Gutmann, Ethan D听1听;听Small, Eric E听2
1听University of Colorado
2听University of Colorado
Soil Hydraulic Properties (SHPs) play an important role in regulating heat and moisture fluxes in land surface models. Currently, SHPs are estimated from soil texture class. However, studies have shown that this method is inadequate because there is as much variability within a texture class as there is between classes (Gutmann and Small 2005). Therefore, a new method of determining SHPs is required. We investigate the potential to determine SHPs from remotely sensed surface temperature (Ts). Ts is related to SHPs because soil moisture controls evaporative cooling of the surface as well as thermal conductivity of the soil. We use the Noah land surface model to investigate the sensitivity of Ts to SHPs in semi-arid environments from central New Mexico, Kansas, and Oklahoma. To do this, we run the model with one set of SHPs. We then add random errors to the model output Ts signal and use this degraded Ts signal to determine SHPs through a model inversion. This process is repeated for each SHP in a large database of measured SHPs and the Ts derived SHPs are compared to the "true" SHPs. Our results indicate that, at error levels comparable to reported satellite Ts errors, we are able to determine SHPs three times better using Ts than we can from soil texture class.
Gutmann, E., and E. Small 2005, The effect of soil hydraulic properties vs. soil texture in land surface models: Geophysical Research Letters, v.32. no.2, L02402 10.1029/2004GL021843