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Developing a Method for Estimating Accumulation Rates using CReSIS airborne Snow Radar from West Antarctica For more than 50 years, scientists have retrieved ice cores from the world's ice sheets to study ice dynamics as well as past and present climatic and atmospheric conditions, including the accumulation rate. The ice-sheet accumulation rate is not only an important climate indicator but also a significant component of ice-sheet mass balance, which is the total mass gained or lost over a prescribed period of time [1]. Snow accumulation is the primary mass contributor while ice flux into the ocean and surface melting are the primary mass loss mechanisms. As concern over sea-level change and ice-sheet stability increases, more accurate and spatially complete estimates of the accumulation rate are required. Therefore, the sparse point estimates of the accumulation rate (i.e., ice cores) no longer give sufficient data for regional mass balance estimates because of their limited spatial coverage, but remain important paleoclimate records due to their exceptional temporal resolution. In order to constrain current mass balance estimates at the regional scale, improvement in the spatial resolution of accumulation rate estimates is necessary [2]. West Antarctica in particular is seriously lacking in point based measurements of the accumulation rate, whether through snow pit or ice core analysis. Climate models show the region along the Amundsen Coast receives snowfall amounts unprecedented across most of the continent, yet these models lack any ground-truthing and are limited in their spatial resolution [3]. Thus, any estimates of mass balance over this region are ill-constrained and are in need of much better estimates of the snow accumulation rate. Using the CReSIS developed Snow Radar, which is capable of imaging near surface layers in the uppermost part of the ice sheet at a very fine vertical resolution, estimates of very recent firn accumulation rates over the Thwaites glacier along the Amundsen Coast of West Antarctica were calculated using data from Flight One, Segment 02 of the 10/18/2009 flight. The “short” segment layer (~130.76km) mean accumulation (temporal variation, accumulation rate changing with time) rate was 0.4m/yr and the “long” segment layer (~297.874km) was 0.44m/yr. The standard deviation ( how much the accumulation rate varies in space) for the “short” segment layer was 0.052m and 0.068m for the “long” segment layer. The derived dataset estimates are within range of previous estimates; however, the continent wide published estimates do not correspond well with each other nor the specific dataset for Thwaites Glacier. |
:: :: Validation of the 2003 Antartic Groundling Line through the use of ENVI Dynamics and mass balance of an ice sheet can be derived from an accurate measurement of its area. To measure the area of a continental ice sheet, the grounding line must first be accurately determined. The grounding line is the boundary between the ‘grounded’ ice resting on land and any associated floating ice comprising a retaining ice shelf. During a project entitled Antarctic Surface Accumulation and Ice Discharge or ASAID, Dr. Robert Bindschadler, lead an international team of glaciologists and computer scientists, including ECSU students, in an effort to obtain a more accurate measure of the area of the Antarctic ice sheet and determine its mass balance. That is, whether the amount of ice is growing or diminishing over long time intervals. Bindschadler’s team determined the grounding line using methods of photoclinometry with LANDSAT Enhanced Thematic Mapper (ETM) image brightness and surface elevation data from the Geoscience Laser Altimeter System (GLAS) aboard NASA’s Ice, Land and Cloud Elevation Satellite (ICESat). The ASAID grounding line (GL) was established using LANDSAT 7 and GLAS data obtained in 2003. However its accuracy and utility had not been tested. With the current ASAID 2003 Grounding Line (GL), the CERSER GL Validation Team was tasked by Dr. Bindschadler with determining its accuracy in two coastal regions and whether changes have occurred over long time intervals. The team over-laid the 2003 GL on LANDSAT Seven ETM imagery temporally proximate to 2003. This modified image was then compared to decades older LANDSAT 4 & 5 Thematic Mapper (TM) imagery. GL validation and change determination were planned for two geographic areas known to exhibit rapid changes potentially due to climate warming: Pine Island Glacier (PIG) and Larsen Ice Shelf. However, due to time constraints, the team only examined a limited portion of the PIG. The GL was tested along a portion of the Antarctic coast near the PIG. To accomplish the validation, LANDSAT 7 images from 2003 used in creating the GL, were obtained from the USGS archive (lima.usgs.gov). Other LANDSAT images were obtained from the USGS GLOVIS on-line archive (glovis.usgs.gov). The oldest possible, cloud-free LANDSAT 4 and 5 TM images were obtained for the regions of interest. To facilitate data manipulation and image comparisons, the extremely large GL vector file, obtained from Dr. Bindschadler. was truncated to include only the geographic regions of interest. Truncation and image comparisons were accomplished using ITT Visualization System’s ENVI image processing software. Any departure from perfect geographic pixel registration was corrected by using the 2003 image as a reference and then warping the older image to conform to the common fixed control points visible on both images. The grounding line overlying the 2003 image was then examined and compared to the older image. The geographic coordinates and extent of any departures from coincidence were recorded and reported. A possible deviation in the GL was found while comparing a 2001 LANDSAT 7 image to a 1986 LANDSAT 5 image, near a small glacier feeding into Pine Island Bay. Comparison with a 2003 image of the same area revealed no GL inaccuracy; however a small ice shelf appeared to have progressively diminished over time until it disappeared in 2003. |
:: :: Undergraduate Research Experience in Ocean, Marine, and Polar Science 2010 Throughout North America’s eastern coastal plain are found a variety of features attributed to ice age climate. These include many elliptical, shallow depressions called collectively Carolina Bays, hypothesized to have been formed by the strong, sustained winds and arid, cold climate characteristic of glacial epochs (Raisz, 1934, Johnson, 1942 and Kaczorowski, 1977). This view eclipsed the 1933 proposition by Melton and Schriever, and expanded by Prouty (1934, 1953), that extraterrestrial debris produced by an aerial meteorite or comet explosion in the vicinity of the Great Lakes during the late Pleistocene formed the bays. Recent discovery that a number of the bays were found to contain materiel associated with extraterrestrial impacts including carbon and magnetic spherules, glass-like carbon, charcoal and nanodiamonds reinvigorated the debate over the bay’s origins (Firestone, et. al. 2007). |
:: :: NSF-Watershed Watch 2009 Abstract Most people don't know that they could be contributing to adverse water quality changes right in their own backyards. How? Well because, we all live in watersheds, an area that drains to a common waterway. In order to determine how development, farmlands and water treatment plants affect water quality, we visited various locations near agriculture sites, urban development and waste treatment facilities along the Pasquotank River, the Washington Ditch, and the Great Dismal Swap in Southeastern Virginia and Northeastern North Carolina. At each location we measured of pH levels, temperature, water clarity, apparent /true color, specific conductivity, turbidity, zooplankton abundance, and the amount of chlorophyll a. We found that as we moved down river into increasing agriculture and development the water clarity decreased and conductivity increased. When we moved towards the city, “away from the swamp headwaters” dissolved color decreased and the pH increased. The lowest clarity was found in downtown Elizabeth City; we also noted that the highest chlorophyll readings were located at the sewage treatment plant. Additional water quality results supported our initial hypothesis that the quality of the water decreased with the extent of land use. |
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