{"dp_type": "Project", "free_text": "CO2 Concentrations"}
[{"awards": "1043623 Miller, Scott", "bounds_geometry": "POLYGON((117.5 -47,120.35 -47,123.2 -47,126.05 -47,128.9 -47,131.75 -47,134.6 -47,137.45 -47,140.3 -47,143.15 -47,146 -47,146 -49.04,146 -51.08,146 -53.12,146 -55.16,146 -57.2,146 -59.24,146 -61.28,146 -63.32,146 -65.36,146 -67.4,143.15 -67.4,140.3 -67.4,137.45 -67.4,134.6 -67.4,131.75 -67.4,128.9 -67.4,126.05 -67.4,123.2 -67.4,120.35 -67.4,117.5 -67.4,117.5 -65.36,117.5 -63.32,117.5 -61.28,117.5 -59.24,117.5 -57.2,117.5 -55.16,117.5 -53.12,117.5 -51.08,117.5 -49.04,117.5 -47))", "dataset_titles": "Eddy covariance air-sea momentum, heat, and carbon dioxide fluxes in the Southern Ocean from the N.B. Palmer cruise NBP1210; Eddy covariance air-sea momentum, heat, and carbon dioxide fluxes in the Southern Ocean from the N.B. Palmer cruise NBP1402; Expedition Data", "datasets": [{"dataset_uid": "001427", "doi": "", "keywords": null, "people": null, "repository": "R2R", "science_program": null, "title": "Expedition Data", "url": "https://www.rvdata.us/search/cruise/NBP1210"}, {"dataset_uid": "001414", "doi": "", "keywords": null, "people": null, "repository": "R2R", "science_program": null, "title": "Expedition Data", "url": "https://www.rvdata.us/search/cruise/NBP1402"}, {"dataset_uid": "601308", "doi": null, "keywords": "Air-Sea Flux; Air Temperature; Antarctica; Atmosphere; CO2; CO2 Concentrations; East Antarctica; Flux; Meteorology; NBP1402; Oceans; Relative Humidity; Salinity; Totten Glacier; Water Measurements; Water Temperature; Weather Station Data; Wind Direction; Wind Speed", "people": "Miller, Scott; Butterworth, Brian", "repository": "USAP-DC", "science_program": null, "title": "Eddy covariance air-sea momentum, heat, and carbon dioxide fluxes in the Southern Ocean from the N.B. Palmer cruise NBP1402", "url": "https://www.usap-dc.org/view/dataset/601308"}, {"dataset_uid": "601309", "doi": "10.15784/601309", "keywords": "Air-Sea Flux; Air Temperature; Amundsen Sea; Antarctica; Antarctic Peninsula; Atmosphere; CO2; Flux; Meteorology; NBP1210; Oceans; Ross Sea; R/v Nathaniel B. Palmer; Southern Ocean; Water Temperature; Wind Direction; Wind Speed", "people": "Miller, Scott; Butterworth, Brian", "repository": "USAP-DC", "science_program": null, "title": "Eddy covariance air-sea momentum, heat, and carbon dioxide fluxes in the Southern Ocean from the N.B. Palmer cruise NBP1210", "url": "https://www.usap-dc.org/view/dataset/601309"}], "date_created": "Fri, 09 Oct 2020 00:00:00 GMT", "description": "Accurate parameterizations of the air-sea fluxes of CO2 into the Southern Ocean, in particular at high wind velocity, are needed to better assess how projections of global climate warming in a windier world could affect the ocean carbon uptake, and alter the ocean heat budget at high latitudes. Air-sea fluxes of momentum, sensible and latent heat (water vapor) and carbon dioxide (CO2) are to be measured continuously underway on cruises using micrometeorological eddy covariance techniques adapted to ship-board use. The measured gas transfer velocity (K) is then to be related to other parameters known to affect air-sea-fluxes. A stated goal of this work is the collection of a set of direct air-sea flux measurements at high wind speeds, conditions where parameterization of the relationship of gas exchange to wind-speed remains contentious. The studies will be carried out at sites in the Southern Ocean using the USAP RV Nathaniel B Palmer as measurment platform. Co-located pCO2 data, to be used in the overall analysis and enabling internal consistency checks, are being collected from existing underway systems aboard the USAP research vessel under other NSF awards.", "east": 146.0, "geometry": "POINT(131.75 -57.2)", "instruments": "NOT APPLICABLE \u003e NOT APPLICABLE \u003e NOT APPLICABLE", "is_usap_dc": true, "keywords": "HEAT FLUX; DISSOLVED GASES; Antarctica; USAP-DC; NOT APPLICABLE", "locations": "Antarctica", "north": -47.0, "nsf_funding_programs": "Antarctic Ocean and Atmospheric Sciences", "paleo_time": null, "persons": "Miller, Scott", "platforms": "OTHER \u003e NOT APPLICABLE \u003e NOT APPLICABLE", "repo": "R2R", "repositories": "R2R; USAP-DC", "science_programs": null, "south": -67.4, "title": "Air-Sea Fluxes of Momentum, Heat, and Carbon Dioxide at High Wind Speeds in the Southern Ocean", "uid": "p0010137", "west": 117.5}, {"awards": "1935755 Lamp, Jennifer; 1935907 Balco, Gregory; 1935945 Tremblay, Marissa", "bounds_geometry": "POLYGON((160 -77.25,160.4 -77.25,160.8 -77.25,161.2 -77.25,161.6 -77.25,162 -77.25,162.4 -77.25,162.8 -77.25,163.2 -77.25,163.6 -77.25,164 -77.25,164 -77.325,164 -77.4,164 -77.475,164 -77.55,164 -77.625,164 -77.7,164 -77.775,164 -77.85,164 -77.925,164 -78,163.6 -78,163.2 -78,162.8 -78,162.4 -78,162 -78,161.6 -78,161.2 -78,160.8 -78,160.4 -78,160 -78,160 -77.925,160 -77.85,160 -77.775,160 -77.7,160 -77.625,160 -77.55,160 -77.475,160 -77.4,160 -77.325,160 -77.25))", "dataset_titles": null, "datasets": null, "date_created": "Tue, 25 Aug 2020 00:00:00 GMT", "description": ". ______________________________________________________________________________________________________________ Part I: Nontechnical Description Scientists study the Earth\u0027s past climate in order to understand how the climate will respond to ongoing global change in the future. One of the best analogs for future climate might the period that occurred approximately 3 million years ago, during an interval known as the mid-Pliocene Warm Period. During this period, the concentration of carbon dioxide in the atmosphere was similar to today\u0027s and sea level was 15 or more meters higher, due primarily to warming and consequent ice sheet melting in polar regions. However, the temperatures in polar regions during the mid-Pliocene Warm Period are not well determined, in part because we do not have records like ice cores that extend this far back in time. This project will provide constraints on surface temperatures in Antarctica during the mid-Pliocene Warm Period using a new type of climate substitute, known as cosmogenic noble gas paleothermometry. This project focuses on an area of Antarctica called the McMurdo Dry Valleys. In this area, climate models suggest that temperatures were more than 10 C warmer during the mid-Pliocene than they are today, but indirect geologic observations suggest that temperatures may have been similar to today. The McMurdo Dry Valleys are also a place where rocks have been exposed to Earth surface conditions for several million years, and where this new climate substitute can be readily applied. The team will reconstruct temperatures in the McMurdo Dry Valleys during the mid-Pliocene Warm Period in order to resolve the discrepancy between models and indirect geologic observations and provide much-needed