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.
Rapid changes in the extent and thickness of sea ice during the austral spring subject microorganisms within or attached to the ice to large fluctuations in temperature, salinity, light and nutrients. This project aims to identify cellular responses in sea-ice algae to increasing temperature and decreasing salinity during the spring melt along the western Antarctic Peninsula and to determine how associated changes at the cellular level can potentially affect dynamic, biologically driven processes. Understanding how sea-ice algae cope with, and are adapted to, their environment will not only help predict how polar ecosystems may change as the extent and thickness of sea ice change, but will also provide a better understanding of the widespread success of photosynthetic life on Earth. The scientific context and resulting advances from the research will be communicated to the general public through outreach activities that includes work with Science Communication Fellows and the popular Polar Science Weekend at the Pacific Science Center in Seattle, Washington. The project will provide student training to college students as well as provide for educational experiences for K-12 school children. <br/><br/><br/>There is currently a poor understanding of feedback relationships that exist between the rapidly changing environment in the western Antarctic Peninsula region and sea-ice algal production. The large shifts in temperature and salinity that algae experience during the spring melt affect critical cellular processes, including rates of enzyme-catalyzed reactions involved in photosynthesis and respiration, and the production of stress-protective compounds. These changes in cellular processes are poorly constrained but can be large and may have impacts on local ecosystem productivity and biogeochemical cycles. In particular, this study will focus on the thermal sensitivity of enzymes and the cycling of compatible solutes and exopolymers used for halo- and cryo-protection, and how they influence primary production and the biogeochemical cycling of carbon and nitrogen. Approaches will include field sampling during spring melt, incubation experiments of natural sea-ice communities under variable temperature and salinity conditions, and controlled manipulation of sea-ice algal species in laboratory culture. Employment of a range of techniques, from fast repetition rate fluorometry and gross and net photosynthetic measurements to metabolomics and enzyme kinetics, will tease apart the mechanistic effects of temperature and salinity on cell metabolism and primary production with the goal of quantifying how these changes will impact biogeochemical processes along the western Antarctic Peninsula.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
The Ross Ice Shelf is the largest existing ice shelf in Antarctica, and is currently stabilizing significant portions of the land ice atop the Antarctic continent. An ice shelf begins where the land ice goes afloat on the ocean, and as such, the Ross Ice Shelf interacts with the ocean and seafloor below, and the land ice behind. Currently, the Ross Ice Shelf slows down, or buttresses, the fast flowing ice streams of the West Antarctic Ice Sheet (WAIS), a marine-based ice sheet, which if melted, would raise global sea level by 3-4 meters. The Ross Ice Shelf average ice thickness is approximately 350 meters, and it covers approximately 487,000 square kilometers, an area slightly larger than the state of California. The Ross Ice Shelf has disappeared during prior interglacial periods, suggesting in the future it may disappear again. Understanding the dynamics, stability and future of the West Antarctic Ice Sheet therefore requires in-depth knowledge of the Ross Ice Shelf. The ROSETTA-ICE project brings together scientists from 4 US institutions and from the Institute of Geological and Nuclear Sciences Limited, known as GNS Science, New Zealand. The ROSETTA-ICE data on the ice shelf, the water beneath the ice shelf, and the underlying rocks, will allow better predictions of how the Ross Ice Shelf will respond to changing climate, and therefore how the WAIS will behave in the future. The interdisciplinary ROSETTA-ICE team will train undergraduate and high school students in cutting edge research techniques, and will also work to educate the public via a series of vignettes integrating ROSETTA-ICE science with the scientific and human history of Antarctic research.<br/><br/>The ROSETTA-ICE survey will acquire gravity and magnetics data to determine the water depth beneath the ice shelf. Radar, LIDAR and imagery systems will be used to map the Ross Ice Shelf thickness and fine structure, crevasses, channels, debris, surface accumulation and distribution of marine ice. The high resolution aerogeophysical data over the Ross Ice Shelf region in Antarctica will be acquired using the IcePod sensor suite mounted externally on an LC-130 aircraft operating from McMurdo Station, Antarctica. Field activities will include ~36 flights on LC-130 aircraft over two field seasons in Antarctica. The IcePod instrument suite leverages the unique experience of the New York Air National Guard operating in Antarctica for NSF scientific research as well as infrastructure and logistics. The project will answer questions about the stability of the Ross Ice Shelf in future climate, and the geotectonic evolution of the Ross Ice Shelf Region, a key component of the West Antarctic Rift system. The comprehensive benchmark data sets acquired will enable broad, interdisciplinary analyses and modeling, which will also be performed as part of the project. ROSETTA-ICE will illuminate Ross ice sheet-ice shelf-ocean dynamics as the system nears a critical juncture but still is intact. Through interacting with an online data visualization tool, and comparing the ROSETTA-ICE data and results from earlier studies, we will engage students and young investigators, equipping them with new capabilities for the study of critical earth systems that influence global climate.
The one place on Earth consistently showing increases in sea ice area, duration, and concentration is the Ross Sea in Antarctica. Satellite imagery shows about half of the Ross Sea increases are associated with changes in the austral fall, when the new sea ice is forming. The most pronounced changes are also located near polynyas, which are areas of open ocean surrounded by sea ice. To understand the processes driving the sea ice increase, and to determine if the increase in sea ice area is also accompanied by a change in ice thickness, this project will conduct an oceanographic cruise to the polynyas of the Ross Sea in April and May, 2017, which is the austral fall. The team will deploy state of the art research tools including unmanned airborne systems (UASs, commonly called drones), autonomous underwater vehicles (AUVs), and remotely operated underwater vehicles (ROVs). Using these tools and others, the team will study atmospheric, oceanic, and sea ice properties and processes concurrently. A change in sea ice production will necessarily change the ocean water below, which may have significant consequences for global ocean circulation patterns, a topic of international importance. All the involved institutions will be training students, and all share the goal of expanding climate literacy in the US, emphasizing the role high latitudes play in the Earth's dynamic climate.<br/><br/>The main goal of the project is to improve estimates of sea ice production and water mass transformation in the Ross Sea. The team will fully capture the spatial and temporal changes in air-ice-ocean interactions when they are initiated in the austral fall, and then track the changes into the winter and spring using ice buoys, and airborne mapping with the newly commissioned IcePod instrument system, which is deployed on the US Antarctic Program's LC-130 fleet. The oceanographic cruise will include stations in and outside of both the Terra Nova Bay and Ross Ice Shelf polynyas. Measurements to be made include air-sea boundary layer fluxes of heat, freshwater, and trace gases, radiation, and meteorology in the air; ice formation processes, ice thickness, snow depth, mass balance, and ice drift within the sea ice zone; and temperature, salinity, and momentum in the ocean below. Following collection of the field data, the team will improve both model parameterizations of air-sea-ice interactions and remote sensing algorithms. Model parameterizations are needed to determine if sea-ice production has increased in crucial areas, and if so, why (e.g., stronger winds or fresher oceans). The remote sensing validation will facilitate change detection over wider areas and verify model predictions over time. Accordingly this project will contribute to the international Southern Ocean Observing System (SOOS) goal of measuring essential climate variables continuously to monitor the state of the ocean and ice cover into the future.
