USAP-DC

{"dp_type": "Dataset", "free_text": "Solar Activity"}

[{"awards": "0944197 Waddington, Edwin", "bounds_geometry": ["POINT(-112.1115 -79.481)"], "date_created": "Tue, 28 Mar 2017 00:00:00 GMT", "description": "The West Antarctic Ice Sheet Divide (WAIS Divide, WD) ice core is a newly drilled, high-accumulation deep ice core that provides Antarctic climate records of the past ~68 ka at unprecedented temporal resolution. The upper 2850 m (back to 31.2 ka BP) have been dated using annual-layer counting. Here we present a chronology for the deep part of the core (67.8-31.2 ka BP), which is based on stratigraphic matching to annual-layer-counted Greenland ice cores using globally well-mixed atmospheric methane. We calculate the WD gas age-ice age difference (Delta age) using a combination of firn densification modeling, ice-flow modeling, and a data set of d15N-N2, a proxy for past firn column thickness. The largest Delta age at WD occurs during the Last Glacial Maximum, and is 525 +/- 120 years. Internally consistent solutions can be found only when assuming little to no influence of impurity content on densification rates, contrary to a recently proposed hypothesis. We synchronize the WD chronology to a linearly scaled version of the layer-counted Greenland Ice Core Chronology (GICC05), which brings the age of Dansgaard-Oeschger (DO) events into agreement with the U/Th absolutely dated Hulu Cave speleothem record. The small Delta age at WD provides valuable opportunities to investigate the timing of atmospheric greenhouse gas variations relative to Antarctic climate, as well as the interhemispheric phasing of the \\\"bipolar seesaw\\\".\n\nWe present the WD2014 chronology for the upper part (0-2850 m; 31.2 ka BP) of the West Antarctic Ice Sheet (WAIS) Divide (WD) ice core. The chronology is based on counting of annual layers observed in the chemical, dust and electrical conductivity records. These layers are caused by seasonal changes in the source, transport, and deposition of aerosols. The measurements were interpreted manually and with the aid of two automated methods. We validated the chronology by comparing to two high-accuracy, absolutely dated chronologies. For the Holocene, the cosmogenic isotope records of 10Be from WAIS Divide and 14C for IntCal13 demonstrated that WD2014 was consistently accurate to better than 0.5% of the age. For the glacial period, comparisons to the Hulu Cave chronology demonstrated that WD2014 had an accuracy of better than 1% of the age at three abrupt climate change events between 27 and 31ka. WD2014 has consistently younger ages than Greenland ice core chronologies during most of the Holocene. For the Younger Dryas-Preboreal transition (11.595 ka; 24 years younger) and the Bolling-Allerod Warming (14.621 ka; 7 years younger), WD2014 ages are within the combined uncertainties of the timescales. Given its high accuracy, WD2014 can become a reference chronology for the Southern Hemisphere, with synchronization to other chronologies feasible using high-quality proxies of volcanism, solar activity, atmospheric mineral dust, and atmospheric methane concentrations.", "east": -112.1115, "geometry": ["POINT(-112.1115 -79.481)"], "keywords": "Antarctica; Depth-Age-Model; Geochronology; Glaciers/ice Sheet; Glaciers/Ice Sheet; Glaciology; Ice Core Records; WAIS Divide; WAIS Divide Ice Core", "locations": "WAIS Divide; Antarctica", "north": -79.481, "nsf_funding_programs": null, "persons": "Fudge, T. J.", "project_titles": "Collaborative Research: Establishing the Chronology and Histories of Accumulation and Ice Dynamics for the WAIS Divide Core", "projects": [{"proj_uid": "p0000026", "repository": "USAP-DC", "title": "Collaborative Research: Establishing the Chronology and Histories of Accumulation and Ice Dynamics for the WAIS Divide Core"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": "WAIS Divide Ice Core", "south": -79.481, "title": "WD2014: Timescale for WAIS Divide Core 2006 A (WDC-06A)", "uid": "601015", "west": -112.1115}, {"awards": "1245821 Brook, Edward J.", "bounds_geometry": ["POINT(162.167 -77.733)"], "date_created": "Fri, 01 Jan 2016 00:00:00 GMT", "description": "This award supports a project to use the Taylor Glacier, Antarctica, ablation