USAP-DC

{"dp_type": "Dataset", "free_text": "Southern Hemisphere"}

[{"awards": "1643551 Hansen, Samantha", "bounds_geometry": null, "date_created": "Tue, 10 Mar 2020 00:00:00 GMT", "description": "Dataset includes information on all A- and B-ranked earthquakes (see Hansen et al., 2020) recorded by the Antarctic TAMNNET seismic array that were examined for ULVZ evidence. Information on their attenuation (t*) parameter, signal-to-noise ratio, core-mantle boundary bouncepoint location, and average remainder trace standard deviation are also provided. The provided figure indicates where ULVZ evidence has been found and where possible ULVZ evidence may be indicated.", "east": null, "geometry": null, "keywords": "Antarctica; Core-Mantle Boundary; ScP; Southern Hemisphere; Ultra-Low Velocity Zones", "locations": "Southern Hemisphere; Antarctica; Antarctica", "north": null, "nsf_funding_programs": "Antarctic Earth Sciences", "persons": "Hansen, Samantha; Carson, Sarah; Garnero, Edward; Yu, Shule; Rost, Sebastian", "project_titles": "Collaborative Research: Antarctic Seismic Investigations of ULVZ Structure", "projects": [{"proj_uid": "p0010136", "repository": "USAP-DC", "title": "Collaborative Research: Antarctic Seismic Investigations of ULVZ Structure"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": null, "title": "Investigating Ultra-low Velocity Zones (ULVZs) using an Antarctic Dataset", "uid": "601265", "west": null}, {"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": "1043554 Willenbring, Jane", "bounds_geometry": ["POINT(161.5 -77.5)"], "date_created": "Wed, 09 Nov 2016 00:00:00 GMT", "description": "The PIs propose to address the question of whether ice surface melting zones developed at high elevations during warm climatic phases in the Transantarctic Mountains. Evidence from sediment cores drilled by the ANDRILL program indicates that open water in the Ross Sea could have been a source of warmth during Pliocene and Pleistocene. The question is whether marine warmth penetrated inland to the ice sheet margins. The glacial record may be ill suited to answer this question, as cold-based glaciers may respond too slowly to register brief warmth. Questions also surround possible orbital controls on regional climate and ice sheet margins. Northern Hemisphere insolation at obliquity and precession timescales is thought to control Antarctic climate through oceanic or atmospheric connections, but new thinking suggests that the duration of Southern Hemisphere summer may be more important. The PIs propose to use high elevation alluvial deposits in the Transantarctic Mountains as a proxy for inland warmth. These relatively young fans, channels, and debris flow levees stand out as visible evidence for the presence of melt water in an otherwise ancient, frozen landscape. Based on initial analyses of an alluvial fan in the Olympus Range, these deposits are sensitive recorders of rare melt events that occur at orbital timescales. For their study they will 1) map alluvial deposits using aerial photography, satellite imagery and GPS assisted field surveys to establish water sources and to quantify parameters effecting melt water production, 2) date stratigraphic sequences within these deposits using OSL, cosmogenic nuclide, and interbedded volcanic ash chronologies, 3) use paired nuclide analyses to estimate exposure and burial times, and rates of deposition and erosion, and 4) use micro and regional scale climate modeling to estimate paleoenvironmental conditions associated with melt events.\nThis study will produce a record of inland melting from sites adjacent to ice sheet margins to help determine controls on regional climate along margins of the East Antarctic Ice Sheet to aid ice sheet and sea level modeling studies. The proposal will support several graduate and undergraduates. A PhD student will be supported on existing funding. The PIs will work with multiple K-12 schools to conduct interviews and webcasts from Antarctica and they will make follow up visits to classrooms after the field season is complete.", "east": 161.5, "geometry": ["POINT(161.5 -77.5)"], "keywords": "Antarctica; Chemistry:rock; Chemistry:Rock; Cosmogenic Radionuclides; Geochronology; Glaciers/ice Sheet; Glaciers/Ice Sheet; Glaciology; Isotope; Sample/collection Description; Sample/Collection Description; Transantarctic Mountains", "locations": "Transantarctic Mountains; Antarctica", "north": -77.5, "nsf_funding_programs": null, "persons": "Willenbring, Jane", "project_titles": "Collaborative Research: Activation of high-elevation alluvial fans in the Transantarctic Mountains - a proxy for Plio-Pleistocene warmth along East Antarctic ice margins", "projects": [{"proj_uid": "p0000429", "repository": "USAP-DC", "title": "Collaborative