Cooperative Institute for Research in Environmental Sciences

Science Rendezvous > 2009 Posters
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High-Resolution Airborne Polarimetric Microwave Imaging of Snow Cover During the NASA Cold Lands Processes Experiment (CLPX)

B. Boba Stankov, D. Cline, B. L. Weber, G. A. Wick, and A. J. Gasiewski

We present a detailed analysis of the airborne passive microwave remote sensing data that were collected at a broad range of microwave bands and at high spatial resolution during the 2002 and 2003 NASA Cold Lands Processes Experiment (CLPX). Accurate measurement of snowpack properties using passive microwave observations requires detailed knowledge of the relationship between snowpack geophysical parameters and the upwelling polarimetric brightness signature. The principle microwave instrument used for CLPX was the Polarimetric Scanning Radiometer (PSR), which provided ~100-m resolution maps of snow emissivity at all Advanced Microwave Scanning Radiometer for EOS (AMSR-E) bands during several intensive observation periods over the Colorado Rocky Mountains.

Observed conditions included drought, normal snowpack, and spring snowmelt. The PSR and related ground-based observations of snowpack properties made during the 2002 and 2003 CLPX campaigns provide a comprehensive high-resolution passive microwave data set.

Results show that the high-resolution PSR data exhibit emissivity modes similar to those observed in the historical data sets and that the empirical relationships between emissivity and the snow water equivalent (SWE), after the effects of macro-vegetation are removed, closely match those found in the past theoretical studies. Use of the 89 GHz channel in the empirical relationships provides improved accuracy under dry snow conditions and small SWE, but the variability of the SWE-emissivity relationships increases with increasing SWE. A summary of the observed relationships between the emissivity spectra of snow and snowpack properties is presented. Comparison of the total water content from the AMSR-E and the PSR observations shows that the satellite measurements underestimated the total volume of water storage from airborne observations on the average by a factor of five.