zone to collect ice samples for a range of paleoenvironmental studies. A record of carbon-14 of atmospheric methane (14CH4) will be obtained for the last deglaciation and the Early Holocene, together with a supporting record of CH4 stable isotopes. In-situ cosmogenic 14C content and partitioning of 14C between different species (14CH4, C-14 carbon monoxide (14CO) and C-14 carbon dioxide (14CO2)) will be determined with unprecedented precision in ice from the surface down to ~67 m. Further age-mapping of the ablating ice stratigraphy will take place using a combination of CH4, CO2, and delta 18O of oxygen gas and H2O stable isotopes. High precision, high-resolution records of CO2, delta 13C of CO2, nitrous oxide (N2O) and N2O isotopes will be obtained for the last deglaciation and intervals during the last glacial period. The potential of 14CO2 and Krypton-81 (81Kr) as absolute dating tools for glacial ice will be investigated. The intellectual merit of proposed work includes the fact that the response of natural methane sources to continuing global warming is uncertain, and available evidence is insufficient to rule out the possibility of catastrophic releases from large 14C-depleted reservoirs such as CH4 clathrates and permafrost. The proposed paleoatmospheric 14CH4 record will improve our understanding of the possible magnitude and timing of CH4 release from these reservoirs during a large climatic warming. A thorough understanding of in-situ cosmogenic 14C in glacial ice (production rates by different mechanisms and partitioning between species) is currently lacking. Such an understanding will likely enable the use of in-situ 14CO in ice at accumulation sites as a reliable, uncomplicated tracer of the past cosmic ray flux and possibly past solar activity, as well as the use of 14CO2 at both ice accumulation and ice ablation sites as an absolute dating tool. Significant gaps remain in our understanding of the natural carbon cycle, as well as in its responses to global climate change. The proposed high-resolution, high-precision records of delta 13C of CO2 would provide new information on carbon cycle changes both during times of rising CO2 in a warming climate and falling CO2 in a cooling climate. N2O is an important greenhouse gas that increased by ~30% during the last deglaciation. The causes of this increase are still largely uncertain, and the proposed high-precision record of N2O concentration and isotopes would provide further insights into N2O source changes in a warming world. The broader impacts of proposed work include an improvement in our understanding of the response of these greenhouse gas budgets to global warming and inform societally important model projections of future climate change. The continued age-mapping of Taylor Glacier ablation ice will add value to this high-quality, easily accessible archive of natural environmental variability. Establishing 14CO as a robust new tracer for past cosmic ray flux would inform paleoclimate studies and constitute a valuable contribution to the study of the societally important issue of climate change. The proposed work will contribute to the development of new laboratory and field analytical systems. The data from the study will be made available to the scientific community and the broad public through the NSIDC and NOAA Paleoclimatology data centers. 1 graduate student each will be trained at UR, OSU and SIO, and the work will contribute to the training of a postdoc at OSU. 3 UR undergraduates will be involved in fieldwork and research. The work will support a new, junior UR faculty member, Petrenko. All PIs have a strong history of and commitment to scientific outreach in the forms of media interviews, participation in filming of field projects, as well as speaking to schools and the public about their research, and will continue these activities as part of the proposed work. This award has field work in Antarctica.", "east": 162.167, "geometry": ["POINT(162.167 -77.733)"], "keywords": "Antarctica; Atmosphere; Geochemistry; Ice Core Records; Isotope; Paleoclimate; Taylor Glacier; Transantarctic Mountains", "locations": "Taylor Glacier; Transantarctic Mountains; Antarctica", "north": -77.733, "nsf_funding_programs": null, "persons": "Brook, Edward