HR: 0800h
AN: C21A-0058    [Abstracts]
TI: Snow Cover Mapping at the Continental to Global Scale Using Combined Visible and Passive Microwave Satellite Data
AU: * Armstrong, R L
EM: rlax@nsidc.org
AF: NSIDC/CIRES University of Colorado, UCB 449, Boulder, CO 80309, United States
AU: Brodzik, M
EM: brodzik@nsidc.org
AF: NSIDC/CIRES University of Colorado, UCB 449, Boulder, CO 80309, United States
AU: Savoie, M H
EM: savoie@nsidc.org
AF: NSIDC/CIRES University of Colorado, UCB 449, Boulder, CO 80309, United States
AB: Over the past several decades both visible and passive microwave satellite data have been utilized for snow mapping at the continental to global scale. Snow mapping using visible data has been based primarily on the magnitude of the surface reflectance, and in more recent cases on specific spectral signatures, while microwave data can be used to identify snow cover because the microwave energy emitted by the underlying soil is scattered by the snow grains resulting in a sharp decrease in brightness temperature and a characteristic negative spectral gradient. Both passive microwave and visible data sets indicate a similar pattern of inter-annual variability, although the maximum snow extents derived from the microwave data are consistently less than those provided by the visible satellite data and the visible data typically show higher monthly variability. We describe the respective problems as well as the advantages and disadvantages of these two types of satellite data for snow cover mapping and demonstrate how a multi-sensor approach is optimal. For the period 1978 to present we combine data from the NOAA weekly snow charts with snow cover derived from the SMMR and SSM/I brightness temperature data. For the period since 2002 we blend NASA EOS MODIS and AMSR-E data sets. Our current product incorporates MODIS data from the Climate Modelers Grid (CMG) at approximately 5 km (0.05 deg.) with microwave-derived snow water equivalent (SWE) at 25 km, resulting in a blended product that includes percent snow cover in the larger grid cell whenever the microwave SWE signal is absent. Validation of AMSR-E at the brightness temperature level is provided through the comparison with data from the well-calibrated heritage SSM/I sensor over large homogeneous snow-covered surfaces (e.g. Dome C region, Antarctica). We also describe how the application of the higher frequency microwave channels (85 and 89 GHz)enhances accurate mapping of shallow and intermittent snow cover.
UR: http://nsidc.org
DE: 0736 Snow (1827, 1863)
DE: 0758 Remote sensing
DE: 0764 Energy balance
DE: 0776 Glaciology (1621, 1827, 1863)
SC: Cryosphere [C]
MN: 2007 Fall Meeting