Evidence from the eastern Ross Sea continental shelf indicates that the West Antarctic Ice Sheet advanced and retreated during the last glacial cycle, but it is unclear whether the ice sheet advanced to the shelf edge or just to the middle shelf. These two end-member scenarios offer different interpretations as to why, how, and when the West Antarctic Ice Sheet oscillated. The PI proposes to acquire seismic, multibeam, and core data from Whales Deep, to evaluate the timing and duration of two advances of grounded ice to the outer and middle shelf of the Whales Deep Basin, a West Antarctic Ice Sheet paleo ice stream trough in eastern Ross Sea. Grounding events are represented by seismically resolvable Grounding Zone Wedges. The PI will collect radiocarbon dates on in situ benthic foraminifera from the grounding zone diamict as well as ramped pyrolysis radiocarbon dates on acid insoluble organics from open-marine mud overlying the grounding zone diamict. Using these data the PI will calculate the duration of the two grounding events. Furthermore, the PI will test a numerical model prediction that West Antarctic Ice Sheet retreat must have involved melting at the marine terminus of the ice sheet. Pore-water from the grounding zone diamict will be extracted from piston cores to determine salinity and δ18O values that should indicate if significant melting occurred at the grounding line.
The data collected will provide constraints on the timing and pattern of Last Glacial Maximum advance and retreat that can be incorporated into interpretations of ice-surface elevation changes. The proposed activities will provide valuable field and research training to undergraduate/graduate students and a Louisiana high-school science teacher. The research will be interactively shared with middle- and high-school science students and with visitors to the LSU Museum of Natural Science Weekend-Science Program.
In order to understand what environmental conditions might look like for future generations, we need to turn to archives of past times when the world was indeed warmer, before anyone was around to commit them to collective memory. The geologic record of Earth's past offers a glimpse of what could be in store for the future. Research by Ivany and her team looks to Antarctica during a time of past global warmth to see how seasonality of temperature and rainfall in coastal settings are likely to change in the future. They will use the chemistry of fossils (a natural archive of these variables) to test a provocative hypothesis about near-monsoonal conditions in the high latitudes when the oceans are warm. If true, we can expect high-latitude shipping lanes to become more hazardous and fragile marine ecosystems adapted to constant cold temperatures to suffer. With growing information about how human activities are likely to affect the planet in the future, we will be able to make more informed decisions about policies today. This research involves an international team of scholars, including several women scientists, training of graduate students, and a public museum exhibit to educate children about how we study Earth's ancient climate and what we can learn from it.<br/><br/>Antarctica is key to an understanding how Earth?s climate system works under conditions of elevated CO2. The poles are the most sensitive regions on the planet to climate change, and the equator-to-pole temperature gradient and the degree to which high-latitude warming is amplified are important components for climate models to capture. Accurate proxy data with good age control are therefore critical for testing numerical models and establishing global patterns. The La Meseta Formation on Seymour Island is the only documented marine section from the globally warm Eocene Epoch exposed in outcrop on the continent; hence its climate record is integral to studies of warming. Early data suggest the potential for strongly seasonal precipitation and runoff in coastal settings. This collaboration among paleontologists, geochemists, and climate modelers will test this using seasonally resolved del-18O data from fossil shallow marine bivalves to track the evolution of seasonality through the section, in combination with independent proxies for the composition of summer precipitation (leaf wax del-D) and local seawater (clumped isotopes). The impact of the anticipated salinity stratification on regional climate will be evaluated in the context of numerical climate model simulations. In addition to providing greater clarity on high-latitude conditions during this time of high CO2, the combination of proxy and model results will provide insights about how Eocene warmth may have been maintained and how subsequent cooling came about. As well, a new approach to the analysis of shell carbonates for 87Sr/86Sr will allow refinements in age control so as to allow correlation of this important section with other regions to clarify global climate gradients. The project outlined here will develop new and detailed paleoclimate records from existing samples using well-tuned as well as newer proxies applied here in novel ways. Seasonal extremes are climate parameters generally inaccessible to most studies but critical to an understanding of climate change; these are possible to resolve in this well-preserved, accretionary-macrofossil-bearing section. This is an integrated study that links marine and terrestrial climate records for a key region of the planet across the most significant climate transition in the Cenozoic.
This project will investigate the marine component of the Totten Glacier and Moscow University Ice Shelf, East Antarctica. This system is of critical importance because it drains one-eighth of the East Antarctic Ice Sheet and contains a volume equivalent to nearly 7 meters of potential sea level rise, greater than the entire West Antarctic Ice Sheet. This nearly completely unexplored region is the single largest and least understood marine glacial system that is potentially unstable. Despite intense scrutiny of marine based systems in the West Antarctic Ice Sheet, little is known about the Totten Glacier system. This study will add substantially to the meager oceanographic and marine geology and geophysics data available in this region, and will significantly advance understanding of this poorly understood glacial system and its potentially sensitive response to environmental change.<br/><br/>Independent, space-based platforms indicate accelerating mass loss of the Totten system. Recent aerogeophysical surveys of the Aurora Subglacial Basin, which contains the deepest ice in Antarctica and drains into the Totten system, have provided the subglacial context for measured surface changes and show that the Totten Glacier has been the most significant drainage pathway for at least two previous ice flow regimes. However, the offshore context is far less understood. Limited physical oceanographic data from the nearby shelf/slope break indicate the presence of Modified Circumpolar Deep Water within a thick bottom layer at the mouth of a trough with apparent access to Totten Glacier, suggesting the possibility of sub-glacial bottom inflow of relatively warm water, a process considered to be responsible for West Antarctic Ice Sheet grounding line retreat. This project will conduct a ship-based marine geologic and geophysical survey of the region, combined with a physical oceanographic study, in order to evaluate both the recent and longer-term behavior of the glacial system and its relationship to the adjacent oceanographic system. This endeavor will complement studies of other Antarctic ice shelves, oceanographic studies near the Antarctic Peninsula, and ongoing development of ice sheet and other ocean models.
Interest in the reduced alkalinity of high latitude waters under conditions of enhanced CO2 uptake from the atmosphere have been the impetus of numerous recent studies of bio-stressors in the polar marine environment. The project seeks to improve our understanding of the variance of coastal Southern Ocean carbonate species (CO2 system), its diurnal and inter-annual variability, by acquiring autonomous, high frequency observations from an Antarctic coastal mooring(s). <br/><br/>A moored observing system co-located within the existing Palmer LTER array will measure pH, CO2 partial pressure, temperature, salinity and dissolved oxygen with 3-hour frequency in this region of the West Antarctic Peninsula continental shelf. Such observations will help estimate the dominant physical and biological controls on the seasonal variations in the CO2 system in coastal Antarctic waters, including the sign, seasonality and the flux of the net annual air-sea exchange of carbon dioxide. The Palmer LTER site is experiencing rapid ecological change in the West Antarctic Peninsula, a region that is warming at rates faster than any other region of coastal Antarctica.