Research: Activation of high-elevation alluvial fans in the Transantarctic Mountains - a proxy for Plio-Pleistocene warmth along East Antarctic ice margins"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -77.5, "title": "Activation of high-elevation alluvial fans in the Transantarctic Mountains - a proxy for Plio-Pleistocene warmth along East Antarctic ice margins", "uid": "600379", "west": 161.5}, {"awards": "1303896 Kirschvink, Joseph", "bounds_geometry": ["POLYGON((-57 -63,-56.9 -63,-56.8 -63,-56.7 -63,-56.6 -63,-56.5 -63,-56.4 -63,-56.3 -63,-56.2 -63,-56.1 -63,-56 -63,-56 -63.2,-56 -63.4,-56 -63.6,-56 -63.8,-56 -64,-56 -64.2,-56 -64.4,-56 -64.6,-56 -64.8,-56 -65,-56.1 -65,-56.2 -65,-56.3 -65,-56.4 -65,-56.5 -65,-56.6 -65,-56.7 -65,-56.8 -65,-56.9 -65,-57 -65,-57 -64.8,-57 -64.6,-57 -64.4,-57 -64.2,-57 -64,-57 -63.8,-57 -63.6,-57 -63.4,-57 -63.2,-57 -63))"], "date_created": "Thu, 01 Jan 2015 00:00:00 GMT", "description": "The PI will collect samples to extend the magneto-stratigraphic record of late Cretaceous sediments of the James Ross Basin, Antarctica. RAPID support will allow him to take advantage of an invitation from the Instituto Antartico Argentino (IAA) to participate on an excursion to James Ross Island in the Antarctic Peninsula. The PI hopes to collect samples that will refine the position of several geomagnetic reversals between the end of the Cretaceous long normal Chron and the lower portion of Chron 31R. The Brandy Bay locality targeted by this expedition is the best place in the basin for calibrating the biostratigraphic position of the top of the Cretaceous Long Normal Chron, which is one of the most reliable correlation horizons in the entire Geological Time Scale.\n\nThe top of the Cretaceous long normal Chron is not properly correlated to southern hemisphere biostratigraphy. Locating this event will be a major addition to understanding geological time. This expedition will provide opportunities for an undergraduate student. This project is based on a productive collaboration with an Argentine scientist.", "east": -56.0, "geometry": ["POINT(-56.5 -64)"], "keywords": "Antarctica; GPS; James Ross Basin; Sample/collection Description; Sample/Collection Description; Solid Earth", "locations": "James Ross Basin; Antarctica", "north": -63.0, "nsf_funding_programs": null, "persons": "Kirschvink, Joseph", "project_titles": "Magnetostratigraphy of Cretaceous Sediments in the James Ross Island Basin, Antarctica", "projects": [{"proj_uid": "p0000419", "repository": "USAP-DC", "title": "Magnetostratigraphy of Cretaceous Sediments in the James Ross Island Basin, Antarctica"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -65.0, "title": "Magnetostratigraphy of Cretaceous Sediments in the James Ross Island Basin, Antarctica", "uid": "600136", "west": -57.0}, {"awards": "0739780 Taylor, Kendrick", "bounds_geometry": ["POINT(-112.117 -79.666)"], "date_created": "Sat, 01 Jan 2011 00:00:00 GMT", "description": "This award supports a project to develop a 2,000-year high-temporal resolution record of biomass burning from the analysis of black carbon in the WAIS Divide bedrock ice core. Pilot data for the WAIS WD05A core demonstrates that we now have the ability to reconstruct this record with minimal impact on the amount of ice available for other projects. The intellectual merit of this project is that black carbon (BC) aerosols result solely from combustion and play a critical but poorly quantified role in global climate forcing and the carbon cycle. When incorporated into snow and ice, BC increases absorption of solar radiation making seasonal snow packs, mountain glaciers, polar ice sheets, and sea ice much more vulnerable to climate warming. BC emissions in the Southern Hemisphere are dominated by biomass burning in the tropical regions of Southern Africa, South America and South Asia. Biomass burning, which results from both climate and human activities, alters the atmospheric composition of greenhouse gases, aerosols and perturbs key biogeochemical cycles. A long-term record of biomass burning is needed to aid in the interpretation of ice core gas composition and will provide important information regarding human impacts on the environment and climate before instrumental records.", "east": -112.117, "geometry": ["POINT(-112.117 -79.666)"], "keywords": "Antarctica; Atmosphere; Black Carbon; Chemistry:ice; Chemistry:Ice; Glaciers/ice Sheet; Glaciers/Ice Sheet; Glaciology; Ice Core Records; WAIS Divide; WAIS Divide Ice Core", "locations": "WAIS Divide; Antarctica", "north": -79.666, "nsf_funding_programs": null, "persons": "Taylor, Kendrick C.", "project_titles": "WAIS DIVIDE - High Temporal Resolution Black Carbon Record of Southern Hemisphere Biomass