928,-54.303 -58.62385,-54.303 -59.87842,-54.303 -61.13299,-54.303 -62.38756,-54.303 -63.64213,-54.303 -64.8967,-55.9284 -64.8967,-57.5538 -64.8967,-59.1792 -64.8967,-60.8046 -64.8967,-62.43 -64.8967,-64.0554 -64.8967,-65.6808 -64.8967,-67.3062 -64.8967,-68.9316 -64.8967,-70.557 -64.8967,-70.557 -63.64213,-70.557 -62.38756,-70.557 -61.13299,-70.557 -59.87842,-70.557 -58.62385,-70.557 -57.36928,-70.557 -56.11471,-70.557 -54.86014,-70.557 -53.60557,-70.557 -52.351))", "dataset_titles": "Expedition Data", "datasets": [{"dataset_uid": "001846", "doi": "", "keywords": null, "people": null, "repository": "R2R", "science_program": null, "title": "Expedition Data", "url": "https://www.rvdata.us/search/cruise/LMG0109"}], "date_created": "Tue, 04 May 2010 00:00:00 GMT", "description": "Because of the extreme isolation of Antarctica since the early Oligocene one can expect to encounter a unique invertebrate fauna with a high degree of endemism. Yet, some benthic taxa include from 20 to \u003e50 percent non-endemic species. To account for such species it has been proposed that an intermittent reciprocal exchange must occur between the antiboreal populations of South America and the Antarctic continent. One possible means by which the geographical distribution can be maintained and genetic exchange may be accomplished is by the passive dispersal of planktonic larvae. To show that such dispersal is actually accomplished it must be demonstrated that (1) larvae of sublittoral species actually are found within the Drake passage and that such larvae belong to species that occur both in the antiboreal South American and Antarctic faunas and (2) that a hydrographic mechanism exists that can explain how the passive transport of larvae may occur between the two continents. The proposed research will address these two requirements by making transects of plankton samples across the Drake passage and by examining the possibility of cross frontal exchange of larvae at the subantarctic and polar fronts of the Antarctic circumpolar current as well as the possible transport of larvae in mesoscale rings. The outcome may suggest species that in the future may profitably be examined using molecular techniques, comparing individuals from bottom populations of South America and Antarctica. The study necessarily must be of a very preliminary nature since the occurrence of planktonic larvae of sublittoral benthic species in the Drake Passage has never before been examined.", "east": -54.303, "geometry": "POINT(-62.43 -58.62385)", "instruments": null, "is_usap_dc": false, "keywords": "R/V LMG", "locations": null, "north": -52.351, "nsf_funding_programs": "Antarctic Organisms and Ecosystems", "paleo_time": null, "persons": "Scheltema, Rudolf; Veit, Richard", "platforms": "WATER-BASED PLATFORMS \u003e VESSELS \u003e SURFACE \u003e R/V LMG", "repo": "R2R", "repositories": "R2R", "science_programs": null, "south": -64.8967, "title": "SGER: Dispersal of Planktonic Invertebrate Larvae and the Biogeography of the Antarctic Benthos", "uid": "p0000602", "west": -70.557}, {"awards": "0444134 Mitchell, B. Gregory", "bounds_geometry": null, "dataset_titles": "Expedition data of NBP0606", "datasets": [{"dataset_uid": "002646", "doi": null, "keywords": null, "people": null, "repository": "R2R", "science_program": null, "title": "Expedition data of NBP0606", "url": "https://www.rvdata.us/search/cruise/NBP0606"}], "date_created": "Tue, 04 May 2010 00:00:00 GMT", "description": "The Shackleton Fracture Zone (SFZ) in Drake Passage of the Southern Ocean defines a boundary between low and high phytoplankton waters. Low chlorophyll water flowing through the southern Drake Passage emerges as high chlorophyll water to the east, and recent evidence indicates that the Southern Antarctic Circumpolar Current Front (SACCF) is steered south of the SFZ onto the Antarctic Peninsula shelf where mixing between the water types occurs. The mixed water is then advected off-shelf with elevated iron and phytoplankton biomass. The SFZ is therefore an ideal natural laboratory to improve the understanding of plankton community responses to natural iron fertilization, and how these processes influence export of organic carbon to the ocean interior. The bathymetry of the region is hypothesized to influence