Estimating evapotranspiration over Yosemite National Park using a regional ecosystem model driven by satellite-based climate data.

Estimation of evapotranspiration over complex terrains is difficult because of the sparse distribution of ground- based observations and the large errors associated with extrapolating these data. Satellites, however, provide spatially continuous and consistent observations of key climate and vegetation variables, which may help us to overcome this difficulty. Here, we report our effort to estimate evapotranspiration over Yosemite National Park using a regional ecosystem model driven by satellite data (MODIS, GOES, and TM). The Terrestrial Observation and Prediction System (TOPS) was used in this study to simulate water and carbon fluxes. We also used the Variable Infiltration Capacity (VIC) routing model for validation of simulated water budgets using the discharge data at two locations in the park. The estimated evapotranspiration was reasonable both in terms of its spatial variability and in relation to the discharge data. Compared to other climate interpolation methods, this method is computationally inexpensive and can capture more detail for patchy regions like fire scares and logged areas.