J.", "project_titles": "Collaborative Research: The Taylor Glacier, Antarctica, Horizontal Ice Core: Exploring changes in the Natural Methane Budget in a Warming World and Expanding the Paleo-archive", "projects": [{"proj_uid": "p0000283", "repository": "USAP-DC", "title": "Collaborative Research: The Taylor Glacier, Antarctica, Horizontal Ice Core: Exploring changes in the Natural Methane Budget in a Warming World and Expanding the Paleo-archive"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -77.733, "title": "The Taylor Glacier, Antarctica, Horizontal Ice Core: Exploring changes in the Natural Methane Budget in a Warming World and Expanding the Paleo-archive", "uid": "600163", "west": 162.167}, {"awards": "0538683 Lal, Devendra", "bounds_geometry": ["POINT(-180 -90)"], "date_created": "Thu, 01 Jan 2009 00:00:00 GMT", "description": "The principal aim of this research is to determine the precise manner in which solar activity has varied in the past 1000 years. During this period, four periods of very low solar activity have been identified: Wolf (1305-1345 AD), Spoerer (1418-1540 AD), Maunder (1645-1715), and one period of high solar activity (1100-1250 A.D.) have been deduced based on available historical records of sunspot numbers and aurora. Our proposal aims to study the solar activity during the past 1000 years in detail using a new method, based on studies of polar ice, as developed earlier (Earth and Planetary Science Letters, 234, 335-349, 2005). The method is based on the fact that greater solar activity leads to production of greater magnetic fields in the heliosphere, which reduces the primary cosmic ray flux in the near Earth environment, and vice-versa. Consequently if one can measure the primary cosmic ray flux in the near Earth space, it becomes a direct measure of the solar activity. Lal et al. (Earth and Planetary Science Letters, 234, 335-349, 2005) concluded that the best way of measuring the primary cosmic ray flux would be to measure the concentration of cosmogenic in-situ produced 14C in polar ice sheets, which was discovered by Lal et al. (Nature 346, 350-352, 1990). Following this idea Lal et al. (op. cit.) measured cosmogenic in-situ produced in 19 samples from the GISP 2 core covering time range of 375-31,250 yrs B.P. Their studies showed that there were two periods of very low solar activity in this time bracket (during 8500-9500 B.P and 27,000-32,000 B.P.), and one high solar activity period during 12,000-16,000 yrs B.P. In order to provide an independent check on the veracity of the new method, we decided to apply it to the historical period, \u003c 1000 yrs B.P. The inferred Solar activities based on the study of cosmogenic in-situ produced 14C in South Pole ice samples clearly establish that there was a period of high Solar activity during 1100-1250 A.D., and a period of very low solar activity during 1416-1534 A.D, designated as the Spoerer Minimum. These results however do not confirm the proposed dates for the Dalton and the Maunder Minimum periods, predicted to be 1795-1825 A.D. and 1654-1714 A.D. respectively. Instead, our studies show that there was a long duration period of low solar activity during 1750-1860 A.D. These results make it quite clear that we should carry out more studies to fully establish the temporal behavior of the Solar activity in the past 1000 yrs.", "east": -180.0, "geometry": ["POINT(-180 -90)"], "keywords": "Antarctica; Carbon-14; Cosmos; Geochemistry; Glaciers/ice Sheet; Glaciers/Ice Sheet; Glaciology; Ice Core Records; Paleoclimate; Solar Activity; South Pole", "locations": "South Pole; Antarctica", "north": -90.0, "nsf_funding_programs": null, "persons": "Lal, Devendra", "project_titles": "Solar Activity during the Last Millennium, Estimated from Cosmogenic in-situ 14C in South Pole and GISP2 Ice Cores", "projects": [{"proj_uid": "p0000555", "repository": "USAP-DC", "title": "Solar Activity during the Last Millennium, Estimated from Cosmogenic in-situ 14C in South Pole and GISP2 Ice Cores"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -90.0, "title": "Solar activity during the last millennium, estimated from cosmogenic in-situ C14 in South Pole and GISP2 ice