Intellectual Merit: <br/>This project will determine the potential vulnerability of key ice streams to incursions of warmer ocean water onto the continental shelf and if this mechanism could already explain any of the observed thinning of the ice sheet. It will provide important constrains on ice dynamic of the investigated section of the EAIS, and thus will be critical for future ice sheet models and provide mechanisms for EAIS contributions to past sea level high-stand. The PI proposes to investigate four key ice stream systems on the continental shelf between ~90Â°E and 160Â°E. They will use multibeam bathymetry to identify if and where cross-shelf troughs exist to help determine whether these troughs could provide potential pathways for warmer ocean water. Furthermore, detailed analysis of morphological features of these troughs could provide information on past ice dynamic, maximum extent, and flow direction of related paleo ice streams. The PIs will also conduct water column measurements along these troughs and on the continental slope to determine whether warmer ocean water could enter the shelf in the near future, or if such water has already entered any troughs, and thus might be causing the observed thinning of some ice streams.<br/><br/>Broader impacts: <br/>This project includes the participation and support of undergraduate and graduate students in field work and data analysis. The possible involvement of a PolarTREC teacher and the Earth2Class teachers program will reach out to K-12 students.
The research supported in this project will examine the effects of environmental change on a key Antarctic marine invertebrate, a pelagic mollusk, the pteropod, Limacina helicina antarctica. There are two main activities in this project: (1) to deploy oceanographic equipment ? in this case, autonomously recording pH sensors called SeaFETs and other devices that record temperature and salinity, and (2) to use these environmental data in the laboratory at McMurdo Station to study the response of the marine invertebrates to future changes in water quality that is expected in the next few decades. Notably, changes in oceanic pH (aka ocean acidification) and ocean warming are projected to be particularly threatening to calcifying marine organisms in cold-water, high latitude seas, making tolerance data on these organisms a critical research need in Antarctic marine ecosystems. <br/><br/>These Antarctic shelled-animals are especially vulnerable to dissolution stress from ocean acidification because they currently inhabit seawater that is barely at the saturation level to support biogenic calcification. Indeed, these polar animals are considered to be the 'first responders' to chemical changes in the surface oceans. Thus, this project will lead to information about the adaptive capacity of L. helcina antarctica. From an ecological perspective this is important because this animal is a critical part of the Antarctic food chain in coastal waters and changes in its abundance will impact other species. Finally, the research conducted in this project will serve as a training and educational opportunity for undergraduate and graduate students as well as postdoctoral scholars.
Time series data, from ocean moorings, on key aspects of evolving ocean properties are of considerable importance in assessing the condition of the ocean system. They are needed, for example, their understand how the oceans are warming, and how they continue to uptake greenhouse gases such as CO2. <br/><br/>The Cape Adare Long Term Mooring (CALM) program goal was to observe the bottom water export from the Ross Sea to the deep ocean. To accomplish this two instrumented moorings were set on the continental slope off Cape Adare (western Ross Sea, Antarctica), positioned to capture the export of Antarctic Bottom Water (AABW), some of the coldest and densest water found in the global ocean. Data records for the moorings spans over some four years in this very remote part of the ocean. The CALM analysis will address some specific objectives:<br/>? Characterize the temperature, salinity and current variability associated with the Ross Sea AABW export.<br/>? Examine the linkages between observed variability to regional tides, atmosphere and sea ice forcing.<br/>? Relate the Ross Sea AABW export fluctuations to the larger scale climate system dynamics, such as ENSO and SAM, and to AABW formation along other margins of Antarctica, e.g. the Weddell Sea
The investigators propose to build and test a multi-sensor, automated measurement station for monitoring Arctic and Antarctic ice-ocean environments. The system, based on a previously successful design, will incorporate weather and climate sensors, camera, snow and firn sensors, instruments to measure ice motion, ice and ocean thermal profilers, hydrophone, and salinity sensors. This new system will have two-way communications for real-time data delivery and is designed for rapid deployment by a small field group. <br/><br/>AMIGOS-II will be capable of providing real time information on geophysical processes such as weather, snowmelt, ice motion and strain, fractures and melt ponds, firn thermal profiling, and ocean conditions from multiple levels every few hours for 2-4 years. Project personnel will conduct a field test of the new system at a location with a deep ice-covered lake. Development of AMIGOS-II is motivated by recent calls by the U.S. Antarctic Program Blue-Ribbon Panel to increase Antarctic logistical effectiveness, which cites a need for greater efficiency in logistical operations. Installation of autonomous stations with reduced logistical requirements advances this goal.
The relatively pristine Antarctic continent with its extensive maritime zone represents a unique location on the planet to investigate the long distance aerial transport and deposition of marine microorganisms. The vast extent of new sea ice that forms each winter around the continent results in large numbers of frost flowers, delicate ice-crystal structures of high salt content that form on the surface of the ice and are readily dispersed by wind. The proposed research builds on earlier work in the Arctic and tests the new hypothesis that wind-borne frost flowers provide an effective mechanism for the transport of marine bacteria over long distances, one that can be uniquely sourced and tracked by the frost flower salt signature in the Antarctic realm. A highly resolved genomic snapshot of the microbial community will be acquired at each stage in the transport path, which will track decreasing fractions of the marine microbial community as it freezes into sea ice, incorporates into frost flowers, converts to aerosols, and ultimately deposits within continental snowpack. En route from sea ice to snowpack, marine bacteria will be exposed to an array of environmental stresses, including high salinity, low temperatures, UV light and potential desiccation. A parallel proteomic analysis will enable an evaluation of the microbial response to these extreme conditions and potential survival mechanisms that allow persistence or eventual colonization of deposition sites across Antarctica. <br/><br/>Current understanding of microbes in the Antarctic atmosphere is based on a limited number of microscopic and culture-based assays and a single report of low-resolution 16S RNA gene sequence analysis. The research will broadly impact understanding of atmospheric microbiology, from source to deposition, and various issues of microbial survival, colonization, endemism, and diversity under extreme conditions. In addition to venues that reach the scientific community, the research team will develop a permanent multi-media and artifact-based exhibit on Antarctic Microbial Transport that will be showcased at Seattle's Pacific Science Center (PSC), which educates nearly a million visitors annually.