constraints on the sensitivity of Antarctic ice sheets to warming temperatures. The temperature reconstructions generated in this project will have scientific impact in multiple disciplines, including climate science, glaciology, geomorphology, and planetary science. In addition, the project will (1) broaden the participation of underrepresented groups by supporting two early-career female principal investigators, (2) build STEM talent through the education and training of a graduate student, (3) enhance infrastructure for research via publication of a publicly-accessible, open-source code library, and (4) be broadly disseminated via social media, blog posts, publications, and conference presentations. Part II: Technical Description The mid-Pliocene Warm Period (3-3.3 million years ago) is the most recent interval of the geologic past when atmospheric CO2 concentrations exceeded 400 ppm and is widely considered an analog for how Earth\u2019s climate system will respond to current global change. Climate models predict polar amplification - the occurrence of larger changes in temperatures at high latitudes than the global average due to a radiative forcing - both during the mid-Pliocene Warm Period and due to current climate warming. However, the predicted magnitude of polar amplification is highly uncertain in both cases. The magnitude of polar amplification has important implications for the sensitivity of ice sheets to warming and the contribution of ice sheet melting to sea level change. Proxy-based constraints on polar surface air temperatures during the mid-Pliocene Warm Period are sparse to non-existent. In Antarctica, there is only indirect evidence for the magnitude of warming during this time. This project will provide constraints on surface temperatures in the McMurdo Dry Valleys of Antarctica during the mid-Pliocene Warm Period using a newly developed technique called cosmogenic noble gas (CNG) paleothermometry. CNG paleothermometry utilizes the diffusive behavior of cosmogenic 3He in quartz to quantify the temperatures rocks experience while exposed to cosmic-ray particles within a few meters of the Earth\u2019s surface. The very low erosion rates and subzero temperatures characterizing the McMurdo Dry Valleys make this region uniquely suited for the application of CNG paleothermometry for addressing the question: what temperatures characterized the McMurdo Dry Valleys during the mid-Pliocene Warm Period? To address this question, the team will collect bedrock samples at several locations in the McMurdo Dry Valleys where erosion rates are known to be low enough that cosmic ray exposure extends into the mid-Pliocene or earlier. They will pair cosmogenic 3He measurements, which will record the thermal histories of our samples, with measurements of cosmogenic 10Be, 26Al, and 21Ne, which record samples exposure and erosion histories. We will also make in situ measurements of rock and air temperatures at sample sites in order to quantify the effect of radiative heating and develop a statistical relationship between rock and air temperatures, as well as conduct diffusion experiments to quantify the kinetics of 3He diffusion specific to each sample. This suite of observations will be used to model permissible thermal histories and place constraints on temperatures during the mid-Pliocene Warm Period interval of cosmic-ray exposure. This award reflects NSF\u0027s statutory mission and has been deemed worthy of support through evaluation using the Foundation\u0027s intellectual merit and broader impacts review criteria.", "east": 164.0, "geometry": "POINT(162 -77.625)", "instruments": null, "is_usap_dc": true, "keywords": "FIELD INVESTIGATION; AMD; LABORATORY; USA/NSF; Amd/Us; ISOTOPES; Dry Valleys; AIR TEMPERATURE RECONSTRUCTION; GEOCHEMISTRY; USAP-DC", "locations": "Dry Valleys", "north": -77.25, "nsf_funding_programs": "Antarctic Earth Sciences; Antarctic Earth Sciences; Antarctic Earth Sciences", "paleo_time": null, "persons": "Tremblay, Marissa; Granger, Darryl; Balco, Gregory; Lamp, Jennifer", "platforms": "LAND-BASED PLATFORMS \u003e FIELD SITES \u003e FIELD INVESTIGATION; OTHER \u003e PHYSICAL MODELS \u003e LABORATORY", "repositories": null, "science_programs": null, "south": -78.0, "title": "Collaborative \r\nResearch: Reconstructing Temperatures during the Mid-Pliocene Warm \r\nPeriod in the McMurdo Dry Valleys with Cosmogenic Noble Gases", "uid": "p0010123", "west": 160.0}, {"awards": "1341658 Mukhopadhyay, Sujoy", "bounds_geometry": "POLYGON((-116.45 -84.786,-116.443 -84.786,-116.436 -84.786,-116.429 -84.786,-116.422 -84.786,-116.415 -84.786,-116.408 -84.786,-116.401 -84.786,-116.394 -84.786,-116.387 -84.786,-116.38 -84.786,-116.38 -84.7864,-116.38 -84.7868,-116.38 -84.7872,-116.38 -84.7876,-116.38 -84.788,-116.38 -84.7884,-116.38 -84.7888,-116.38 -84.7892,-116.38 -84.7896,-116.38 -84.79,-116.387 -84.79,-116.394 -84.79,-116.401 -84.79,-116.408 -84.79,-116.415 -84.79,-116.422 -84.79,-116.429 -84.79,-116.436 -84.79,-116.443 -84.79,-116.45 -84.79,-116.45 -84.7896,-116.45 -84.7892,-116.45 -84.7888,-116.45 -84.7884,-116.45 -84.788,-116.45 -84.7876,-116.45 -84.7872,-116.45 -84.7868,-116.45 -84.7864,-116.45 -84.786))", "dataset_titles": "Ohio Range Subglacial rock core cosmogenic nuclide data", "datasets": [{"dataset_uid": "601351", "doi": "10.15784/601351", "keywords": "Aluminum-26; Antarctica; Beryllium-10; Cosmogenic Dating; Cosmogenic Radionuclides; Glaciers/ice Sheet; Glaciers/Ice Sheet; Glaciology; Ice Sheet Fluctuations; Ohio Range; Rocks", "people": "Mukhopadhyay, Sujoy", "repository": "USAP-DC", "science_program": null, "title": "Ohio Range Subglacial rock core cosmogenic nuclide data", "url": "https://www.usap-dc.org/view/dataset/601351"}], "date_created": "Sun, 28 Jun 2020 00:00:00 GMT", "description": "Modeling fluctuations in the extent of the West Antarctic Ice Sheet (WAIS) over time is a principal goal of the glaciological community. These models will provide a critical basis for predictions of future sea level change, and therefore this work great societal relevance. The mid-Pliocene time interval is of particular interest, as it is the most recent period in which global temperatures were warmer and atmospheric CO2 concentrations may have been higher than current levels. However, observational constraints on fluctuations in the WAIS older than the last glacial maximum are rare. The investigators propose to collect geochemical data from the Ohio Range and Scott Glacier to quantify past variability in the height of the WAIS. Limited available cosmogenic nuclide data are broadly consistent with a model indicating that Pliocene WAIS elevations and volumes were smaller than at present, and that WAIS collapse was common. The PIs will use geologic observations and cosmogenic nuclide concentrations from bedrock samples