HR: 1330h
AN: H32B-0566    [PDF]
TI: The Testing of AMSR-E Snow Depth and Snow Water Equivalent Estimates in the Northern Hemisphere
AU: * Chang, A T
EM: al.chang@nasa.gov
AF: NASA Goddard Space Flight Center, NASA/GSFC Code 974 Hydrological Sciences Branch, Greenbelt, MD 20771
AU: Kelly, R E
EM: rkelly@ltpmail.gsfc.nasa.gov
AF: NASA Goddard Space Flight Center, NASA/GSFC Code 974 Hydrological Sciences Branch, Greenbelt, MD 20771
AU: Kelly, R E
EM: rkelly@ltpmail.gsfc.nasa.gov
AF: Goddars Earth Science and Technology Center, UMBC, GEST/UMBC, Baltimore, MD 21250
AU: Foster, J L
EM: jfoster@ltpmail.gsfc.nasa.gov
AF: NASA Goddard Space Flight Center, NASA/GSFC Code 974 Hydrological Sciences Branch, Greenbelt, MD 20771
AU: Hall, D K
EM: dhall@glacier.gsfc.nasa.gov
AF: NASA Goddard Space Flight Center, NASA/GSFC Code 974 Hydrological Sciences Branch, Greenbelt, MD 20771
AB: Accurate estimation of snow mass is important for effective characterization of the hydrological cycle at different space and time scales. In the global hydrological cycle, not only does snow constitute a critical seasonal and long-term storage factor but it also affects global climate mass and energy dynamics. Satellite passive microwave observations have been used to estimate global snow depth and snow water equivalent (SWE) since 1979. However, during this time the instruments available have been able to observe snow mass over spatial domains only at regional scales; finer scale observations have not been possible. The Advanced Microwave Scanning Radiometer - EOS launched in 2002 aboard NASA's Aqua platform, has improved spatial resolution capabilities compared with previous passive microwave instruments and, potentially, can be used to estimate snow depth and SWE with increased accuracy at the regional scale. This paper describes refinements to the snow water equivalent products that are being developed for AMSR-E. The baseline retrieval algorithm uses the brightness temperature difference between 18 and 36 GHz channels to estimate snow depth and SWE. Two important refinements under development are described that attempt to better constrain the retrieval algorithm with respect to the effect of grain size and forest cover. Both these factors are known to affect the naturally upwelling microwave radiation from snow. Testing of the refined approach is conducted using daily measurements of snow depth from the World Meteorological Organization (WMO) Global Telecommunications System (GTS) archive. We examine the accuracy of the snow depth estimates at the global scale and also in three regions: Colorado Rocky Mountains, USA, Canadian Prairies and Finland. Each region represents a different "snow regime" and is affected by grain size evolution and forest cover in different ways. Additionally, for each region, WMO/GTS data are augmented by locally collected ground data to produce a more comprehensive ground test data set. The paper demonstrates the accuracy of the refined AMSR-E product and how important the need is to account for grain size and forest cover effects.
DE: 1863 Snow and ice (1827)
SC: Hydrology [H]
MN: 2003 Fall Meeting