mesoscale circulation and transport of iron, leading to the observed patterns in phytoplankton biomass. The position of the Antarctic Circumpolar Current (ACC) is further hypothesized to influence the magnitude of the flow of ACC water onto the peninsula shelf, mediating the amount of iron transported into the Scotia Sea. To address these hypotheses, a research cruise will be conducted near the SFZ and to the east in the southern Scotia Sea. A mesoscale station grid for vertical profiles, water sampling, and bottle incubation enrichment experiments will complement rapid surface surveys of chemical, plankton, and hydrographic properties. Distributions of manganese, aluminum and radium isotopes will be determined to trace iron sources and estimate mixing rates. Phytoplankton and bacterial physiological states (including responses to iron enrichment) and the structure of the plankton communities will be studied. The primary goal is to better understand how plankton productivity, community structure and export production in the Southern Ocean are affected by the coupling between bathymetry, mesoscale circulation, and distributions of limiting nutrients. The proposed work represents an interdisciplinary approach to address the fundamental physical, chemical and biological processes that contribute to the abrupt transition in chl-a which occurs near the SFZ. Given recent indications that the Southern Ocean is warming, it is important to advance the understanding of conditions that regulate the present ecosystem structure in order to predict the effects of climate variability. This project will promote training and learning across a broad spectrum of groups. Funds are included to support postdocs, graduate students, and undergraduates. In addition, this project will contribute to the development of content for the Polar Science Station website, which has been a resource since 2001 for instructors and students in adult education, home schooling, tribal schools, corrections education, family literacy programs, and the general public.", "east": null, "geometry": null, "instruments": "IN SITU/LABORATORY INSTRUMENTS \u003e PROFILERS/SOUNDERS \u003e ACOUSTIC SOUNDERS \u003e MSBS", "is_usap_dc": false, "keywords": "R/V NBP", "locations": null, "north": null, "nsf_funding_programs": "Antarctic Organisms and Ecosystems", "paleo_time": null, "persons": "Mitchell, B.", "platforms": "WATER-BASED PLATFORMS \u003e VESSELS \u003e SURFACE \u003e R/V NBP", "repo": "R2R", "repositories": "R2R", "science_programs": null, "south": null, "title": "Collaborative Research: Plankton Community Structure and Iron Distribution in the Southern Drake Passage and Scotia Sea", "uid": "p0000837", "west": null}, {"awards": "0338248 Takahashi, Taro", "bounds_geometry": "POLYGON((-68.0051 -52.7573,-67.35191 -52.7573,-66.69872 -52.7573,-66.04553 -52.7573,-65.39234 -52.7573,-64.73915 -52.7573,-64.08596 -52.7573,-63.43277 -52.7573,-62.77958 -52.7573,-62.12639 -52.7573,-61.4732 -52.7573,-61.4732 -53.96927,-61.4732 -55.18124,-61.4732 -56.39321,-61.4732 -57.60518,-61.4732 -58.81715,-61.4732 -60.02912,-61.4732 -61.24109,-61.4732 -62.45306,-61.4732 -63.66503,-61.4732 -64.877,-62.12639 -64.877,-62.77958 -64.877,-63.43277 -64.877,-64.08596 -64.877,-64.73915 -64.877,-65.39234 -64.877,-66.04553 -64.877,-66.69872 -64.877,-67.35191 -64.877,-68.0051 -64.877,-68.0051 -63.66503,-68.0051 -62.45306,-68.0051 -61.24109,-68.0051 -60.02912,-68.0051 -58.81715,-68.0051 -57.60518,-68.0051 -56.39321,-68.0051 -55.18124,-68.0051 -53.96927,-68.0051 -52.7573))", "dataset_titles": "Expedition Data", "datasets": [{"dataset_uid": "001572", "doi": "", "keywords": null, "people": null, "repository": "R2R", "science_program": null, "title": "Expedition Data", "url": "https://www.rvdata.us/search/cruise/LMG0603"}], "date_created": "Tue, 04 May 2010 00:00:00 GMT", "description": "This proposal is for the continuation and expansion of an underway program on the R/V Laurence M. Gould to measure dissolved carbon dioxide gas (pCO2) along with occasional total carbon dioxide (TCO2) in surface waters on transects of Drake Passage. The added observations include dissolved oxygen, as well as nutrient and carbon-13. The proposed work is similar to the underway measurement program made aboard R/V Nathaniel B. Palmer, and complements similar surface temperature and current data.