USAP-DC

{"dp_type": "Project", "free_text": "depth-age scale"}

[{"awards": "0944199 Waddington, Edwin", "bounds_geometry": null, "dataset_titles": "WAIS Divide Sonic Log Data", "datasets": [{"dataset_uid": "609592", "doi": "10.7265/N5T72FD2", "keywords": "Antarctica; Glaciers/ice Sheet; Glaciers/Ice Sheet; Ice Core Records; Physical Properties; Sonic Log; WAIS Divide; WAIS Divide Ice Core", "people": "McCarthy, Michael; Waddington, Edwin D.; Matsuoka, Kenichi; Kluskiewicz, Dan; Anandakrishnan, Sridhar", "repository": "USAP-DC", "science_program": "WAIS Divide Ice Core", "title": "WAIS Divide Sonic Log Data", "url": "https://www.usap-dc.org/view/dataset/609592"}], "date_created": "Wed, 03 Sep 2014 00:00:00 GMT", "description": "0944199/Matsuoka\u003cbr/\u003e\u003cbr/\u003eThis award supports a project to test the hypothesis that abrupt changes in fabric exist and are associated with both climate transitions and volcanic eruptions. It requires depth-continuous measurements of the fabric. By lowering a new logging tool into the WAIS Divide borehole after the completion of the core drilling, this project will measure acoustic-wave speeds as a function of depth and interpret it in terms of ice fabrics. This interpretation will be guided by ice-core-measured fabrics at sparse depths. This project will apply established analytical techniques for the ice-sheet logging and estimate depth profiles of both compressional- and shear-wave speeds at short intervals (~ 1 m). Previous logging projects measured only compressional-wave speeds averaged over typically 5-7 m intervals. Thus the new logger will enable more precise fabric interpretations. Fabric measurements using thin sections have revealed distinct fabric patterns separated by less than several meters; fabric measurements over a shorter period are crucial. At the WAIS Divide borehole, six two-way logging runs will be made with different observational parameters so that multiple wave-propagation modes will be identified, yielding estimates of both compressional- and shear-wave speeds. Each run takes approximately 24 hours to complete; we propose to occupy the boreholes in total eight days. The logging at WAIS Divide is temporarily planned in December 2011, but the timing is not critical. This project?s scope is limited to the completion of the logging and fabric interpretations. Results will be immediately shared with other WAIS Divide researchers. Direct benefits of this data sharing include guiding further thin-section analysis of the fabric, deriving a precise thinning function that retrieves more accurate accumulation history and depth-age scales. The PIs of this project have conducted radar and seismic surveys in this area and this project will provide a ground truth for these regional remote-sensing assessments of the ice interior. In turn, these remote sensing means can extend the results from the borehole to larger parts of the central West Antarctica. This project supports education for two graduate students for geophysics, glaciology, paleoclimate, and polar logistics. The instrument that will be acquired in this project can be used at other boreholes for ice-fabric characterizations and for englacial hydrology (wetness of temperate ice).", "east": null, "geometry": null, "instruments": "IN SITU/LABORATORY INSTRUMENTS \u003e PROBES \u003e PROBES", "is_usap_dc": true, "keywords": "WAIS Divide; GROUND STATIONS; Western Divide Core; Antarctic Ice Sheet", "locations": "Antarctic Ice Sheet; WAIS Divide", "north": null, "nsf_funding_programs": "Antarctic Glaciology", "paleo_time": null, "persons": "Matsuoka, Kenichi; Kluskiewicz, Dan; Anandakrishnan, Sridhar; McCarthy, Michael; Waddington, Edwin D.", "platforms": "LAND-BASED PLATFORMS \u003e PERMANENT LAND SITES \u003e GROUND STATIONS", "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": "WAIS Divide Ice Core", "south": null, "title": "Collaborative research: acoustic logging of the WAIS Divide borehole", "uid": "p0000051", "west": null}, {"awards": "0087521 Waddington, Edwin", "bounds_geometry": null, "dataset_titles": "Annual Layers at Siple Dome, Antarctica, from Borehole Optical Stratigraphy", "datasets": [{"dataset_uid": "609515", "doi": "10.7265/N5DB7ZRZ", "keywords": "Antarctica; Borehole Optical Stratigraphy; Geology/Geophysics - Other; Glaciers/ice Sheet; Glaciers/Ice Sheet; Glaciology; Siple Dome; Siple Dome Ice Core; Snow/ice; Snow/Ice", "people": "Hawley, Robert L.; Taylor, Kendrick C.; Waddington, Edwin D.; Alley, Richard", "repository": "USAP-DC", "science_program": "Siple Dome Ice Core", "title": "Annual Layers at Siple Dome, Antarctica, from Borehole Optical Stratigraphy", "url": "https://www.usap-dc.org/view/dataset/609515"}], "date_created": "Sun, 15 Apr 2012 00:00:00 GMT", "description": "This award supports a two year project to develop a new method for measuring vertical strain rates in polar firn. Vertical strain rate measurements in the firn are important because they can aid in the understanding of the dynamics of firn compaction, a key factor in determining ice age/gas age difference estimates for ice cores. Vertical strain rate measurements also determine ice advection for borehole paleothermometry models, and most importantly can be used to date the shallow sections of ice cores where ambiguities in chemical dating or counting of annual layers hinder dating by traditional methods. In this project a video logging tool will be used to create a