at multiple locations and at multiple elevations, including sub-ice samples, to constrain WAIS ice volume changes in a \"dipstick\" like fashion. Data obtained from the proposed research will provide targets for data-ice sheet model comparisons to accurately characterize Plio-Pleistocene and future WAIS behavior. As part of this project, the investigators will work with the Natural History Museum and the Earth \u0026 Planetary Science department at Harvard to develop an exhibit that will become part of the Museum\u0027s recently opened Earth and Planetary Science Gallery. The project involves mentoring of a female graduate student as well as an undergraduate student.", "east": -116.38, "geometry": "POINT(-116.415 -84.788)", "instruments": "IN SITU/LABORATORY INSTRUMENTS \u003e CORERS \u003e ROCK CORERS; IN SITU/LABORATORY INSTRUMENTS \u003e SPECTROMETERS/RADIOMETERS \u003e AMS; IN SITU/LABORATORY INSTRUMENTS \u003e CHEMICAL METERS/ANALYZERS \u003e GAS CHROMATOGRAPHS", "is_usap_dc": true, "keywords": "Ice Sheet Fluctuations; ALUMINUM-26 ANALYSIS; BERYLLIUM-10 ANALYSIS; Cosmogenic Radionuclides; USAP-DC; FIELD INVESTIGATION; AMD; Ohio Range; GLACIER THICKNESS/ICE SHEET THICKNESS; ICE SHEETS; LABORATORY", "locations": "Ohio Range", "north": -84.786, "nsf_funding_programs": "Antarctic Earth Sciences", "paleo_time": null, "persons": "Mukhopadhyay, Sujoy", "platforms": "LAND-BASED PLATFORMS \u003e FIELD SITES \u003e FIELD INVESTIGATION; OTHER \u003e PHYSICAL MODELS \u003e LABORATORY", "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -84.79, "title": "Constraining Plio-Pleistocene West Antarctic Ice Sheet Behavior from the Ohio Range and Scott Glacier", "uid": "p0010113", "west": -116.45}, {"awards": "1341432 Brzezinski, Mark; 1341464 Robinson, Rebecca", "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": "601522", "doi": "10.15784/601522", "keywords": "Antarctica; Nitrogen Isotopes; Oceans; Paleoproxies; Southern Ocean", "people": "Jones, Colin; Riesselman, Christina; Robinson, Rebecca; Closset, Ivia; Kelly, Roger; Robinson, Rebecca ; Brzezinski, Mark", "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": "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": "Jones, Colin; Robinson, Rebecca; Riesselman, Christina; 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"}, {"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": "Jones, Janice L.; Closset, Ivia; 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": "601276", "doi": "10.15784/601276", "keywords": "Antarctica; Biogenic Silica; Nitrogen Isotopes; Southern Ocean", "people": "Robinson, Rebecca; Brzezinski, Mark", "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": "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": "601269", "doi": "10.15784/601269", "keywords": "Antarctica; Chlorophyll; Southern Ocean", "people": "Robinson, Rebecca; Brzezinski, Mark", "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": "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": "Robinson, Rebecca; Brzezinski, Mark; Jones, Janice L.; Closset, Ivia", "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"}], "date_created": "Wed, 26 Feb 2020 00:00:00 GMT", "description": "Collaborative Proposal: A field and laboratory examination of the diatom N and Si isotope proxies: Implications for assessing the Southern Ocean biological pump 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. This 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": "1443263 Higgins, John; 1443306 Mayewski, Paul", "bounds_geometry": null, "dataset_titles": "Allan Hills ice water stable isotope record for dD, d18O; Carbon dioxide concentration and its stable carbon isotope composition in Allan Hills ice cores; Elemental and isotopic composition of heavy noble gases in Allan Hills ice cores; Elemental and isotopic composition of nitrogen, oxygen, and argon in Allan Hills ice cores; Greenhouse gas composition in the Allan Hills S27 ice core; Methane concentration in Allan Hills ice cores; Stable isotope composition of the trapped air in the Allan Hills S27 ice core; Stable water isotope data for the AH-1502 ice core drilled at the Allan Hills Blue ice area; Stable water isotope data for the AH-1503 ice core drilled at the Allan Hills Blue ice area; Stable water isotope data for the surface samples collected at the Allan Hills Blue ice area", "datasets": [{"dataset_uid": "601203", "doi": "10.15784/601203", "keywords": "Allan Hills; Allan Hills Project; Antarctica; Chemistry:ice; Chemistry:Ice; Gas Chromatography; Glaciers/ice Sheet; Glaciers/Ice Sheet; Glaciology; Greenhouse Gas; Ice; Ice Core Data; Ice Core Gas Records; Methane; Snow/ice; Snow/Ice", "people": "Bender, Michael; Brook, Edward J.; Yan, Yuzhen; Higgins, John", "repository": "USAP-DC", "science_program": "Allan Hills", "title": "Methane concentration in Allan Hills ice cores", "url": "https://www.usap-dc.org/view/dataset/601203"}, {"dataset_uid": "601201", "doi": "10.15784/601201", "keywords": "Allan Hills; Allan Hills Project; Antarctica; Argon; Chemistry:ice; Chemistry:Ice; Glaciers/ice Sheet; Glaciers/Ice Sheet; Glaciology; Ice Core; Ice Core Data; Ice Core Gas Records; Krypton; Mass Spectrometer; Noble Gas; Snow/ice; Snow/Ice; Xenon", "people": "Yan, Yuzhen; Ng, Jessica; Higgins, John; Severinghaus, Jeffrey P.; Bender, Michael", "repository": "USAP-DC", "science_program": "Allan Hills", "title": "Elemental and isotopic composition of heavy noble gases in Allan Hills ice cores", "url": "https://www.usap-dc.org/view/dataset/601201"}, {"dataset_uid": "601128", "doi": "10.15784/601128", "keywords": "Allan Hills; Antarctica; Blue Ice; Chemistry:ice; Chemistry:Ice; Delta 18O; Glaciers/ice Sheet; Glaciers/Ice Sheet; Glaciology; Ice Core Records; Isotope Record; Mass Spectrometry; Stable Water Isotopes", "people": "Kurbatov, Andrei V.; Mayewski, Paul A.; Introne, Douglas; Yan, Yuzhen", "repository": "USAP-DC", "science_program": "Allan Hills", "title": "Stable water isotope data for the AH-1503 ice core drilled at the Allan Hills Blue ice area", "url": "https://www.usap-dc.org/view/dataset/601128"}, {"dataset_uid": "601129", "doi": "10.15784/601129", "keywords": "Allan Hills; Allan Hills Project; Antarctica; Blue Ice; Delta 18O; Glaciers/ice Sheet; Glaciers/Ice Sheet; Glaciology; Ice Core; Ice Core Chemistry; Ice Core Records; Isotope Data; Oxygen; Snow/ice; Snow/Ice; Stable Water Isotopes; Transantarctic Mountains", "people": "Kurbatov, Andrei V.; Mayewski, Paul A.; Introne, Douglas; Yan, Yuzhen", "repository": "USAP-DC", "science_program": "Allan Hills", "title": "Stable water isotope data for the AH-1502 ice core drilled at the Allan Hills Blue ice area", "url": "https://www.usap-dc.org/view/dataset/601129"}, {"dataset_uid": "601130", "doi": "10.15784/601130", "keywords": "Allan Hills; Allan Hills Project; Antarctica; Blue Ice; Chemistry:ice; Chemistry:Ice; Delta 18O; Delta Deuterium; Glaciers/ice Sheet; Glaciers/Ice Sheet; Glaciology; Ice Core Gas Records; Ice Core Records; Oxygen; Snow/ice; Snow/Ice; Stable Water Isotopes; Transantarctic Mountains", "people": "Introne, Douglas; Kurbatov, Andrei V.; Mayewski, Paul A.; Yan, Yuzhen", "repository": "USAP-DC", "science_program": "Allan Hills", "title": "Stable water isotope data for the surface samples collected at the Allan Hills Blue ice area", "url": "https://www.usap-dc.org/view/dataset/601130"}, {"dataset_uid": "601483", "doi": "10.15784/601483", "keywords": "Allan Hills; Antarctica; Argon; Ice; Ice Core Data; Ice Core Gas Records; Isotope; Mass Spectrometry; Nitrogen; Oxygen", "people": "Higgins, John; Bender, Michael; Yan, Yuzhen", "repository": "USAP-DC", "science_program": "Allan Hills", "title": "Elemental and isotopic composition of nitrogen, oxygen, and argon in Allan Hills ice cores", "url": "https://www.usap-dc.org/view/dataset/601483"}, {"dataset_uid": "601863", "doi": null, "keywords": "Allan Hills; Antarctica; Cryosphere; Isotope Data", "people": "Higgins, John; Severinghaus, Jeffrey P.; Introne, Douglas; Mayewski, Paul A.; Brook, Edward; Kurbatov, Andrei V.", "repository": "USAP-DC", "science_program": "COLDEX", "title": "Allan Hills ice water stable isotope record for dD, d18O", "url": "https://www.usap-dc.org/view/dataset/601863"}, {"dataset_uid": "601863", "doi": null, "keywords": "Allan Hills; Antarctica; Cryosphere; Isotope Data", "people": "Kurbatov, Andrei V.; Mayewski, Paul A.; Brook, Edward; Introne, Douglas; Higgins, John; Severinghaus, Jeffrey P.", "repository": "USAP-DC", "science_program": "Allan Hills", "title": "Allan Hills ice water stable isotope record for dD, d18O", "url": "https://www.usap-dc.org/view/dataset/601863"}, {"dataset_uid": "601512", "doi": "10.15784/601512", "keywords": "Allan Hills; Antarctica; Blue Ice; Ice Core; Ice Core Gas Records; Isotope; Nitrogen; Oxygen", "people": "Yan, Yuzhen; Higgins, John; Bender, Michael", "repository": "USAP-DC", "science_program": "Allan Hills", "title": "Stable isotope composition of the trapped air in the Allan Hills S27 ice core", "url": "https://www.usap-dc.org/view/dataset/601512"}, {"dataset_uid": "601425", "doi": "10.15784/601425", "keywords": "Allan Hills; Antarctica; Blue Ice; Carbon Dioxide; Ice Core; Methane", "people": "Brook, Edward J.; Yan, Yuzhen", "repository": "USAP-DC", "science_program": "Allan Hills", "title": "Greenhouse gas composition in the Allan Hills S27 ice core", "url": "https://www.usap-dc.org/view/dataset/601425"}, {"dataset_uid": "601202", "doi": "10.15784/601202", "keywords": "Allan Hills; Allan Hills Project; Antarctica; Carbon Dioxide; Carbon Isotopes; Chemistry:ice; Chemistry:Ice; CO2; Gas Chromatography; Glaciers/ice Sheet; Glaciers/Ice Sheet; Glaciology; Ice; Ice Core Data; Ice Core Gas Records; Ice Core Records; Mass Spectrometer; Mass Spectrometry; Methane; Snow/ice; Snow/Ice", "people": "Brook, Edward J.; Bender, Michael; Yan, Yuzhen; Higgins, John", "repository": "USAP-DC", "science_program": "Allan Hills", "title": "Carbon dioxide concentration and its stable carbon isotope composition in Allan Hills ice cores", "url": "https://www.usap-dc.org/view/dataset/601202"}], "date_created": "Thu, 18 Oct 2018 00:00:00 GMT", "description": "Bubbles of ancient air trapped in ice cores permit the direct reconstruction of atmospheric composition and allow us to link greenhouse gases and global climate over the last 800,000 years. Previous field expeditions to the Allan Hills blue ice area, Antarctica, have recovered ice cores that date to one million years, the oldest ice cores yet recovered from Antarctica. These records have revealed that interglacial CO2 concentrations decreased by 800,000 years ago and that, in the warmer world 1 million years ago, CO2 and Antarctic temperature were linked as during the last 800,000 years. This project will return to the Allan Hills blue ice area to recover additional ice cores that date to 1 million years or older. The climate records developed from the drilled ice cores will provide new insights into the chemical composition of the atmosphere and Antarctic climate during times of comparable or even greater warmth than the present day. Our results will help answer questions about issues associated with anthropogenic change. These include the relationship between temperature change and the mass balance of Antarctic ice; precipitation and aridity variations associated with radiatively forced climate change; and the climate significance of sea ice extent. The project will entrain two graduate students and a postdoctoral scholar, and will conduct outreach including workshops to engage teachers in carbon science and ice cores. Between about 2.8-0.9 million years ago, Earth\u0027s climate was characterized by 40,000-year cycles, driven or paced by changes in the tilt of Earth\u0027s spin axis. Much is known about the \"40,000-year\" world from studies of deep-sea sediments, but our understanding of climate change during this period is incomplete because we lack records of Antarctic climate and direct records of atmospheric greenhouse gas concentrations. We propose to address these issues by building on our recent studies of ancient ice from the Main Ice Field, Allan Hills, Antarctica. During previous field seasons we recovered ice extending, discontinuously, from 0.1-1.0 million years old. Ice was dated by measuring the 40Ar/38Ar (Argon) ratio of the trapped gases. Our discovery of million year-old ice demonstrates that there is gas-record-quality ice from the 40,000-year world in the Allan Hills Main Ice Field. We have identified two different sites, each overlying bedrock at ~ 200 m depth, that are attractive targets for coring ice dating to 1 million years and older. This project aims to core the ice at these two sites, re-occupy a previous site with million year-old ice and drill it down to the bedrock, and generate 10-20 short (~10-meter) cores in areas where our previous work and terrestrial meteorite ages suggest ancient surface ice. We plan to date the ice using the 40Ar/38Ar ages of trapped Argon. We also plan to characterize the continuity of our cores by measuring the deuterium and oxygen isotope ratios in the ice, methane, ratios of Oxygen and Argon to Nitrogen in trapped gas, the Nitrogen-15 isotope (d15N) of Nitrogen, and the Oxygen-18 isotope (d18O) of Oxygen. As the ice may be stratigraphically disturbed, these measurements will provide diagnostic properties for assessing the continuity of the ice-core records. Successful retrieval of ice older than one million years will provide the opportunity for follow-up work to measure the CO2 concentration and other properties within the ice to inform on the temperature history of the Allan Hills region, dust sources