\u003cbr/\u003eThe Southern Ocean is an important component of the global carbon budget. Low surface temperatures with consequently low vertical stability, ice formation, and high winds produce a very active environment for the exchange of gaseous carbon dioxide between the atmospheric and oceanic reservoirs. The Drake Passage is the narrowest point through which the Antarctic Circumpolar Current and its associated fronts must pass, and is the most efficient location for the measurement of latitudinal gradients of gas exchange. The generated time series will contribute towards two scientific goals: the quantification of the spatial and temporal variability and trends of surface carbon dioxide, oxygen, nutrients and C-13, and an understanding of the dominant processes that contribute to the observed variability.", "east": -61.4732, "geometry": "POINT(-64.73915 -58.81715)", "instruments": "IN SITU/LABORATORY INSTRUMENTS \u003e PROFILERS/SOUNDERS \u003e CTD; EARTH REMOTE SENSING INSTRUMENTS \u003e PASSIVE REMOTE SENSING \u003e POSITIONING/NAVIGATION \u003e GPS \u003e GPS; IN SITU/LABORATORY INSTRUMENTS \u003e PROFILERS/SOUNDERS \u003e ACOUSTIC SOUNDERS \u003e ADCP", "is_usap_dc": false, "keywords": "R/V LMG", "locations": null, "north": -52.7573, "nsf_funding_programs": "Antarctic Ocean and Atmospheric Sciences", "paleo_time": null, "persons": "Takahashi, Taro", "platforms": "WATER-BASED PLATFORMS \u003e VESSELS \u003e SURFACE \u003e R/V LMG", "repo": "R2R", "repositories": "R2R", "science_programs": null, "south": -64.877, "title": "Collaborative Research: Processes Driving Spatial and Temporal Variability of Surface pCO2 in the Drake Passage", "uid": "p0000572", "west": -68.0051}, {"awards": "0230284 Yuan, Xiaojun", "bounds_geometry": "POLYGON((-40 -35,-24 -35,-8 -35,8 -35,24 -35,40 -35,56 -35,72 -35,88 -35,104 -35,120 -35,120 -38.5,120 -42,120 -45.5,120 -49,120 -52.5,120 -56,120 -59.5,120 -63,120 -66.5,120 -70,104 -70,88 -70,72 -70,56 -70,40 -70,24 -70,8 -70,-8 -70,-24 -70,-40 -70,-40 -66.5,-40 -63,-40 -59.5,-40 -56,-40 -52.5,-40 -49,-40 -45.5,-40 -42,-40 -38.5,-40 -35))", "dataset_titles": "CTD station data WOD Accession# 0053045.", "datasets": [{"dataset_uid": "000200", "doi": "", "keywords": null, "people": null, "repository": "NCEI", "science_program": null, "title": "CTD station data WOD Accession# 0053045.", "url": "http://www.nodc.noaa.gov/"}], "date_created": "Sat, 20 Feb 2010 00:00:00 GMT", "description": "This work is the continuation of a joint project with the Polar Research Institute of China to make measurements of the structure of the upper ocean in the northern Weddell Sea along the route taken by the PRI\u0027s antarctic supply vessel, R/V Xue Long. The observations, obtained from expendable instruments, complement existing hydrographic observations along various transects through the northwestern Weddell Sea region and data from moored current meter arrays in the Weddell-Scotia confluence zone. This effort builds upon a successful series of expendable bathythermographs and conductivity-temperature-depth probes obtained by the science party on board the R/V Xue Long for the past four years.\u003cbr/\u003eThe west-to-east transit of the Weddell Sea by the ship makes it possible to obtain a series of ocean soundings that are otherwise unobtainable. The information is particularly important because strong correlative links between the upper ocean temperature and salinity, the sea ice edge, and extra-polar climate features have been established. It has been shown that the Indian Ocean sector is an anomalous region with respect to connections between antarctic and lower latitude climatic features and indices. Here the Antarctic Circumpolar Current makes its closest approach to the continent and the Antarctic Circumpolar Wave is least well expressed in the existing data. The necessary instrumentation, both software and hardware, has been installed in the ship and an excellent working relationship with Chinese antarctic scientists has been developed.", "east": 120.0, "geometry": "POINT(40 -52.5)", "instruments": null, "is_usap_dc": true, "keywords": "Not provided", "locations": null, "north": -35.0, "nsf_funding_programs": "Antarctic Ocean and Atmospheric