Lake Vida is the largest lake of the McMurdo Dry Valleys, with an approximately 20 m ice cover overlaying a brine of unknown depth with at least 7 times seawater salinity and temperatures below -10 degrees C year-round. Samples of brine collected from ice above the main water body contain 1) the highest nitrous oxide levels of any natural water body on Earth, 2) unusual geochemistry including anomalously high ammonia and iron concentrations, 3) high microbial counts with an unusual proportion (99%) of ultramicrobacteria. The microbial community is unique even compared to other Dry Valley Lakes. The research proposes to enter, for the first time the main brine body below the thick ice of Lake Vida and perform in situ measurements, collect samples of the brine column, and collect sediment cores from the lake bottom for detailed geochemical and microbiological analyses. The results will allow the characterization of present and past life in the lake, assessment of modern and past sedimentary processes, and determination of the lake's history. The research will be conducted by a multidisciplinary team that will uncover the biogeochemical processes associated with a non-photosynthetic microbial community isolated for a significant period of time. This research will address diversity, adaptive mechanisms and evolutionary processes in the context of the physical evolution of the environment of Lake Vida. Results will be widely disseminated through publications, presentations at national and international meetings, through the Subglacial Antarctic Lake Exploration (SALE) web site and the McMurdo LTER web site. The research will support three graduate students and three undergraduate research assistants. The results will be incorporated into a new undergraduate biogeosciences course at the University of Illinois at Chicago which has an extremely diverse student body, dominated by minorities.
Hofmann, Eileen; Klinck, John M.; Dinniman, Michael
No dataset link provided
Abstract<br/><br/>This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).<br/><br/>The Ross Sea is a highly productive area within the Southern Ocean, but it experiences substantial variability in both physical (temperature, ice concentrations, salinity, winds, and current velocities) and biogeochemical (chlorophyll, productivity, micronutrients, higher trophic level standing stocks, gases, etc.) conditions. Understanding the temporal and spatial oceanographic variations in physical forcing is essential to understanding the ecological functioning within the Ross Sea. There are a number of models of the physical oceanography of the Ross Sea that characterize the observed circulation. Unfortunately, data on the appropriate time scales (daily, monthly, seasonal, and interannual) to completely evaluate those models are lacking. The proposed research is a demonstration project to characterize the physical and biological oceanography of the southern Ross Sea using newly developed Glider technology to sample the region continuously through the growing season, to collect temperature, salinity, fluorescence, oxygen and optical transmission data. These field data will be used to assist in evaluation of an eddy-resolving ROMS-based coupled circulation-biological model, and, along with satellite ocean color information, will be assimilated into an ecosystem model. Data assimilation techniques will reduce the model uncertainties of the circulation and food webs of the region. The intellectual merit of this effort arises from the combination of field-based investigations using a novel technology (one that is far more cost-effective than ship-based studies) with state-of-the-art biological-physical models and advanced data assimilation techniques. The research will provide new insights into the complex oceanographic phenomena of the Antarctic continental shelves and is a novel method of continuing the studies of the southern Ross Sea. Broader impacts of the proposed research include training of graduate and undergraduate students and partnership with several ongoing outreach programs dealing with scientific research in the Southern Ocean. At least 2 graduate students will be supported by this research, and it will be a critical component of a variety of outreach programs in Virginia, including a High School Marine Science Day, Boy and Girl Scout education, and middle school curriculum improvement. The investigators also will create a web site to foster immediate release of the data collected by the glider, and seek a linkage with schools at various levels (middle, high school and Universities) that potentially could incorporate the data into classroom activities
Abstract <br/>This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). <br/><br/>Marine mammals of the Southern Ocean have evolved diverse life history patterns and foraging strategies to accommodate extreme fluctuations in the physical and biological environment. In light of ongoing climate change and the dramatic shifts in the extent and persistence of sea ice in the Ross Sea, it is critical to understand how Weddell seals, Leptonychotes weddellii, a key apex predator, select and utilize foraging habitats. Recent advances in satellite-linked animal-borne conductivity, temperature and depth (CTD) tags make it possible to simultaneously collect data on seal locations, their diving patterns, and the temperature and salinity profiles of the water columns they utilize. In other ecosystems, such data have revealed that marine predators selectively forage in areas where currents and fronts serve to locally concentrate prey resources, and that these conditions are required to sustain populations. Weddell seals will be studied in McMurdo Sound and at Terra Nova Bay, Ross Sea and will provide the first new data on Weddell seal winter diving behavior and habitat use in almost two decades. The relationship between an animal's diving behavior and physical habitat has enormous potential to enhance monitoring studies and to provide insight into how changes in ice conditions (due either to warming or the impact of large icebergs, such as B15) might impact individual time budgets and foraging success. The second thrust of this project is to use the profiles obtained from CTD seal tags to model the physical oceanography of this region. Current mathematical models of physical oceanographic processes in the Southern Ocean are directed at better understanding the role that it plays in global climate processes, and the linkages between physical and biological oceanographic processes. However, these efforts are limited by the scarcity of oceanographic data at high latitudes in the winter months; CTD tags deployed on animals will collect data at sufficient spatial and temporal resolution to improve data density. The project will contribute to two IPY endorsed initiatives: MEOP (Marine Mammals as Explorers of the Ocean Pole to Pole) and CAML (Census of Antarctic Marine Life). In addition, the highly visual nature of the data and analysis lends itself to public and educational display and outreach, particularly as they relate to global climate change, and we have collaborations with undergraduate and graduate training programs, the Seymour Marine Discovery Center, and the ARMADA program to foster these broader impacts.
Several aspect of the seasonal melting and reformation cycle of Antarctic sea ice appear to be divergent from those occurring in the Arctic. This is most clearly demonstrated by the dramatic diminishing extent and thinning of the Arctic sea ice, to be contrasted to the changes in Antarctic sea-ice extent, which recently (decadaly) shows small increases. Current climate models do not resolve this discrepancy which likely results from both a lack of relevant observational sea-ice data in the Antarctic, along with inadequacies in the physical parameterization of sea-ice properties in climate models.<br/><br/>Researchers will take advantage of the cruise track of the I/B Oden during transit through the Antarctic sea-ice zones in the region of the Bellingshausen, Amundsen and Ross (BAR) seas on a cruise to McMurdo Station. Because of its remoteness and inaccessibility, the BAR region is of considerable scientific interest as being one of the last under described and perhaps unexploited marine ecosystems left on the planet .<br/><br/>A series of on station and underway observations of sea ice properties will be undertaken, thematically linked to broader questions of summer ice survival and baseline physical properties (e.g. estimates of heat and salt fluxes). In situ spatiotemporal variability of sea-ice cover extent, thickness and snow cover depths will be observed.
Studinger/0636584<br/><br/>This award supports a project to estimate the salinity of subglacial Lake Vostok, Lake Concordia and the 90 deg.E lake using existing airborne ice-penetrating radar and laser altimeter data. These lakes have been selected because of the availability of modern aerogeophysical data and because they are large enough for the floating ice to be unaffected by boundary stresses near the grounding lines. The proposed approach is based on the assumption that the ice sheet above large subglacial lakes is in hydrostatic equilibrium and the density and subsequently salinity of the lake's water can be estimated from the (linear) relationship between ice surface elevation and ice thickness of the floating ice. The goal of the proposed work is to estimate the salinity of Lake Vostok and determine spatial changes and to compare the salinity estimates of 3 large subglacial lakes in East Antarctica. The intellectual merits of the project are that this work will contribute to the knowledge of the physical and chemical processes operating within subglacial lake environments. Due to the inaccessibility of subglacial lakes numerical modeling of the water circulation is currently the only way forward to develop a conceptual understanding of the circulation and melting and freezing regimes in subglacial lakes. Numerical experiments show that the salinity of the lake's water is a crucial input parameter for the 3-D fluid dynamic models. Improved numerical models will contribute to our knowledge of water circulation in subglacial lakes, its effects on water and heat budgets, stratification, melting and freezing, and the conditions that support life in such extreme environments. The broader impacts of the project are that subglacial lakes have captured the interest of many people, scientists and laymen. The national and international press frequently reports about the research of the Principal Investigator. His Lake Vostok illustrations have been used in math and earth science text books. Lake Vostok will be used for education and outreach in the Earth2Class project. Earth2Class is a highly successful science/math/technology learning resource for K-12 students, teachers, and administrators in the New York metropolitan area. Earth2Class is created through collaboration by research scientists at the Lamont- Doherty Earth Observatory; curriculum and educational technology specialists from Teachers College, Columbia University; and classroom teachers in the New York metropolitan area.
