Fractional snow cover in the Colorado and Rio Grande basins, 1995-2002
- Author(s): Bales, RC
- Dressler, KA
- Imam, B
- Fassnacht, SR
- Lampkin, D
- et al.
Published Web Locationhttp://onlinelibrary.wiley.com/doi/10.1029/2006WR005377/abstract?systemMessage=Wiley+Online+Library+will+be+unavailable+on+Saturday+27th+February+from+09:00-14:00+GMT+/+04:00-09:00+EST+/+17:00-22:00+SGT+for+essential+maintenance.++Apologies+for+the+inconvenience.
A cloud-masked fractional snow-covered area (SCA) product gridded at 1 km was developed from the advanced very high resolution radiometer for the Colorado River and upper Rio Grande basins for 1995-2002. Cloud cover limited SCA retrievals on any given 1-km2 pixel to on average once per week. There were sufficient cloud-free scenes to map SCA over at least part of the basins up to 21 days per month, with 3 months having only two scenes sufficiently cloud free to process. In the upper Colorado and upper Grande, SCA peaked in February-March. Maxima were 1-2 months earlier in the lower Colorado. Averaged over a month, as much as 32% of the upper Colorado and 5.5% of the lower Colorado were snow covered. Snow cover persisted longest at higher elevations for both wet and dry years. Interannual variability in snow cover persistence reflected wet-dry year differences. Compared with an operational (binary) SCA product produced by the National Operational Hydrologic Remote Sensing Center, the current products classify a lower fraction of pixels as having detectable snow and being cloud covered (5.5% for SCA and 6% for cloud), with greatest differences in January and June in complex, forested terrain. This satellite-derived subpixel determination of snow cover provides the potential for enhanced hydrologic forecast abilities in areas of complex, snow-dominated terrain. As an example, we merged the SCA product with interpolated ground-based snow water equivalent (SWE) to develop a SWE time series. This interpolated, masked SWE peaked in April, after SCA peaked and after some of the lower-elevation snow cover had melted. Copyright 2008 by the American Geophysical Union.