Sciences", "paleo_time": null, "persons": "Yuan, Xiaojun; Martinson, Douglas", "platforms": "Not provided", "repo": "NCEI", "repositories": "NCEI", "science_programs": null, "south": -70.0, "title": "U.S./Chinese Ship of Opportunity Sampling Program Phase II", "uid": "p0000558", "west": -40.0}, {"awards": "0439759 Ballard, Grant", "bounds_geometry": "POLYGON((-180 -60,-177.5 -60,-175 -60,-172.5 -60,-170 -60,-167.5 -60,-165 -60,-162.5 -60,-160 -60,-157.5 -60,-155 -60,-155 -61.76,-155 -63.52,-155 -65.28,-155 -67.04,-155 -68.8,-155 -70.56,-155 -72.32,-155 -74.08,-155 -75.84,-155 -77.6,-157.5 -77.6,-160 -77.6,-162.5 -77.6,-165 -77.6,-167.5 -77.6,-170 -77.6,-172.5 -77.6,-175 -77.6,-177.5 -77.6,180 -77.6,178.5 -77.6,177 -77.6,175.5 -77.6,174 -77.6,172.5 -77.6,171 -77.6,169.5 -77.6,168 -77.6,166.5 -77.6,165 -77.6,165 -75.84,165 -74.08,165 -72.32,165 -70.56,165 -68.8,165 -67.04,165 -65.28,165 -63.52,165 -61.76,165 -60,166.5 -60,168 -60,169.5 -60,171 -60,172.5 -60,174 -60,175.5 -60,177 -60,178.5 -60,-180 -60))", "dataset_titles": "Access to data; Adelie penguin banding data 1994-2021 from the California Avian Data Center hosted by Point Reyes Bird Observatory Conservation Science; Adelie penguin resighting data 1997-2021 from the California Avian Data Center hosted by Point Reyes Bird Observatory Conservation Science", "datasets": [{"dataset_uid": "601443", "doi": "10.15784/601443", "keywords": "Adelie Penguin; Antarctica; Biota; Demography; Penguin; Ross Sea; Seabirds", "people": "Ballard, Grant", "repository": "USAP-DC", "science_program": null, "title": "Adelie penguin banding data 1994-2021 from the California Avian Data Center hosted by Point Reyes Bird Observatory Conservation Science", "url": "https://www.usap-dc.org/view/dataset/601443"}, {"dataset_uid": "601444", "doi": "10.15784/601444", "keywords": "Adelie Penguin; Antarctica; Biota; Demography; Mark-Recapture; Monitoring; Penguin; Ross Island", "people": "Ballard, Grant", "repository": "USAP-DC", "science_program": null, "title": "Adelie penguin resighting data 1997-2021 from the California Avian Data Center hosted by Point Reyes Bird Observatory Conservation Science", "url": "https://www.usap-dc.org/view/dataset/601444"}, {"dataset_uid": "001368", "doi": "", "keywords": null, "people": null, "repository": "CADC", "science_program": null, "title": "Access to data", "url": "http://data.prbo.org/apps/penguinscience/AllData/mammals"}], "date_created": "Tue, 19 May 2009 00:00:00 GMT", "description": "This project is an international collaborative investigation of geographic structuring, founding of new colonies, and population change of Adelie penguins (Pygoscelis adelia) nesting on Ross and Beaufort islands, Antarctica. The long-term changes occurring at these colonies are representative of changes throughout the Ross Sea, where 30% of all Adelie penguins reside, and are in some way related to changing climate. The recent grounding of two very large icebergs against Ross and Beaufort islands, with associated increased variability in sea-ice extent, has provided an unparalleled natural experiment affecting wild, interannual swings in colony productivity, foraging effort, philopatry and recruitment. Results of this natural experiment can provide insights into the demography and geographic population structuring of this species, having relevance Antarctic-wide in understanding its future responses to climate change as well as interpreting its amazingly well known Holocene history. This ongoing study will continue to consider the relative importance of resources that constrain or enhance colony growth (nesting habitat, access to food); the aspects of natural history that are affected by exploitative or interference competition among neighboring colonies (breeding success, foraging effort); climatic factors that influence the latter, especially sea ice patterns; and behavioral mechanisms that influence colony growth as a function of initial size and location (emigration, immigration). An increased effort will focus on understanding factors that affect over-winter survival. The hypothesis is that the age structure of Cape Crozier has changed over the past thirty years and no longer reflects the smaller colonies nearby. Based on recent analyses, it appears that the Ross Island