The primary objective of this research is to investigate polar marine psychrophilic bacteria for their potential to nucleate ice using a combination of microbiological, molecular biological and atmospheric science approaches in the laboratory. Very little is known about how psychrophiles interact and cope with ice or their adaptations to conditions of extreme cold and salinity. This work will involve a series of laboratory experiments using a novel freeze-tube technique for assaying freezing spectra which will provide quantitative information on: (i) the temperature-dependent freezing rates for heterogeneously frozen droplets containing sea-ice bacteria, (ii) the proportional occurrence of ice-nucleation activity versus anti-freeze activity among sea-ice bacterial isolates and (iii) the temperature-dependent freezing rates of bacteria with ice-nucleation activity grown at a range of temperatures and salinities. The compound(s) responsible for the observed activity will be identified, which is an essential step towards the development of an in-situ bacterial ice-nucleation detection assay that can be applied in the field to Antarctic water and cloud samples.<br/> One of the goals of this work is to better understand survival and cold adaptation processes of polar marine bacteria confronted with freezing conditions in sea ice. Since sea ice strongly impacts polar, as well as the global climates, this research is of significant interest because it will also provide data for accessing the importance of bacterial ice nucleation in the formation of sea ice. These measurements of ice-nucleation rates will be the first high-resolution measurements for psychrophilic marine bacteria. Another goal is to better understand the impact of bacterial ice initiation processes in polar clouds by making high-resolution measurements of nucleation rates for cloud bacteria found over Arctic and Antarctic regions. Initial measurements indicate these bacteria nucleate ice at warmer temperatures and the effect in polar regions may be quite important, since ice can strongly impact cloud dynamics, cloud radiative properties, precipitation formation, and cloud chemistry. If these initial measurements are confirmed, the data collected here will be important for improving the understanding of polar cloud processes and models. A third goal is to better understand the molecular basis of marine bacterial ice nucleation by characterizing the ice-nucleation compound and comparing it with those of known plant-derived ice-nucleating bacteria, which are the only ice-nucleating bacteria examined in detail to date. The proposed activity will support the beginning academic career of a post-doctoral researcher and will serve as the basis for several undergraduate student laboratory projects. Results from this research will be widely published in various scientific journals and outreach venues.
This project is an investigation into one mechanism by which deep ocean convection can evolve from stable initial conditions, to the extent that it becomes well enough established to bring warm water to the surface and melt an existing ice cover in late, or possibly even mid-winter. The specific study will investigate how the non-linear dependence of seawater density on temperature and salinity (the equation of state) can enhance vertical convection under typical antarctic conditions. When layers of seawater with similar densities but strong contrasts in temperature and salinity interact, there are a number of possible non-linear instabilities that can convert existing potential energy to turbulent energy. In the Weddell Sea, a cold surface mixed layer is often separated from the underlying warm, more saline water by a thin, weak pycnocline, making the water column particularly susceptible to an instability associated with thermobaricity (the pressure dependence of the thermal expansion coefficient). The project is a collaboration between New York University, Earth and Space Research, the University of Washington, the Naval Postgraduate School, and McPhee Research Company.<br/>The work has strong practical applications in contributing to the explanation for the existence of the Weddell Polynya, a 300,000 square kilometer area of open water within the seasonal sea ice of the Weddell Sea, from approximately 1975 to 1979. It has not recurred since, although indications of much smaller and less persistent areas of open water do occur in the vicinity of the Maud Rise seamount. <br/> The experimental component will be carried out on board the RVIB Nathaniel B. Palmer between July and September, 2005.
This study will investigate how the formation of dense water masses on the antarctic continental shelves is affected by the periodic flushing by relatively warm circumpolar deep water, and whether the intrusion of warm water cna enhance the rate of formation of dense antarctic water. The study involves the observation of water mass modification processes on the continental shelf off the Adelie Coast in East Antarctica, near a quasi-permanent area of open water in the vicinity of the Mertz and Ninnis Glacier tongues - the so-called Mertz polynya.<br/><br/>Antarctic coastal polynyas, formed by strong offshore winds, are often referred to as major sea ice and salt "factories" because the newly formed ice is blown seaward, allowing more ice to be formed along the coast, and because the freezing process increases the salinity of the continental shelf water. The thin ice, or even open water, implies significant heat losses from the ocean to the atmosphere, which also increases the density of the shelf water. The shelf water sinks, fills any depressions in the bottom, and is gravitationally driven down the continental slope. An additional process is identified for this study and is expected to be at work in this area: the intrusion of relatively warm water onto the continental shelf, overriding the shelf water and essentially shutting down the densification processes.<br/><br/> The study will make use of the RVIB Nathaniel B. Palmer to obtain a closely spaced array of hydrographic stations over the continental shelf and slope along the George V Coast in the austral summer. The dat obtained here will complement a similar winter study by the Australian National Antarctic Program.<br/>***
This project is a study of the effects of antarctic sea ice in the global climate system, through an examination of how the spatial distribution of ice and snow thickness and of open water is reflected in satellite-based synthetic aperture radar (SAR) imagery. The field investigations will be carried out from the RVIB Nathaniel B. Palmer in winter 1998 and summer 1999, and will produce observations of the snow and ice distribution, the crystal structure, stable isotopes, salinity and temperature structure of ice cores, and the stratigraphy, grain size, and water content of the snow cover. The SAR images from ERS-2 and RADARSAT will be acquired at the McMurdo ground station, and processed at the Alaska SAR Facility. These will provide information about the large-scale ice motion field and the small-scale ice deformation field, both of which contribute to the observed ice thickness distribution. In addition, a study of the spatial and temporal variation of the backscattered microwave energy will contribute to the development of numerical models that simulate the dynamic and thermodynamic interactions among the sea ice, ocean, and atmosphere. The surface data is vital for the extraction of environmental information from the radar data, and for the ultimate validation of interactive models.