and source-area aridity, moisture sources, densification conditions, global average ocean temperature, and greenhouse gas concentrations. We will analyze the data in the context of leading hypotheses of the 40,000-year world and the Mid-Pleistocene Transition to the 100,000-year world. We expect to advance understanding of climate dynamics during these periods.", "east": null, "geometry": null, "instruments": "IN SITU/LABORATORY INSTRUMENTS \u003e CORERS \u003e CORING DEVICES", "is_usap_dc": true, "keywords": "Amd/Us; AMD; Allan Hills; USA/NSF; FIELD INVESTIGATION; USAP-DC; Ice Core; LABORATORY", "locations": "Allan Hills", "north": null, "nsf_funding_programs": "Antarctic Glaciology; Antarctic Glaciology", "paleo_time": null, "persons": "Mayewski, Paul A.; Kurbatov, Andrei V.; Higgins, John; Bender, Michael", "platforms": "LAND-BASED PLATFORMS \u003e FIELD SITES \u003e FIELD INVESTIGATION; OTHER \u003e PHYSICAL MODELS \u003e LABORATORY", "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": "Allan Hills", "south": null, "title": "Collaborative Research: Window into the World with 40,000-year Glacial Cycles from Climate Records in Million Year-old Ice from the Allan Hills Blue Ice Area", "uid": "p0000760", "west": null}, {"awards": "0944764 Brook, Edward J.", "bounds_geometry": null, "dataset_titles": "Abrupt Change in Atmospheric CO2 During the Last Ice Age; High-resolution Atmospheric CO2 during 7.4-9.0 ka", "datasets": [{"dataset_uid": "609527", "doi": "10.7265/N5QF8QT5", "keywords": "Antarctica; Chemistry:fluid; Chemistry:Fluid; Geochemistry; Geochronology; Glaciers/ice Sheet; Glaciers/Ice Sheet; Glaciology; Ice Core Records; Paleoclimate; Siple Dome; Siple Dome Ice Core; South Pole; WAISCORES", "people": "Ahn, Jinho; Brook, Edward J.", "repository": "USAP-DC", "science_program": "Siple Dome Ice Core", "title": "High-resolution Atmospheric CO2 during 7.4-9.0 ka", "url": "https://www.usap-dc.org/view/dataset/609527"}, {"dataset_uid": "609539", "doi": "10.7265/N5F47M23", "keywords": "Antarctica; Arctic; Byrd; Chemistry:fluid; Chemistry:Fluid; CO2; Geochemistry; GISP2; Glaciers/ice Sheet; Glaciers/Ice Sheet; Glaciology; Ice Core Records; Methane; Paleoclimate; Siple Dome Ice Core; Taylor Dome; Taylor Dome Ice Core", "people": "Brook, Edward J.; Ahn, Jinho", "repository": "USAP-DC", "science_program": "Byrd Ice Core", "title": "Abrupt Change in Atmospheric CO2 During the Last Ice Age", "url": "https://www.usap-dc.org/view/dataset/609539"}, {"dataset_uid": "609539", "doi": "10.7265/N5F47M23", "keywords": "Antarctica; Arctic; Byrd; Chemistry:fluid; Chemistry:Fluid; CO2; Geochemistry; GISP2; Glaciers/ice Sheet; Glaciers/Ice Sheet; Glaciology; Ice Core Records; Methane; Paleoclimate; Siple Dome Ice Core; Taylor Dome; Taylor Dome Ice Core", "people": "Brook, Edward J.; Ahn, Jinho", "repository": "USAP-DC", "science_program": "Siple Dome Ice Core", "title": "Abrupt Change in Atmospheric CO2 During the Last Ice Age", "url": "https://www.usap-dc.org/view/dataset/609539"}, {"dataset_uid": "609539", "doi": "10.7265/N5F47M23", "keywords": "Antarctica; Arctic; Byrd; Chemistry:fluid; Chemistry:Fluid; CO2; Geochemistry; GISP2; Glaciers/ice Sheet; Glaciers/Ice Sheet; Glaciology; Ice Core Records; Methane; Paleoclimate; Siple Dome Ice Core; Taylor Dome; Taylor Dome Ice Core", "people": "Ahn, Jinho; Brook, Edward J.", "repository": "USAP-DC", "science_program": "Taylor Dome Ice Core", "title": "Abrupt Change in Atmospheric CO2 During the Last Ice Age", "url": "https://www.usap-dc.org/view/dataset/609539"}], "date_created": "Thu, 08 Aug 2013 00:00:00 GMT", "description": "This award supports a project to create new, unprecedented high-resolution atmospheric carbon dioxide (CO2) records spanning intervals of abrupt climate changes during the last glacial period and the early Holocene. The proposed work will utilize high-precision methods on existing ice cores from high accumulation sites such as Siple Dome and Byrd Station, Antarctica and will improve our understanding of how fast CO2 can change naturally, how its variations are linked with climate, and, combined with a coupled climate-carbon cycle model, will clarify the role of terrestrial and oceanic processes during past abrupt changes of climate and CO2. The intellectual merit of this work is that CO2 is the most important anthropogenic greenhouse gas and understanding its past variations, its sources and sinks, and how they are linked to climate change is a major goal of the climate research community. This project will produce high quality data on centennial to multi-decadal time scales. Such high-resolution work has not been conducted before because of insufficient analytical precision, slow experimental procedures in previous studies, or lack of available samples. The proposed research will complement future high-resolution studies from WAIS Divide ice cores and will provide ice core CO2 records for the target age intervals, which are in the zone of clathrate formation in the WAIS ice cores. Clathrate hydrate is a phase composed of air and ice. CO2 analyses have historically been less precise in clathrate ice than in ?bubbly ice? such as the Siple Dome ice core that will be analyzed in the proposed project. High quality, high-resolution results from specific intervals in Siple Dome that we propose to analyze will provide important data for verifying the WAIS Divide record. The broader impacts of the work are that current models show a large uncertainty of future climate-carbon cycle interactions. The results of this proposed work will be used for testing coupled carbon cycle-climate models and may contribute to reducing this uncertainty. The project will contribute to the training of several undergraduate students and a full-time technician. Both will learn analytical techniques and the basic science involved. Minorities and female students will be highly encouraged to participate in this project. Outreach efforts will include participation in news media interviews, at a local festival celebrating art, science and technology, and giving seminar presentations in the US and foreign countries. The OSU ice core laboratory has begun a collaboration with a regional science museum and is developing ideas to build an exhibition booth to make public be aware of climate change and ice core research. All data will be archived at the National Snow and Ice Data Center and at other similar archives per the OPP data policy.", "east": null, "geometry": null, "instruments": "IN SITU/LABORATORY INSTRUMENTS \u003e CHEMICAL METERS/ANALYZERS \u003e CO2 ANALYZERS; IN SITU/LABORATORY INSTRUMENTS \u003e CHEMICAL METERS/ANALYZERS \u003e GAS CHROMATOGRAPHS; IN SITU/LABORATORY INSTRUMENTS \u003e CHEMICAL METERS/ANALYZERS \u003e GAS CHROMATOGRAPHS", "is_usap_dc": true, "keywords": "GROUND-BASED OBSERVATIONS; CO2 Concentrations; Ice Core Gas Age; CO2 Uncertainty; LABORATORY; Ice Core Depth; Not provided; CH4 Concentrations", "locations": null, "north": null, "nsf_funding_programs": "Antarctic Glaciology", "paleo_time": "NOT APPLICABLE; NOT APPLICABLE", "persons": "Ahn, Jinho; Brook, Edward J.", "platforms": "LAND-BASED PLATFORMS \u003e PERMANENT LAND SITES \u003e GROUND-BASED OBSERVATIONS; Not provided; OTHER \u003e PHYSICAL MODELS \u003e LABORATORY", "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": null, "title": "Atmospheric CO2 and Abrupt Climate Change", "uid": "p0000179", "west": null}, {"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}]
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Project Title/Abstract/Map | NSF Award(s) | Date Created | PIs / Scientists | Dataset Links and Repositories | Abstract | Bounds Geometry | Geometry | Selected | Visible | |||
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Air-Sea Fluxes of Momentum, Heat, and Carbon Dioxide at High Wind Speeds in the Southern Ocean
|
1043623 |
2020-10-09 | Miller, Scott | Accurate parameterizations of the air-sea fluxes of CO2 into the Southern Ocean, in particular at high wind velocity, are needed to better assess how projections of global climate warming in a windier world could affect the ocean carbon uptake, and alter the ocean heat budget at high latitudes. Air-sea fluxes of momentum, sensible and latent heat (water vapor) and carbon dioxide (CO2) are to be measured continuously underway on cruises using micrometeorological eddy covariance techniques adapted to ship-board use. The measured gas transfer velocity (K) is then to be related to other parameters known to affect air-sea-fluxes. A stated goal of this work is the collection of a set of direct air-sea flux measurements at high wind speeds, conditions where parameterization of the relationship of gas exchange to wind-speed remains contentious. The studies will be carried out at sites in the Southern Ocean using the USAP RV Nathaniel B Palmer as measurment platform. Co-located pCO2 data, to be used in the overall analysis and enabling internal consistency checks, are being collected from existing underway systems aboard the USAP research vessel under other NSF awards. | POLYGON((117.5 -47,120.35 -47,123.2 -47,126.05 -47,128.9 -47,131.75 -47,134.6 -47,137.45 -47,140.3 -47,143.15 -47,146 -47,146 -49.04,146 -51.08,146 -53.12,146 -55.16,146 -57.2,146 -59.24,146 -61.28,146 -63.32,146 -65.36,146 -67.4,143.15 -67.4,140.3 -67.4,137.45 -67.4,134.6 -67.4,131.75 -67.4,128.9 -67.4,126.05 -67.4,123.2 -67.4,120.35 -67.4,117.5 -67.4,117.5 -65.36,117.5 -63.32,117.5 -61.28,117.5 -59.24,117.5 -57.2,117.5 -55.16,117.5 -53.12,117.5 -51.08,117.5 -49.04,117.5 -47)) | POINT(131.75 -57.2) | false | false | ||||
Collaborative
Research: Reconstructing Temperatures during the Mid-Pliocene Warm
Period in the McMurdo Dry Valleys with Cosmogenic Noble Gases
|
1935755 1935907 1935945 |
2020-08-25 | Tremblay, Marissa; Granger, Darryl; Balco, Gregory; Lamp, Jennifer | No dataset link provided | . ______________________________________________________________________________________________________________ Part I: Nontechnical Description Scientists study the Earth's past climate in order to understand how the climate will respond to ongoing global change in the future. One of the best analogs for future climate might the period that occurred approximately 3 million years ago, during an interval known as the mid-Pliocene Warm Period. During this period, the concentration of carbon dioxide in the atmosphere was similar to today's and sea level was 15 or more meters higher, due primarily to warming and consequent ice sheet melting in polar regions. However, the temperatures in polar regions during the mid-Pliocene Warm Period are not well determined, in part because we do not have records like ice cores that extend this far back in time. This project will provide constraints on surface temperatures in Antarctica during the mid-Pliocene Warm Period using a new type of climate substitute, known as cosmogenic noble gas paleothermometry. This project focuses on an area of Antarctica called the McMurdo Dry Valleys. In this area, climate models suggest that temperatures were more than 10 C warmer during the mid-Pliocene than they are today, but indirect geologic observations suggest that temperatures may have been similar to today. The McMurdo Dry Valleys are also a place where rocks have been exposed to Earth surface conditions for several million years, and where this new climate substitute can be readily applied. The team will reconstruct temperatures in the McMurdo Dry Valleys during the mid-Pliocene Warm Period in order to resolve the discrepancy between models and indirect geologic observations and provide much-needed constraints on the sensitivity of Antarctic ice sheets to warming temperatures. The temperature reconstructions generated in this project will have scientific impact in multiple disciplines, including climate science, glaciology, geomorphology, and planetary science. In addition, the project will (1) broaden the participation of underrepresented groups by supporting two early-career female principal investigators, (2) build STEM talent through the education and training of a graduate student, (3) enhance infrastructure for research via publication of a publicly-accessible, open-source code library, and (4) be broadly disseminated via social media, blog posts, publications, and conference presentations. Part II: Technical Description The mid-Pliocene Warm Period (3-3.3 million years ago) is the most recent interval of the geologic past when atmospheric CO2 concentrations exceeded 400 ppm and is widely considered an analog for how Earth’s climate system will respond to current global change. Climate models predict polar amplification - the occurrence of larger changes in temperatures at high latitudes than the global average due to a radiative forcing - both during the mid-Pliocene Warm Period and due to current climate warming. However, the predicted magnitude of polar amplification is highly uncertain in both cases. The magnitude of polar amplification has important implications for the sensitivity of ice sheets to warming and the contribution of ice sheet melting to sea level change. Proxy-based constraints on polar surface air temperatures during the mid-Pliocene Warm Period are sparse to non-existent. In Antarctica, there is only indirect evidence for the magnitude of warming during this time. This project will provide constraints on surface temperatures in the McMurdo Dry Valleys of Antarctica during the mid-Pliocene Warm Period using a newly developed technique called cosmogenic noble gas (CNG) paleothermometry. CNG paleothermometry utilizes the diffusive behavior of cosmogenic 3He in quartz to quantify the temperatures rocks experience while exposed to cosmic-ray particles within a few meters of the Earth’s surface. The very low erosion rates and subzero temperatures characterizing the McMurdo Dry Valleys make this region uniquely suited for the application of CNG paleothermometry for addressing the question: what temperatures characterized the McMurdo Dry Valleys during the mid-Pliocene Warm Period? To address this question, the team will collect bedrock samples at several locations in the McMurdo Dry Valleys where erosion rates are known to be low enough that cosmic ray exposure extends into the mid-Pliocene or earlier. They will pair cosmogenic 3He measurements, which will record the thermal histories of our samples, with measurements of cosmogenic 10Be, 26Al, and 21Ne, which record samples exposure and erosion histories. We will also make in situ measurements of rock and air temperatures at sample sites in order to quantify the effect of radiative heating and develop a statistical relationship between rock and air temperatures, as well as conduct diffusion experiments to quantify the kinetics of 3He diffusion specific to each sample. This suite of observations will be used to model permissible thermal histories and place constraints on temperatures during the mid-Pliocene Warm Period interval of cosmic-ray exposure. 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. | POLYGON((160 -77.25,160.4 -77.25,160.8 -77.25,161.2 -77.25,161.6 -77.25,162 -77.25,162.4 -77.25,162.8 -77.25,163.2 -77.25,163.6 -77.25,164 -77.25,164 -77.325,164 -77.4,164 -77.475,164 -77.55,164 -77.625,164 -77.7,164 -77.775,164 -77.85,164 -77.925,164 -78,163.6 -78,163.2 -78,162.8 -78,162.4 -78,162 -78,161.6 -78,161.2 -78,160.8 -78,160.4 -78,160 -78,160 -77.925,160 -77.85,160 -77.775,160 -77.7,160 -77.625,160 -77.55,160 -77.475,160 -77.4,160 -77.325,160 -77.25)) | POINT(162 -77.625) | false | false | |||
Constraining Plio-Pleistocene West Antarctic Ice Sheet Behavior from the Ohio Range and Scott Glacier
|
1341658 |
2020-06-28 | Mukhopadhyay, Sujoy |
|
Modeling fluctuations in the extent of the West Antarctic Ice Sheet (WAIS) over time is a principal goal of the glaciological community. These models will provide a critical basis for predictions of future sea level change, and therefore this work great societal relevance. The mid-Pliocene time interval is of particular interest, as it is the most recent period in which global temperatures were warmer and atmospheric CO2 concentrations may have been higher than current levels. However, observational constraints on fluctuations in the WAIS older than the last glacial maximum are rare. The investigators propose to collect geochemical data from the Ohio Range and Scott Glacier to quantify past variability in the height of the WAIS. Limited available cosmogenic nuclide data are broadly consistent with a model indicating that Pliocene WAIS elevations and volumes were smaller than at present, and that WAIS collapse was common. The PIs will use geologic observations and cosmogenic nuclide concentrations from bedrock samples at multiple locations and at multiple elevations, including sub-ice samples, to constrain WAIS ice volume changes in a "dipstick" like fashion. Data obtained from the proposed research will provide targets for data-ice sheet model comparisons to accurately characterize Plio-Pleistocene and future WAIS behavior. As part of this project, the investigators will work with the Natural History Museum and the Earth & Planetary Science department at Harvard to develop an exhibit that will become part of the Museum's recently opened Earth and Planetary Science Gallery. The project involves mentoring of a female graduate student as well as an undergraduate student. | POLYGON((-116.45 -84.786,-116.443 -84.786,-116.436 -84.786,-116.429 -84.786,-116.422 -84.786,-116.415 -84.786,-116.408 -84.786,-116.401 -84.786,-116.394 -84.786,-116.387 -84.786,-116.38 -84.786,-116.38 -84.7864,-116.38 -84.7868,-116.38 -84.7872,-116.38 -84.7876,-116.38 -84.788,-116.38 -84.7884,-116.38 -84.7888,-116.38 -84.7892,-116.38 -84.7896,-116.38 -84.79,-116.387 -84.79,-116.394 -84.79,-116.401 -84.79,-116.408 -84.79,-116.415 -84.79,-116.422 -84.79,-116.429 -84.79,-116.436 -84.79,-116.443 -84.79,-116.45 -84.79,-116.45 -84.7896,-116.45 -84.7892,-116.45 -84.7888,-116.45 -84.7884,-116.45 -84.788,-116.45 -84.7876,-116.45 -84.7872,-116.45 -84.7868,-116.45 -84.7864,-116.45 -84.786)) | POINT(-116.415 -84.788) | false | false | |||
Collaborative Proposal: A Field and Laboratory Examination of the Diatom N and Si Isotope Proxies: Implications for Assessing the Southern Ocean Biological Pump
|
1341432 1341464 |
2020-02-26 | Robinson, Rebecca; Brzezinski, Mark | Collaborative Proposal: A field and laboratory examination of the diatom N and Si isotope proxies: Implications for assessing the Southern Ocean biological pump 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. This 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°W, 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. | 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)) | POINT(-170 -60.5) | false | false | ||||
Collaborative Research: Window into the World with 40,000-year Glacial Cycles from Climate Records in Million Year-old Ice from the Allan Hills Blue Ice Area
|
1443263 1443306 |
2018-10-18 | Mayewski, Paul A.; Kurbatov, Andrei V.; Higgins, John; Bender, Michael | Bubbles of ancient air trapped in ice cores permit the direct reconstruction of atmospheric composition and allow us to link greenhouse gases and global climate over the last 800,000 years. Previous field expeditions to the Allan Hills blue ice area, Antarctica, have recovered ice cores that date to one million years, the oldest ice cores yet recovered from Antarctica. These records have revealed that interglacial CO2 concentrations decreased by 800,000 years ago and that, in the warmer world 1 million years ago, CO2 and Antarctic temperature were linked as during the last 800,000 years. This project will return to the Allan Hills blue ice area to recover additional ice cores that date to 1 million years or older. The climate records developed from the drilled ice cores will provide new insights into the chemical composition of the atmosphere and Antarctic climate during times of comparable or even greater warmth than the present day. Our results will help answer questions about issues associated with anthropogenic change. These include the relationship between temperature change and the mass balance of Antarctic ice; precipitation and aridity variations associated with radiatively forced climate change; and the climate significance of sea ice extent. The project will entrain two graduate students and a postdoctoral scholar, and will conduct outreach including workshops to engage teachers in carbon science and ice cores. Between