penguins winter in a narrow band of sea ice north of the Antarctic Circle (where daylight persists) and south of the southern boundary of the Antarctic Circumpolar Current (where food abounds). More extensive winter ice takes the penguins north of that boundary where they incur higher mortality. Thus, where a penguin winters may be due to the timing of its post-breeding departure (which differs among colonies), which affects where it first encounters sea ice on which to molt and where it will be transported by the growing ice field. Foraging effort and interference competition for food suggested as factors driving the geographic structuring of colonies. The research includes a census of known-age penguins, studies of foraging effort and overlap among colonies; and identification of the location of molting and wintering areas. Information will be related to sea-ice conditions as quantified by satellite images. Demographic and foraging-effort models will be used to synthesize results. The iceberg natural experiment is an unparalleled opportunity to investigate the demographics of a polar seabird and its response to climate change. The marked, interannual variability in apparent philopatry, with concrete data being collected on its causes, is a condition rarely encountered among studies of vertebrates. Broader impacts include collaborating with New Zealand and Italian researchers, involving high school teachers and students in the fieldwork and continuing a website to highlight results to both scientists and the general public.", "east": -155.0, "geometry": "POINT(-175 -68.8)", "instruments": null, "is_usap_dc": false, "keywords": "Not provided", "locations": null, "north": -60.0, "nsf_funding_programs": "Antarctic Organisms and Ecosystems", "paleo_time": null, "persons": "Ballard, Grant", "platforms": "Not provided", "repo": "USAP-DC", "repositories": "CADC; USAP-DC", "science_programs": null, "south": -77.6, "title": "COLLABORATIVE: Geographic Structure of Adelie Penguin Colonies - Demography of Population Change", "uid": "p0000068", "west": 165.0}, {"awards": "0230268 Anderson, Robert", "bounds_geometry": "POLYGON((-180 -50,-169 -50,-158 -50,-147 -50,-136 -50,-125 -50,-114 -50,-103 -50,-92 -50,-81 -50,-70 -50,-70 -51.5,-70 -53,-70 -54.5,-70 -56,-70 -57.5,-70 -59,-70 -60.5,-70 -62,-70 -63.5,-70 -65,-81 -65,-92 -65,-103 -65,-114 -65,-125 -65,-136 -65,-147 -65,-158 -65,-169 -65,180 -65,177 -65,174 -65,171 -65,168 -65,165 -65,162 -65,159 -65,156 -65,153 -65,150 -65,150 -63.5,150 -62,150 -60.5,150 -59,150 -57.5,150 -56,150 -54.5,150 -53,150 -51.5,150 -50,153 -50,156 -50,159 -50,162 -50,165 -50,168 -50,171 -50,174 -50,177 -50,-180 -50))", "dataset_titles": "Southern Ocean Deglacial Opal, Radionuclide, and Diatom Upwelling Data", "datasets": [{"dataset_uid": "000199", "doi": "", "keywords": null, "people": null, "repository": "NCEI", "science_program": null, "title": "Southern Ocean Deglacial Opal, Radionuclide, and Diatom Upwelling Data", "url": "https://www.ncdc.noaa.gov/paleo/study/8439"}], "date_created": "Mon, 12 Jan 2009 00:00:00 GMT", "description": "This award, provided by the Antarctic Geology and Geophysics Program of the Office of Polar Programs, supports a project to investigate the \"Silicic Acid Leakage Hypothesis\" as it relates to global carbon dioxide fluctuations during glacial-interglacial cycles.\u003cbr/\u003e\u003cbr/\u003eIntellectual Merit\u003cbr/\u003eThis project will evaluate the burial rate of biogenic opal in the Pacific sector of the Southern Ocean, both during the Last Glacial Maximum (LGM) and during the Holocene, as a critical test of the \"Silicic Acid Leakage Hypothesis\". \u003cbr/\u003e\u003cbr/\u003eThe \"Silicic Acid Leakage Hypothesis\" has been proposed recently to explain the glacial reduction in the carbon dioxide content of the atmosphere that has been reconstructed from Antarctic ice cores. Vast amounts of dissolved Si (silicic acid) are supplied to surface waters of the Southern Ocean by wind-driven upwelling of deep waters. Today, that dissolved Si is consumed almost quantitatively by diatoms who form skeletal structures composed of biogenic opal (a mineral form of silicon). According to the \"Silicic Acid Leakage Hypothesis\", environmental conditions in the Southern Ocean during