Burning", "projects": [{"proj_uid": "p0000022", "repository": "USAP-DC", "title": "WAIS DIVIDE - High Temporal Resolution Black Carbon Record of Southern Hemisphere Biomass Burning"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": "WAIS Divide Ice Core", "south": -79.666, "title": "WAIS DIVIDE - High Temporal Resolution Black Carbon Record of Southern Hemisphere Biomass Burning", "uid": "600142", "west": -112.117}, {"awards": null, "bounds_geometry": null, "date_created": "Thu, 15 Jun 2006 00:00:00 GMT", "description": "CUB shear velocity model is created from a large data set of the surface wave fundamental model phase and group velocity measurements. Phase velocities in period range between 40 an 150 s are generously donated by Harvard University and Utrecht University. These phase velocity data sets are described by Ekstr\u00f6m et al. (1997) and Trampert and Woodhouse (1995). The group velocity measurements at periods between 16 and 200s are performed at the Center for Imaging the Earth\u0027s Interior in the University of Colorado at Boulder. The group velocities are measured with the frequency-time analysis (Levshin et al., 1989) in which for every waveform a human analyst defines the frequency range of measurements and separate the signal form a variety of noise sources (e.g., overtones, fundamental modes of different types, other earthquakes, multipaths, scattered arrivals). We used broadband waveforms following earthquakes occurred from 1997 to present and recorded at stations from both global networks (GDSN, GSN, GEOSCOPE) as well as temporary regional arrays. At present, the group velocity dataset is composed of about 200000 paths.\n\nData coverage is generally better for Rayleigh waves than for Love waves, is better at intermediate periods than at very short or very long periods, and is better in the northern than in the southern hemisphere. This heterogeneous data coverage is imposed by the distribution of seismic stations and earthquakes. Data coverage optimizes in Eurasia and is currently worst across Africa, the central Pacific, parts of the Indian Ocean, and Antarctica.", "east": null, "geometry": null, "keywords": null, "locations": null, "north": null, "nsf_funding_programs": null, "persons": "Ritzwoller, Michael", "project_titles": null, "projects": null, "repositories": null, "science_programs": null, "south": null, "title": "Upper Mantle Shear Velocity Model", "uid": "600004", "west": null}, {"awards": "9615347 Conway, Howard", "bounds_geometry": ["POLYGON((-161.5667 -79.3889,-161.44836 -79.3889,-161.33002 -79.3889,-161.21168 -79.3889,-161.09334 -79.3889,-160.975 -79.3889,-160.85666 -79.3889,-160.73832 -79.3889,-160.61998 -79.3889,-160.50164 -79.3889,-160.3833 -79.3889,-160.3833 -79.41168,-160.3833 -79.43446,-160.3833 -79.45724,-160.3833 -79.48002,-160.3833 -79.5028,-160.3833 -79.52558,-160.3833 -79.54836,-160.3833 -79.57114,-160.3833 -79.59392,-160.3833 -79.6167,-160.50164 -79.6167,-160.61998 -79.6167,-160.73832 -79.6167,-160.85666 -79.6167,-160.975 -79.6167,-161.09334 -79.6167,-161.21168 -79.6167,-161.33002 -79.6167,-161.44836 -79.6167,-161.5667 -79.6167,-161.5667 -79.59392,-161.5667 -79.57114,-161.5667 -79.54836,-161.5667 -79.52558,-161.5667 -79.5028,-161.5667 -79.48002,-161.5667 -79.45724,-161.5667 -79.43446,-161.5667 -79.41168,-161.5667 -79.3889))"], "date_created": "Wed, 14 May 2003 00:00:00 GMT", "description": "This data set measures the radioactive decay of nuclear material from Northern and Southern hemisphere nuclear testing. Firn cores were taken from three locations on Roosevelt Island, an ice dome within the Ross Ice Shelf, and were measured at increasing depth for density in kilograms per cubic meter, and for beta counts per hour per kilogram.\n\nThe data were collected between November and December of 1997. Measurements were taken incrementally down to approximately 17 meters for each of the three cores. Data are available in text format via ftp.", "east": -160.3833, "geometry": ["POINT(-160.975 -79.5028)"], "keywords": "Antarctica; Beta Count; Density; Glaciers/ice Sheet; Glaciers/Ice Sheet; Glaciology; Ice Core Records; Physical Properties; Roosevelt Island", "locations": "Roosevelt Island; Antarctica", "north": -79.3889, "nsf_funding_programs": "Antarctic Glaciology", "persons": "Conway, Howard", "project_titles": "Radar Investigations of Former Shear Margins: Roosevelt Island and Ice Stream C", "projects": [{"proj_uid": "p0000164", "repository": "USAP-DC", "title": "Radar Investigations of Former Shear Margins: Roosevelt Island and Ice Stream C"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -79.6167, "title": "Roosevelt Island Ice Core Density and Beta Count Data", "uid": "609139", "west": -161.5667}]

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