HR: 09:15h
AN: H21J-06    [Abstracts]
TI: The Determination of Soil Hydraulic Properties From Surface Temperature and the Effect of Errors in Other Model Parameters
AU: * Gutmann, E D
EM: ethan.gutmann@colorado.edu
AF: University of Colorado, Boulder, Department of Geological Sciences, Campus Box 399 2200 Colorado Ave., Boulder, CO 80309-0399, United States
AU: Small, E E
EM: Eric.Small@colorado.edu
AF: University of Colorado, Boulder, Department of Geological Sciences, Campus Box 399 2200 Colorado Ave., Boulder, CO 80309-0399, United States
AB: Soil hydraulic properties (SHPs) are perhaps the least well constrained parameters in land surface models. Other land surface model parameters (e.g. vegetation type and cover, albedo, slope, and roughness) are observable at the land surface, and thus are amenable to measurement by satellite. However, SHPs have no clear representation at the surface, and thus are largely unknown. Present estimates of soil properties come from maps of soil texture, and have been shown to be extremely poor (r²=0.05). Previous work has suggested that calibrating SHPs using remotely sensed surface temperature has promise. Here, we show that using surface temperature to calibrate SHPs can dramatically improve model estimates of evapotranspiration. This process decreases mid-day RMS errors from 110 to 60W/m² (4.2 to 2.3 mm/day), and decreases the bias from 30 to 2 W/m² (from 1.1 to 0.076 mm/day). However, this requires that all other parameters in the model are reasonably well known. Errors in parameters such as surface roughness, or in input data such as solar radiation or air temperature can cause the SHP estimation process to increase errors in evapotranspiration in attempts to compensate. Errors in other evapotranspiration sources (e.g. precipitation, ground water availability, or vegetation cover) lead to errors in the estimated SHPs, but these errors offset each other, and the bias between modeled and measured evapotranspiration is reduced.
DE: 1818 Evapotranspiration
DE: 1840 Hydrometeorology
DE: 1843 Land/atmosphere interactions (1218, 1631, 3322)
DE: 1846 Model calibration (3333)
DE: 1878 Water/energy interactions (0495)
SC: Hydrology [H]
MN: 2007 Fall Meeting