cores", "uid": "600058", "west": -180.0}, {"awards": "0739620 Bieber, John", "bounds_geometry": ["POLYGON((-180 -60,-144 -60,-108 -60,-72 -60,-36 -60,0 -60,36 -60,72 -60,108 -60,144 -60,180 -60,180 -63,180 -66,180 -69,180 -72,180 -75,180 -78,180 -81,180 -84,180 -87,180 -90,144 -90,108 -90,72 -90,36 -90,0 -90,-36 -90,-72 -90,-108 -90,-144 -90,-180 -90,-180 -87,-180 -84,-180 -81,-180 -78,-180 -75,-180 -72,-180 -69,-180 -66,-180 -63,-180 -60))"], "date_created": "Thu, 01 Jan 2009 00:00:00 GMT", "description": "This proposal seeks funding to continue the neutron monitor observations at McMurdo for at least 4 years of operation - through the next solar activity maximum predicted in 2011-12. The neutron monitor in McMurdo is a crucial element of the \u0027Spaceship Earth\u0027 array - a 12-station multi-national network of neutron monitors optimized to measure the angular distribution of relativistic solar cosmic rays. McMurdo has the southernmost viewing direction of any neutron monitor station in the World, thereby providing a critical three-dimensional perspective on the cosmic ray distribution measured by the global array. Data returned from McMurdo and other \u0027Spaceship Earth\u0027 stations will enable the advanced understanding of the acceleration and transport of solar energetic particles, and of the transient and long-term modulation of galactic cosmic rays by the Sun. From the historical occurrence rates, continuing McMurdo observations through the solar activity maximum would allow to detect new relativistic solar particle events. Neutron monitors can play a direct role in forecasting and specifying solar wind disturbances, thus improving the capability to forecast major space weather events for the societal benefit. For example, providing the cosmic rays Ground-Level Enhancement (GLE) alerts is of direct relevance to aviation flights over high latitudes where these events can pose health hazards.", "east": 180.0, "geometry": ["POINT(0 -89.999)"], "keywords": "Antarctica; Atmosphere; Cosmic Ray; McMurdo; Neutron Monitor", "locations": "McMurdo; Antarctica", "north": -60.0, "nsf_funding_programs": null, "persons": "Evenson, Paul; Bieber, John", "project_titles": "Cosmic Ray Observations in McMurdo", "projects": [{"proj_uid": "p0000679", "repository": "USAP-DC", "title": "Cosmic Ray Observations in McMurdo"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -90.0, "title": "Cosmic Ray Observations in McMurdo", "uid": "600078", "west": -180.0}, {"awards": "0126343 Nishiizumi, Kunihiko", "bounds_geometry": ["POINT(-148.812 -81.6588)"], "date_created": "Thu, 31 May 2007 00:00:00 GMT", "description": "This data set includes a record of cosmogenic radionuclide concentrations in the Siple Dome A ice core collected as part of the West Antarctic ice core program. The investigators measured profiles of both \u003csup\u003e10\u003c/sup\u003eBe (half-life = 1.5x10\u003csup\u003e6\u003c/sup\u003e years) and \u003csup\u003e36\u003c/sup\u003eCl (half-life = 3.0x10\u003csup\u003e5\u003c/sup\u003e years) in the entire ice core, which spans the time period from the present to about 100,000 years before present. These data are being used for perfecting the ice core chronology, deducing the history of solar activity, deducing the history of variations in the geomagnetic field, and studying the possible role of solar variations on climate. \n\nData are distributed as a PDF file and are available via FTP.", "east": -148.812, "geometry": ["POINT(-148.812 -81.6588)"], "keywords": "Antarctica; Geochemistry; Geochronology; Glaciers/ice Sheet; Glaciers/Ice Sheet; Glaciology; Ice Core Records; Paleoclimate; Siple Dome; Siple Dome Ice Core", "locations": "Siple Dome; Antarctica", "north": -81.6588, "nsf_funding_programs": "Antarctic Glaciology", "persons": "Finkel, R. C.; Nishiizumi, Kunihiko", "project_titles": "Cosmogenic Radionuclides in the Siple Dome Ice Core", "projects": [{"proj_uid": "p0000358", "repository": "USAP-DC", "title": "Cosmogenic Radionuclides in the Siple Dome Ice Core"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": "Siple Dome Ice Core", "south": -81.6588, "title": "Cosmogenic Radionuclides in the Siple Dome A Ice Core", "uid": "609307", "west": -148.812}]

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