HR: 1340h
AN: H33E-0515    [Abstracts]
TI: Comparing Different Estimates of Evaporation Coefficient From Two-Stage Evaporation of Soil Surfaces
AU: * Wu, J
EM: jindong@umn.edu
AF: Department of Soil, Water, and Climate University of Minnesota, 439 Borlaug Hall, 1991 Upper Buford Circle, St Paul, MN 55108 United States
AU: Wang, D
EM: wangd@umn.edu
AF: Department of Soil, Water, and Climate University of Minnesota, 439 Borlaug Hall, 1991 Upper Buford Circle, St Paul, MN 55108 United States
AB: Evaporation coefficient ({\it K}$_{E}$) allows for estimation of soil evaporation without in situ measurements. In this study, a resistance based method ({\it K}$_{E}$$^{r}$) and a temperature based method ({\it K}$_{E}$$^{t}$) for estimating {\it K}$_{E}$ were compared with high-frequency measurements of two-stage soil evaporation. An alternative method ({\it K}$_{E}$$^{a}$) for estimating {\it K}$_{E}$ was presented in which soil surface resistance ({\it r}$_{s}$) was computed with temperature differences between surface and overlying air ({\it T}$_{r}$-{\it T}$_{a}$). Results indicated that more accurate estimates of {\it K}$_{E}$ were found in the first stage than in the second stage. Compared to the measurements, the {\it K}$_{E}$$^{r}$ method produced the best estimates with a correlation coefficient ({\it r}$^{2}$) of 0.88, a root-mean-square-difference (RMSD) of 0.04, and a mean-absolute-difference (MAD) of 0.03. The {\it K}$_{E}$$^{t}$ method overestimated in both stages of evaporation with the lowest {\it r}$^{2}$ (0.30) and largest RMSD (0.14) and MAD (0.13). The {\it K}$_{E}$$^{a}$ method produced estimates of {\it K}$_{E}$ comparable to the {\it K}$_{E}$$^{r}$ method, which was a significant improvement from the {\it K}$_{E}$$^{t}$ method. The correlation coefficient between {\it K}$_{E}$$^{a}$ and measurements was 0.64, and the RMSD and MAD was 0.05 and 0.04, respectively. Future investigations should focus on improving the functional relationship between {\it r}$_{s}$ and ({\it T}$_{r}$-{\it T}$_{a}$).
DE: 3360 Remote sensing
DE: 1818 Evapotranspiration
DE: 1833 Hydroclimatology
DE: 1866 Soil moisture
DE: 1878 Water/energy interactions
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting