HR: 14:35h
AN: C42B-04    [PDF]
TI: Assessing Scale Effects on Snow Water Equivalent Retrievals Using Airborne and Spaceborne Passive Microwave Data
AU: * Derksen, C
EM: chris.derksen@ec.gc.ca
AF: Climate Research Branch Meteorological Service of Canada, 4905 Dufferin Street, Downsview, ON M3H 5T4 Canada
AU: Walker, A
EM: anne.walker@ec.gc.ca
AF: Climate Research Branch Meteorological Service of Canada, 4905 Dufferin Street, Downsview, ON M3H 5T4 Canada
AU: Goodison, B
EM: barry.goodison@ec.gc.ca
AF: Climate Research Branch Meteorological Service of Canada, 4905 Dufferin Street, Downsview, ON M3H 5T4 Canada
AB: The Climate Research Branch (CRB) of the Meteorological Service of Canada (MSC) has a long-standing research program focused on the development of methods to retrieve snow cover information from passive microwave satellite data for Canadian regions. Algorithms that derive snow water equivalent (SWE) have been developed by CRB and are used to operationally generate SWE information over landscape regions including prairie, boreal forest, and taiga. New multi-scale research datasets were acquired in Saskatchewan, Canada during February 2003 to quantify the impact of spatially heterogeneous land cover and snowpack properties on passive microwave SWE retrievals. MSC microwave radiometers (6.9, 19, 37, and 85 GHz) were flown on the National Research Council (NRC) Twin Otter aircraft at two flying heights along a grid of flight lines, covering a 25 by 25 km study area centered on the Old Jack Pine Boreal Ecosystem Research and Monitoring Site (BERMS). Spaceborne Special Sensor Microwave/Imager (SSM/I) and Advanced Microwave Scanning Radiometer (AMSR-E) brightness temperatures were also acquired for this region. SWE was derived for all passive microwave datasets using the CRB land cover sensitive algorithm suite. An intensive, coincident ground sampling program characterized in situ snow depth, density, water equivalent and pack structure using a land cover based sampling scheme to isolate the variability in snow cover parameters within and between forest stands and land cover types, and within a single spaceborne passive microwave grid cell. The passive microwave data sets that are the focus of this investigation cover a range of spatial resolutions from 100-150 m for the airborne data to 10 km (AMSR-E) and 25 km (SSM/I) for the satellite data, providing the opportunity to investigate and compare microwave emission characteristics, SWE retrievals and land cover effects at different spatial scales. Initial analysis shows that the small footprint airborne passive microwave SWE estimates match the range and variability of the in situ measurements, indicating that passive microwave SWE retrievals can capture local scale SWE variability if the spatial resolution is sufficiently fine. The large footprint spaceborne passive microwave SWE retrievals fall into the centre of the normally distributed in situ measurements, thereby providing a reasonable integrated estimate of mean grid cell SWE, even in a complex, mixed land cover area. A suite of micrometeorological variables from seven tower sites within the study area were also acquired to aid the interpretation of the passive microwave brightness temperatures by providing key variables such as soil moisture, and soil, snow, air, and tree temperature. Land and forest cover datasets including land cover type, canopy closure, and forest stem volume were also obtained from the Canadian Forest Service. Analysis of these collective datasets will advance our understanding of important scale and process issues related to the remote estimation of SWE from passive microwave data, and complement the research activities carried out within the NASA Cold Land Processes Experiment (CLPX).
DE: 1863 Snow and ice (1827)
DE: 6969 Remote sensing
SC: Cryosphere [C]
MN: 2003 Fall Meeting