9528807 Gordon The proposed project is part of a multi-institutional integrated study of the outflow of newly formed bottom water from the Weddell Sea and its dispersion into the South Atlantic Ocean. It builds upon earlier successful studies of the inflow of intermediate water masses into the Eastern Weddell Sea, their modification within the Weddell Gyre, and their interaction with bottom water formation processes in the western Weddell Sea. The study is called Deep Ocean Ventilation Through Antarctic Intermediate Layers (DOVETAIL) and includes six components involving hydrographic measurements, natural tracer experiments, and modeling studies. The study will be centered east of the Drake Passage where water masses from the Weddell Sea and the Scotia Sea come together in the Weddell-Scotia Confluence, and will be carried out in cooperation with the national antarctic programs of Germany and Spain. This particular component concerns observations of the temperature and salinity structure, as well as the chemical nature of the water column in the confluence region. The study has four related objectives. The first is to assess the quantity and the physical and chemical characteristics of Weddell Sea source waters for the confluence. The second is to describe the dominant processes associated with spreading and sinking of dense antarctic waters within the Weddell-Scotia Confluence. The third is to estimate the ventilation rate of the world ocean, and the fourth is to estimate seasonal fluctuations in the regional ocean transport and hydrographic structure and to assess the likely influence of seasonal to interannual variability on rates of ventilation by Weddell Sea waters. Ventilation of the deep ocean -- the rising of sub-surface water masses to the surface to be recharged with atmospheric gases and to give up heat to the atmosphere -- is a uniquely antarctic phenomenon that has significant consequences for global change by affecting the g lobal reservoir of carbon dioxide, and by modulating the amount and extent of seasonal sea ice in the southern hemisphere. This component will make systematic observations of the temperature salinity structure of the water and undertake an extensive sampling program for other chemical studies. The purpose is to identify the individual water masses and to relate their temperature and salinity characteristics to the modification processes within the Weddell Sea. ***
The goal of this investigation is to understand the role of snow in sea ice development processes and air-ice-ocean heat exchange interactions in the seasonal and perennial sea ice zones of the Ross Sea, the Amundsen Sea, and the Bellingshausen Sea. Observations and measurements of the characteristics of sea ice and snow will be combined with numerical models of sea-ice flooding and the entrainment of snow into the ice cover in order to gain an understanding of the sea-ice heat and mass balance, and to quantify the energy exchange within the antarctic sea-ice cover. The snow measurement program, using the RVIB Nathaniel B. Palmer, will include depth, grain size and morphology, density, temperature, thermal conductivity, water content, and stable isotope ratio. The ice measurement program will include thickness, salinity, temperature, density, brine content, and included gas volume, as well as such structural properties as the fraction of frazil, platelet, and congelation ice in the seasonal antarctic pack ice. Differences in ice types are the result of differences in the environment in which the ice forms: frazil ice is formed in supercooled sea water, normally through wind or wave-induced turbulence, while platelet and congelation ice is formed under quiescent conditions. The fraction of frazil ice is an important variable in the energy budget of the upper ocean, and contributes significantly to the stabilization of the surface layers. The numerical models will involve the thermodynamics of phase changes from liquid water to ice, along with the resulting energy transfer, brine expulsion, and the modulating effect of a snow cover. The results are expected to have broad relevance and application to understanding the effects of sea-ice processes in global change, and atmospheric, oceanographic, and remote sensing investigations of the Southern Ocean.
This project is an examination of the physical and structural properties of the antarctic ice pack in the Amundsen, Bellingshausen, and Ross Seas, with the goal of defining the geographical variability of various ice types, the deformation processes that are active in the antarctic ice pack, and the large-scale thermodynamics and heat exchange processes of the ice- covered Southern Ocean. An additional goal is to relate specific characteristics of antarctic sea ice to its synthetic aperture radar (SAR) signature as observed from satellites. Physical properties include the salinity, temperature, and brine volumes, while structural properties include the fraction of frazil, platelet, and congelation ice of the seasonal antarctic pack ice. Differences in ice types are the result of differences in the environment in which the ice forms: frazil ice is formed in supercooled sea water, normally through wind or wave-induced turbulence, while platelet and congelation ice is formed under quiescent conditions. The fraction of frazil ice (which has been observed to be generally in excess of 50% in Weddell Sea ice floes) is an important variable in the energy budget of the upper ocean, and contributes significantly to the stabilization of the surface layers. The integration of sea ice field observations and synthetic aperture radar data analysis and modeling studies will contribute to a better understanding of sea ice parameters and their geophysical controls, and will be useful in defining the kind of air-ice-ocean interactions that can be studied using SAR data, as well as having broader relevance and application to atmospheric, biological, and oceanographic investigations of the Southern Ocean.
This project will be the first systematic oceanographic study of the continental shelves of the Amundsen and Bellings-hausen Seas, and will include temperature and salinity profiling, water sampling for ocean chemistry, and continuous precision bathymetry. Upwelling warm deep water covers the Amundsen and Bellings-hausen shelves and delivers significant amounts of heat to the sea ice and fringing ice shelves. The regional precipitation is heavy, and has historically maintained a perennial ice cover. However, within the last few years satellite images have shown that the ice has been receding dramatically, with large areas of open water persisting through the winter in sectors that earlier had been ice-covered. These anomalous ice distributions are likely to have been accompanied by altered surface water properties, and possibly changes in the deep vertical circulation. There are indications that the conditions favoring a reduction in the sea ice may migrate westward toward the Ross Sea, and may have influenced a gradual warming over recent decades on the western side of the Antarctic Peninsula. The project will make use of the R/V Nathaniel B. Palmer in two cruises; one in the late austral summer 1993-1994, and a subse- quent cruise in September and October to observe late winter conditions.
This project is a two-year investigation into the dynamics and processes of deep water mass formation in the western Weddell Sea, combining physical and chemical oceanographic techniques to produce a coherent picture of the importance of this unique region to the structure of the world ocean. In the global context, this area is a major water mass modification site, involving open ocean convective events, the continental margin, and the ice cover. At this time the various water types that combine to form Weddell Sea Deep Water and Antarctic Bottom Water, and the conditions under which these water masses form, are not known well enough to establish direct physical links and volumetric budgets. It is suspected that the outflow from the Weddell Sea is restricted to quite narrow boundary currents flowing near the base of the continental shelf, and consequently may be observed with conventional current meter moorings from the shelf into the deep ocean. Two oceanographic expeditions to the western Weddell Sea are planned as part of this study: the first in the 1990/91, and the second in 1991/92. The objectives will be to measure the flow of newly-formed bottom water and to explore the sinking process of near-surface waters in the open ocean to see how these affect the deep water flows. In the first year the primary objective will be to set out an array of eight current meters in the bottom water core, while a secondary objective will be to grapple for an existing array that was set out in early 1988 but could not be recovered in 1989 because Antarctic Program ship resources had to be diverted to deal with the oil spill at Palmer Station. In the second year the array will be retrieved. Hydrographic cruises in order to define the upper ocean temperatures and salinity structure in the outflow region where unusually large step structures have been found in the past. A chemistry program consistent with the objectives of the World Ocean Circulation Experiment (WOCE) and presently planned experiments in the South Atlantic Ocean, will be integrated into the cruises carried out under this project.