about 2.8-0.9 million years ago, Earth's climate was characterized by 40,000-year cycles, driven or paced by changes in the tilt of Earth's spin axis. Much is known about the "40,000-year" world from studies of deep-sea sediments, but our understanding of climate change during this period is incomplete because we lack records of Antarctic climate and direct records of atmospheric greenhouse gas concentrations. We propose to address these issues by building on our recent studies of ancient ice from the Main Ice Field, Allan Hills, Antarctica. During previous field seasons we recovered ice extending, discontinuously, from 0.1-1.0 million years old. Ice was dated by measuring the 40Ar/38Ar (Argon) ratio of the trapped gases. Our discovery of million year-old ice demonstrates that there is gas-record-quality ice from the 40,000-year world in the Allan Hills Main Ice Field. We have identified two different sites, each overlying bedrock at ~ 200 m depth, that are attractive targets for coring ice dating to 1 million years and older. This project aims to core the ice at these two sites, re-occupy a previous site with million year-old ice and drill it down to the bedrock, and generate 10-20 short (~10-meter) cores in areas where our previous work and terrestrial meteorite ages suggest ancient surface ice. We plan to date the ice using the 40Ar/38Ar ages of trapped Argon. We also plan to characterize the continuity of our cores by measuring the deuterium and oxygen isotope ratios in the ice, methane, ratios of Oxygen and Argon to Nitrogen in trapped gas, the Nitrogen-15 isotope (d15N) of Nitrogen, and the Oxygen-18 isotope (d18O) of Oxygen. As the ice may be stratigraphically disturbed, these measurements will provide diagnostic properties for assessing the continuity of the ice-core records. Successful retrieval of ice older than one million years will provide the opportunity for follow-up work to measure the CO2 concentration and other properties within the ice to inform on the temperature history of the Allan Hills region, dust sources and source-area aridity, moisture sources, densification conditions, global average ocean temperature, and greenhouse gas concentrations. We will analyze the data in the context of leading hypotheses of the 40,000-year world and the Mid-Pleistocene Transition to the 100,000-year world. We expect to advance understanding of climate dynamics during these periods. | None | None | false | false | ||||
Atmospheric CO2 and Abrupt Climate Change
|
0944764 |
2013-08-08 | Ahn, Jinho; Brook, Edward J. | This award supports a project to create new, unprecedented high-resolution atmospheric carbon dioxide (CO2) records spanning intervals of abrupt climate changes during the last glacial period and the early Holocene. The proposed work will utilize high-precision methods on existing ice cores from high accumulation sites such as Siple Dome and Byrd Station, Antarctica and will improve our understanding of how fast CO2 can change naturally, how its variations are linked with climate, and, combined with a coupled climate-carbon cycle model, will clarify the role of terrestrial and oceanic processes during past abrupt changes of climate and CO2. The intellectual merit of this work is that CO2 is the most important anthropogenic greenhouse gas and understanding its past variations, its sources and sinks, and how they are linked to climate change is a major goal of the climate research community. This project will produce high quality data on centennial to multi-decadal time scales. Such high-resolution work has not been conducted before because of insufficient analytical precision, slow experimental procedures in previous studies, or lack of available samples. The proposed research will complement future high-resolution studies from WAIS Divide ice cores and will provide ice core CO2 records for the target age intervals, which are in the zone of clathrate formation in the WAIS ice cores. Clathrate hydrate is a phase composed of air and ice. CO2 analyses have historically been less precise in clathrate ice than in ?bubbly ice? such as the Siple Dome ice core that will be analyzed in the proposed project. High quality, high-resolution results from specific intervals in Siple Dome that we propose to analyze will provide important data for verifying the WAIS Divide record. The broader impacts of the work are that current models show a large uncertainty of future climate-carbon cycle interactions. The results of this proposed work will be used for testing coupled carbon cycle-climate models and may contribute to reducing this uncertainty. The project will contribute to the training of several undergraduate students and a full-time technician. Both will learn analytical techniques and the basic science involved. Minorities and female students will be highly encouraged to participate in this project. Outreach efforts will include participation in news media interviews, at a local festival celebrating art, science and technology, and giving seminar presentations in the US and foreign countries. The OSU ice core laboratory has begun a collaboration with a regional science museum and is developing ideas to build an exhibition booth to make public be aware of climate change and ice core research. All data will be archived at the National Snow and Ice Data Center and at other similar archives per the OPP data policy. | None | None | false | false | ||||
Opal Burial in the Pacific Sector of the Southern Ocean: A Test of the "Silicic Acid Leakage Hypothesis."
|
0230268 |
2009-01-12 | Anderson, Robert; Burckle, Lloyd |
|
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.<br/><br/>Intellectual Merit<br/>This 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". <br/><br/>The "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. <br/><br/>An 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's phytoplankton assemblage include:<br/> a) an increase in the global average organic carbon/calcium carbonate ratio of particulate biogenic material sinking into the deep sea;<br/> b) a reduction in the preservation and burial of calcium carbonate in marine sediments;<br/> c) an increase in ocean alkalinity as a consequence of the first two changes mentioned above, and;<br/> d) a lowering of atmospheric CO2 concentrations in response to increased alkalinity of ocean waters. <br/><br/>A 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. <br/><br/>Previous 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. <br/><br/>Significance and Broader Impacts<br/>Determining 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. <br/><br/>During 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's 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. | 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)) | POINT(-140 -57.5) | false | false |