HR: 1340h
AN: C33A-0338    [Abstracts]
TI: A Snow Accumulation Map For the Dry Snow Region of Greenland Derived from InSAR Correlation Observations
AU: * Oveisgharan, S
EM: shadio@stanford.edu
AF: Departments of Geophysics and Electrical Engineering Stanford University, 397 Panama Mall, Stanford, CA 94305-2215 United States
AU: Zebker, H A
EM: zebker@stanford.edu
AF: Departments of Geophysics and Electrical Engineering Stanford University, 397 Panama Mall, Stanford, CA 94305-2215 United States
AB: Snow accumulation in remote regions such as Greenland and Antarctica is often estimated from radar brightness or reflectivity. However, incompleteness of the radar scattering models used results in inaccuracies in the derived accumulation maps. Even maps derived from in situ ice core stations are not completely accurate because of the sparseness of the stations in these areas. We have developed an interferometric ice scattering model that relates insar correlation and reflecting to ice grain size and layer spacing, and can be used to invert the radar observations. Accumulation rates derived by our improved method showed superior agreement with in situ core measurements for a small area in the dry snow zone of Greenland, while other models using only reflectivity data match poorly. Our model's improvements follow because larger grain size and thicker annual layers both make a radar image brighter; the first corresponds to lower accumulation and the second corresponds to higher accumulation. However, addition of correlation data can resolve the ambiguity seen using brightness only. Here we apply our method for estimating snow accumulation rates to a larger area of Greenland. Raw RADARSAT-1 data acquired from the Alaska Satellite Facility, collected between September and December of 2000, are currently being processed. Raw data about 400GB in size are required to form interferograms of the entire Greenland area. Accumulation rates for the dry snow zone are derived by applying our new model to radar reflectivity and correlation of these C-band RADARSAT-1 data. The high resolution of the map derived from insar remote sensing data leads to an accurate and detailed map of accumulation. Comparison of our model inversion results and in situ core measurements for this large area will show whether our new method is applicable for the entire Greenland dry snow zone.
DE: 6964 Radio wave propagation
DE: 1827 Glaciology (1863)
DE: 1863 Snow and ice (1827)
DE: 1640 Remote sensing
DE: 0933 Remote sensing
SC: Cryosphere [C]
MN: 2004 AGU Fall Meeting