As long-lived animals, marine mammals must be capable of accommodating broad variations in food resources over large spatial and temporal scales. While this is true of all marine mammals, variation in the physical and biological environmental is particularly profound in the Southern Ocean. A basic understanding of the foraging behavior and habitat utilization of pelagic predators requires knowledge of this spatial and temporal variation, coupled with information of how they respond to these changes. Current understanding of these associations is primarily limited to population level studies where animal abundance has been correlated with oceanography. Although these studies are informative, they cannot provide insights into the strategies employed by individual animals nor can they provide insights into the spatial or temporal course of these interactions. <br/><br/>Recent technological advances in instrumentation make it possible to extend an understanding beyond the simple linkage of prey and predator distributions with environmental features. The key to understanding the processes that lead to high predator abundance is the identification of the specific foraging behaviors associated with different features of the water column. This study will accomplish these objectives by combining accurate positional data, measures of diving and foraging behavior, animal-derived water-column temperature and salinity data, and available oceanographic data. This project will examine the foraging behavior and habitat utilization of two species of contrasting foraging ecology, the southern elephant seal, Mirounga leonina, and the crabeater seal, Lobodon carcinophagus in the Western Antarctic Peninsula, a region of strong environmental gradients. Although these two species are phylogenetically related, they utilize substantially different but adjacent habitat types. Southern elephant seals are predominantly pelagic, moving throughout the southern ocean, venturing occasionally into the seasonal pack ice whereas crabeater seals range throughout the seasonal pack ice, venturing occasionally into open water. The relationship of specific foraging behaviors and animal movement patterns to oceanographic and bathymetric features develop and test models of the importance of these features in defining habitat use will be determined along with a comparison of how individuals of each species respond to annual variability in the marine environment. The physical oceanography of the Southern Ocean is inherently complex as are the biological processes that are intrinsically linked to oceanographic processes. Significant resources are currently being directed toward developing mathematical models of physical oceanographic processes with the goals of better understanding the role that the Southern Ocean plays in global climate processes, predicting the responses of ocean and global scale processes to climate change, and understanding the linkages between physical and biological oceanographic processes. These efforts have been limited by the scarcity of oceanographic data in the region, especially at high latitudes in the winter months. This study will provide new and significant oceanographic data on temperature and salinity profiles in to further the understanding of the dynamics of the upper water column of west Antarctic Peninsula continental shelf waters. Outreach activities include website development and an association with a marine education program at the Monterrey Bay Aquarium Research Institute.
This project is a contribution to a coordinated attempt to understand the interactions of biological and physical dynamics by developing relationships among the evolution of the antarctic winter ice and snow cover, biological habitat variability, and the seasonal progression of marine ecological processes. The work will be carried out in the context of the Southern Ocean Experiment of the Global Ocean Ecosystem Dynamics Study (Globec), a large, multi-investigator study of the winter survival strategy of krill under the antarctic sea ice in the vicinity of Marguerite Bay on the western side of the Antarctic Peninsula.<br/><br/>The objective of this project is to make a quantitative assessment of the small scale temperature and salinity structure of the oceanic surface layer in order to study the effect of stratification and turbulence on the biochemical and biological processes under the winter sea ice.<br/><br/>The water masses on the continental shelf off Marguerite Bay consist of inflowing Upper Circumpolar Deep Water, which is relatively warm, salty, oxygen-poor, and nutrient-rich. In winter atmospheric processes cool and freshen this water, and recharge it with oxygen to produce Antarctic Surface Water which is diffused seaward, and supports both a sea ice cover and a productive krill-based food web. The modification processes work through mixing associated with shear instabilities of the internal wave field, double diffusion of salt and heat, and mixing driven by surface stress and convection. These processes will be quantified with two microstructure profilers, capable of resolving the small but crucial vertical variations that drive these processes.<br/>***
This project will study the dynamics of Circumpolar Deep Water intruding on the continental shelf of the West Antarctic coast, and the effect of this intrusion on the production of cold, dense bottom water, and melting at the base of floating glaciers and ice tongues. It will concentrate on the Amundsen Sea shelf, specifically in the region of the Pine Island Glacier, the Thwaites Glacier, and the Getz Ice Shelf. Circumpolar Deep Water (CDW) is a relatively warm water mass (warmer than +1.0 deg Celsius) which is normally confined to the outer edge of the continental shelf by an oceanic front separating this water mass from colder and saltier shelf waters. In the Amundsen Sea however, the deeper parts of the continental shelf are filled with nearly undiluted CDW, which is mixed upward, delivering significant amounts of heat to the base of the floating glacier tongues and the ice shelf. The melt rate beneath the Pine Island Glacier averages ten meters of ice per year with local annual rates reaching twenty meters. By comparison, melt rates beneath the Ross Ice Shelf are typically twenty to forty centimeters of ice per year. In addition, both the Pine Island and the Thwaites Glacier are extremely fast-moving, and have a significant effect on the regional ice mass balance of West Antarctica. This project therefore has an important connection to antarctic glaciology, particularly in assessing the combined effect of global change on the antarctic environment. The particular objectives of the project are (1) to delineate the frontal structure on the continental shelf sufficiently to define quantitatively the major routes of CDW inflow, meltwater outflow, and the westward evolution of CDW influence; (2) to use the obtained data set to validate a three-dimensional model of sub-ice ocean circulation that is currently under construction, and (3) to refine the estiamtes of in situ melting on the mass balance of the antarctic ice sheet. The observational program will be carried out from the research vessel Nathaniel B. Palmer in February and March, 1999. ***
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's 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.<br/>The 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.
Abstract<br/><br/>The project goal is to investigate the ocean-atmosphere-ice (OAI) interactions in the Amundsen and Ross Seas during the austral summer of 2007-08 using hydrographic measurements (CTD and XBT) in conjunction with (1) ship-based observations and satellite-derived estimates of sea ice concentration, and (2) ship-based observations and re-analyses of meteorological variables. The major scientific objectives are as follows: (1) to examine upper ocean characteristics along three transects in the Amundsen Sea and two transects in the Ross Sea within the context of ice-atmosphere variability over the preceding winter-spring season and as compared to other years where data are available; (2) to determine if there is additional evidence of increased upwelling of warm Circumpolar Deep Water onto the shelf in the Amundsen Sea and/or increased freshening in the Ross Sea as has been inferred by previous, but limited, ocean surveys in these regions; and (3) to examine the spatial variability in ocean thermal structure along the ship's track (outside the transects) to provide greater regional context and to compare with ocean XBT data collected during Oden 2006-07. A repeated temperature survey between the Amundsen and Ross Sea is particularly invaluable, given that this sector is the regional center of the high latitude OAI response to ENSO, thus providing opportunity for examining and linking regional oceanic temporal variability to global climate variability. The research will improve our understanding of the high latitude OAI response to climate change, and provide the physical context for the observed biology and geochemistry (investigated by our colleagues. Our results will be made widely available through research publications and internet-available databases, and through the strong public outreach efforts of Lamont-Doherty Earth Observatory. The outreach efforts will help increase awareness and understanding of anthropogenic climate change, melting ice, and ecosystem alteration in the highly sensitive Antarctic.