glacial periods were unfavorable for diatom growth, leading to reduced (compared to interglacials) efficiency of dissolved Si utilization. Dissolved Si that was not consumed biologically in the glacial Southern ocean was then exported to the tropics in waters that sink in winter to depths of a few hundred meters along the northern fringes of the Antarctic Circumpolar Current, and return some decades later to the sunlit surface in tropical regions of wind-driven upwelling. \u003cbr/\u003e\u003cbr/\u003eAn increase in the amount of dissolved Si that \"leaks\" out of the Southern Ocean and later upwells at low latitudes could shift the global average composition of phytoplankton toward a greater abundance of diatoms and fewer CaCO3-secreting taxa (especially coccolithophorids). Consequences of such a taxonomic shift in the ocean\u0027s phytoplankton assemblage include:\u003cbr/\u003e a) an increase in the global average organic carbon/calcium carbonate ratio of particulate biogenic material sinking into the deep sea;\u003cbr/\u003e b) a reduction in the preservation and burial of calcium carbonate in marine sediments;\u003cbr/\u003e c) an increase in ocean alkalinity as a consequence of the first two changes mentioned above, and;\u003cbr/\u003e d) a lowering of atmospheric CO2 concentrations in response to increased alkalinity of ocean waters. \u003cbr/\u003e\u003cbr/\u003eA complete assessment of the Silicic acid leakage hypothesis will require an evaluation of: (1) Si utilization efficiencies using newly-developed stable isotopic techniques; (2) opal burial rates in low-latitude upwelling regions; and (3) opal burial rates in the Southern Ocean. This project addresses the last of these topics. \u003cbr/\u003e\u003cbr/\u003ePrevious work has shown that there was little change in opal burial rate between the LGM and the Holocene in the Atlantic and Indian sectors of the Southern Ocean. Preliminary results (summarized in this proposal) suggest that the Pacific may have been different, however, in that opal burial rates in the Pacific sector seem to have been lower during the LGM than during the Holocene, allowing for the possibility of \"Si leakage\" from this region. However, available results are too sparse to make any quantitative conclusions at this time. For that reason, we propose to make a comprehensive evaluation of opal burial rates in the Pacific sector of the Southern Ocean. \u003cbr/\u003e\u003cbr/\u003eSignificance and Broader Impacts\u003cbr/\u003eDetermining the mechanism(s) by which the ocean has regulated climate-related changes in the CO2 content of the atmosphere has been the focus of a substantial effort by paleoceanographers over the past two decades. The Silicic Acid Leakage Hypothesis is a viable new candidate mechanism that warrants further exploration and testing. Completion of the proposed work will contribute significantly to that effort. \u003cbr/\u003e\u003cbr/\u003eDuring the course of this work, several undergraduates will be exposed to paleoclimate research through their involvement in this project. Burckle and Anderson are both dedicated to the education and training of young scientists, and to the recruitment of women and under-represented minorities. To illustrate, two summer students (undergraduates) worked in Burckle\u0027s lab during the summer of 2002. One was a woman and the other (male) was a member of an under-represented minority. Anderson and Burckle will continue with similar recruitment efforts during the course of the proposed study. A minority student who has expressed an interest in working on this research during the summer of 2003 has already been identified.", "east": -70.0, "geometry": "POINT(-140 -57.5)", "instruments": null, "is_usap_dc": true, "keywords": "Not provided", "locations": null, "north": -50.0, "nsf_funding_programs": "Antarctic Earth Sciences", "paleo_time": null, "persons": "Anderson, Robert; Burckle, Lloyd", "platforms": "Not provided", "repo": "NCEI", "repositories": "NCEI", "science_programs": null, "south": -65.0, "title": "Opal Burial in the Pacific Sector of the Southern Ocean: A Test of the \"Silicic Acid Leakage Hypothesis.\"", "uid": "p0000457", "west": 150.0}, {"awards": "0088054 Goldstein, Steven", "bounds_geometry": "POLYGON((-180 -39.57,-144 -39.57,-108 -39.57,-72 -39.57,-36 -39.57,0 -39.57,36 -39.57,72 -39.57,108 -39.57,144 -39.57,180 -39.57,180 -42.967,180 -46.364,180 -49.761,180 -53.158,180 -56.555,180 -59.952,180 -63.349,180 -66.746,180 -70.143,180 -73.54,144 -73.54,108 -73.54,72 -73.54,36 -73.54,0 -73.54,-36 -73.54,-72 -73.54,-108 -73.54,-144 -73.54,-180 -73.54,-180 -70.143,-180 -66.746,-180 -63.349,-180 -59.952,-180 -56.555,-180 -53.158,-180 -49.761,-180 -46.364,-180 -42.967,-180 -39.57))", "dataset_titles": null, "datasets": null, "date_created": "Tue, 26 Apr 2005 00:00:00 GMT", "description": "This award, provided by the Antarctic Geology and Geophysics Program of the Office of Polar Programs, supports a project to investigate the sediment core from the Southern Ocean for paleoenvironmental research. The polar regions are susceptible to the largest changes in climate and are among the least accessible places on Earth. Current concern about the instability of the West Antarctic Ice Sheet has heightened awareness of the vulnerability of polar regions. This proposal seeks to gain a basic understanding of the isotopic characteristics of terrigenous sediment sources derived from Antarctica in the Holocene and Last Glacial Maximum, and their dispersal into the Southern Ocean. Terrigenous clastic sediments are brought to the ocean from continental sources via rivers, ice and wind, and distributed within the ocean by surface and deep currents. At present there are virtually no isotopic data on circumpolar detritus, save a few strontium (Sr) isotopic ratios in the Atlantic sector. This project will fill part of this gap. From the large range in geological ages of crustal provinces of Antarctica, we would predict that there are large isotopic differences in detritus around the continent. The main objectives are to (1) characterize the strontium-neodymium-lead-argon (Sr-Nd-Pb-Ar) isotope compositions of sediment sources derived from Antarctica, (2) to identify the composition and source ages of major ice rafted detritus (IRD) contributions by analyzing individual grains of hornblende and feldspar in conjunction with bulk isotopic analysis, and (3) track sediment dispersal into the Antarctic Circumpolar Current (ACC) during the Holocene and Last Glacial Maximum.\u003cbr/\u003e\u003cbr/\u003eBecause of the paucity of circumpolar data, this research necessarily has a large exploratory component. Consequently, it will provide a basic database for future studies. Nevertheless there are important hypothesis-driven questions that will be addressed in this primary pass. Can lessons learned in North Atlantic IRD studies be applied toward understanding the history of Antarctic ice sheets? Can the large geological variability around the Antarctic margin be treated as a series of natural tracer injections into the ACC, and thus characterize its trajectory, speed, and interaction with other current systems today and in the past? The proposed study is motivated by an exciting set of results from the South Atlantic, showing that detrital Sr isotope ratios are a sensitive current tracer in that region. This research should serve a basic need across many Earth Science disciplines if the use of long-lived radiogenic isotopes (Sr-Nd-Pb-Ar) as tracers of marine sediment sources is successful in elucidating processes related to changing climatic conditions. The results of this study will fill a basic gap in our knowledge of an important region of the Earth. At the same time, it will provide an essential basis for attempting reconstruction of the ACC during the LGM, as well as for future studies of Antarctic geology, ice sheet history, and the Southern Ocean circulation.", "east": 180.0, "geometry": "POINT(0 -89.999)", "instruments": null, "is_usap_dc": false, "keywords": "Not provided", "locations": null, "north": -39.57, "nsf_funding_programs": "Antarctic Earth Sciences", "paleo_time": null, "persons": "Roy, Martin; Hemming, Sidney R.; Goldstein, Steven L.; Van De Flierdt, Christina-Maria", "platforms": "Not provided", "repositories": null, "science_programs": null, "south": -73.54, "title": "Establishing the Pattern of Holocene-LGM Changes in Sediment Contributions from Antarctica to the Southern Ocean", "uid": "p0000724", "west": -180.0}]

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