unique \"optical fingerprint\" of variations in the optical properties of the firn with depth, and track the movement and deformation of the features of this fingerprint. Preliminary work at Siple Dome, Antarctica using an improvised logging system shows a series of optically bright and dark zones as the tool transits up or down the hole. Borehole fingerprinting has the potential to improve measurements of vertical strain in firn holes. This project represents a unique opportunity to interface with an existing field program where a borehole vertical strain rate project is already underway. A graduate student will be supported to conduct the work on this project as part of a PhD. dissertation on climate and physical processes in polar firn.", "east": null, "geometry": null, "instruments": "EARTH REMOTE SENSING INSTRUMENTS \u003e PASSIVE REMOTE SENSING \u003e PHOTON/OPTICAL DETECTORS \u003e CAMERAS \u003e CAMERAS", "is_usap_dc": true, "keywords": "Antarctica; Stratigraphy; Layers; Ice Core Stratigraphy; Siple Dome; Borehole; FIELD INVESTIGATION; Borehole Camera; Ice Stratigraphy", "locations": "Antarctica; Siple Dome", "north": null, "nsf_funding_programs": "Antarctic Glaciology", "paleo_time": null, "persons": "Alley, Richard; Taylor, Kendrick C.; Waddington, Edwin D.; Hawley, Robert L.", "platforms": "LAND-BASED PLATFORMS \u003e FIELD SITES \u003e FIELD INVESTIGATION", "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": "Siple Dome Ice Core", "south": null, "title": "Borehole Fingerprinting: Vertical Strain, Firn Compaction, and Firn Depth-Age Scales", "uid": "p0000173", "west": null}, {"awards": "0538639 Waddington, Edwin", "bounds_geometry": "POLYGON((-112.1 -79.4,-112.09 -79.4,-112.08 -79.4,-112.07 -79.4,-112.06 -79.4,-112.05 -79.4,-112.04 -79.4,-112.03 -79.4,-112.02 -79.4,-112.01 -79.4,-112 -79.4,-112 -79.41,-112 -79.42,-112 -79.43,-112 -79.44,-112 -79.45,-112 -79.46,-112 -79.47,-112 -79.48,-112 -79.49,-112 -79.5,-112.01 -79.5,-112.02 -79.5,-112.03 -79.5,-112.04 -79.5,-112.05 -79.5,-112.06 -79.5,-112.07 -79.5,-112.08 -79.5,-112.09 -79.5,-112.1 -79.5,-112.1 -79.49,-112.1 -79.48,-112.1 -79.47,-112.1 -79.46,-112.1 -79.45,-112.1 -79.44,-112.1 -79.43,-112.1 -79.42,-112.1 -79.41,-112.1 -79.4))", "dataset_titles": null, "datasets": null, "date_created": "Thu, 01 Apr 2010 00:00:00 GMT", "description": "0538639\u003cbr/\u003eWaddington\u003cbr/\u003eThis award supports a project to study the patterns of accumulation variation and microstructural properties near the WAIS Divide ice core site in a 2.5 km array of 20 m boreholes. Borehole Optical Stratigraphy (BOS) is a novel optical measurement system that detects annual-scale layers in firn that result from changes in firn microstructure, giving annual-scale records of how accumulation varied spatially over the last 40-50 years. Data from borehole optical stratigraphy can eventually be calibrated against other data on the microstructural parameters of firn to calibrate BOS\u0027s sensitivity to density, pore-volume, and pore-shape variations, and to show by proxy how these parameters vary in space across the survey area. Statistical analysis of layer-thickness and layer-brightness data will enable prediction of: 1) interannual accumulation variability, 2) variability in layer-thickness at decadal scales due to changing spatial patterns in accumulation and 3) variability in microstructure-driven metamorphism due to changing spatial patterns of microstructure. With these statistics in hand, a scientist measuring climatic shifts found in the WAIS Divide ice core will be able to determine the fraction by which signals they measure exceed the signal due to background accumulation variations. As an added benefit, while still in the field, we will determine a preliminary depth-age scale for the firn by optical layer-counting, to the depth of the deepest air-filled firn hole available. This will be a valuable result for core-drilling operations and for preliminary data-analysis on the core. In terms of broader impacts, this project will advance education by training a post-doctoral student in field techniques. The P.I. and the post-doctoral researcher will participate in an undergraduate seminar called \"What is Scientific Research?\", incorporating progress and results from this project. They will also communicate about their progress and field experience with a middle-school science and math class.", "east": -112.0, "geometry": "POINT(-112.05 -79.45)", "instruments": "IN SITU/LABORATORY INSTRUMENTS \u003e RECORDERS/LOGGERS \u003e OPTICAL DUST LOGGERS", "is_usap_dc": false, "keywords": "Spatial Variability; FIELD INVESTIGATION; Not provided; LABORATORY; Stratigraphy; Borehole Optical Stratigraphy; Optical Layer-Counting; Microstructure; Firn; Depth-Age-Model; Optical; WAIS Divide; FIELD SURVEYS; Accumulation", "locations": "WAIS Divide", "north": -79.4, "nsf_funding_programs": "Antarctic Glaciology", "paleo_time": null, "persons": "Fudge, T. J.; Waddington, Edwin D.", "platforms": "LAND-BASED PLATFORMS \u003e FIELD SITES \u003e FIELD INVESTIGATION; LAND-BASED PLATFORMS \u003e FIELD SITES \u003e FIELD SURVEYS; Not provided; OTHER \u003e PHYSICAL MODELS \u003e LABORATORY", "repositories": null, "science_programs": null, "south": -79.5, "title": "Spatial Variability in Firn Properties from Borehole Optical Stratigraphy at the Inland WAIS Core Site", "uid": "p0000237", "west": -112.1}]

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