Abstract<br/>This project studies microfossils of plants and algae to understand climate during the earliest glaciations of Antarctica. The microfossils are from marine sediment cores collected by the 2006 SHALDRIL campaign to the Antarctic Peninsula. The work will offer constraints on sea surface temperature, ocean salinity, and terrestrial vegetation to help answer questions such as: What were conditions like on the Antarctic Peninsula during the initial formation of Antarctica's ice sheets? How rapidly did the ice sheets grow? Was their growth driven by global factors such as low atmospheric CO2 or local events like opening of the Drake Passage? <br/><br/>The broader impacts include postdoctoral fellow research and outreach via a museum exhibit and a web-based activity book for children.
Abstract<br/><br/>The research will continue and extend the study in the Southern Ocean that was initiated during the Oden Southern Ocean 2006 expedition in collaboration with Swedish scientist Mellissa Chierici. We will quantify carbon flux through the food web in the marginal ice zone (MIZ) by measuring size fractionated primary and secondary production, grazing and carbon flux through nanoplankton (2-20 um), microplankton (20-200um), and mesoplankton (200-2000 um). Community structure, species abundance and size specific grazing rates will be quantified using a variety of techniques both underway and at ice stations along the MIZ. The proposed cruise track extends across the Drake Passage to the Western Antarctic Peninsula (WAP) with three station transects along a gradient from the open ocean through the marginal ice zone (MIZ) in the Bellinghausen and Amundsen Seas and into the Ross Sea Polynya. Ice stations along each transect will provide material to characterize production associated with annual ice. Underway measurements of primary and secondary production (chlorophyll, CDOM, microplankton, and mesoplankton) and hydrography (temperature, salinity, pH, DO, turbidity) will establish a baseline for future cruises and as support for other projects such as biogeochemical studies on carbon dioxide drawdown and trace metal work on primary production. The outcome of these measurements will be a description of nano to mesoplankton standing stocks, community structure, and carbon flux along the MIZ in the Bellinghausen and Amundsen Seas and the Ross Sea Polynya.
Polar terrestrial environments are often described as deserts, where water availability is recognized as one of the most important limits on the distribution of terrestrial organisms. In addition, prolonged low winter temperatures threaten survival, and summer temperatures challenge organisms with extensive diel variations and rapid transitions from freezing to desiccating conditions. Global warming has further impacted the extreme thermal and hydric conditions experienced by Antarctic terrestrial plant and arthropod communities, especially as a result of glacial retreat along the Antarctic Peninsula. This research will focus on thermal and hydric adaptations in the terrestrial midge, Belgica antarctica, the largest and most southerly holometabolous insect living in this challenging and changing environment. <br/>Overwintering midge larvae encased in the frozen substrate must endure desert-like conditions for more than 300 days since free water is biologically unavailable as ice. During the summer, larvae may be immersed in melt water or outwash from penguin colonies and seal wallows, in addition to saltwater splash. Alternatively, the larvae may be subjected to extended periods of desiccation as their microhabitats dry out. Due to their small size, relative immobility and the patchiness of suitable microhabitats, larvae may thus be subjected to stresses that include desiccation, hypo- or hyperosmotic conditions, high salinity exposure, and anoxia for extended periods. Research efforts will focus in three areas relevant to the stress tolerance mechanisms operating in these midges:(1) obtaining a detailed characterization of microclimatic conditions experienced by B. antarctica, especially those related to thermal and hydric diversity, both seasonally and among microhabitat types in the vicinity of Palmer Station, Antarctica; (2) examining the effects of extreme fluctuations in water availability and effects on physiological and molecular responses - to determine if midge larvae utilize the mechanism of cryoprotective dehydration for winter survival, and if genes encoding heat shock proteins and other genes are upregulated in larval responses to dehydration and rehydration; (3) investigating the dietary transmission of cryoprotectants from plant to insect host, which will test the hypothesis that midge larvae acquire increased resistance to desiccation and temperature stress by acquiring cryoprotectants from their host plants. <br/>This project will provide outreach to both elementary and secondary educators and their students. The team will include a teacher who will benefit professionally by full participation in the research, and will also assist in providing outreach to other teachers and their students. From Palmer Station, the field team will communicate daily research progress by e-mail supplemented with digital pictures with teachers and their elementary students to stimulate interest in an Antarctic biology and scientific research. These efforts will be supplemented with presentations at local schools and national teacher meetings, and by publishing hands-on, inquiry-based articles related to cryobiology and polar biology in education journals. Furthermore, the principal investigators will maintain major commitments to training graduate students and postdoctoral scholars, as well as undergraduate students by providing extended research experience that includes publication of scientific papers and presentations at national meetings.
The Antarctic Peninsula (AP) is characterized by (1) the most rapid recent regional (winter) warming (5.35 times global mean), (2) a loss of nearly all its perennial sea ice cover on its western margin, and (3) 87% of the glaciers in retreat, contributing to global sea level rise. An ability to understand this change depends upon researchers' ability to better understand the underlying sources of this change and their driving mechanisms. Despite intensive efforts, the western AP (WAP) is chronically under-sampled. Therefore developing a capability to maintain a sustained in situ presence is a high scientific priority. The current proposal addresses this critical need through 2 objectives: (1) establish the feasibility of a Slocum Webb ocean glider to enable real-time high resolution data-adaptive polar oceanographic research; (2) address a critical question involving the regional climate change by measuring the ocean heat budget within a grid containing 14 years of ship-based ocean snapshots. This will involve the launch of the glider during the PAL-LTER austral summer research cruise, where it will fly the full along-shore distance of the LTER sample grid to be recovered at the southern extreme when the ship arrives there later in the summer. The glider will provide nearly continuous ocean property (temperature, salinity and pressure) coverage over this distance.<br/><br/>Intellectual merit. The proposed activity will involve state of the art sampling methodology that will revolutionize the ability to address climate change and other scientific issues requiring sampling densities that could not be achieved by research vessels. Specifically, the adaptive sampling capability of the glider will be used to alter its course allowing identification of routes by which the source waters of the ocean heat (and nutrients) enter the continental shelf region, while the near-continuous sampling will provide a diagnosis of how well standard shipborne stations close the heat budget. Resources are adequate for this study due to heavy leveraging by the availability of the Rutgers SLOCUM Web glider, glider control center and participation of the team of experts that flew the first such glider.<br/><br/>Broader Impacts. The proposed activity will advance discovery and understanding of the WAP responses to climate variability, to study the intricate feedback mechanisms associated with this variability and to better understand the chemical and physical processes associated with climate change. The data will be made available across the World Wide Web as it is collected, almost in real time, a potential bonanza for scientists during the upcoming International Polar Year, for classroom instruction and general outreach. Society will ultimately benefit from the improved knowledge of how climate change elsewhere in the world is impacting the unique ecosystem of the Antarctic, and driving glacial melt (sea level rise), among its other influences.