Regional and temporal patterns of soil moisture during CLASIC using passive microwave satellite observations

摘要

The Cloud Land Surface Interaction Campaign (CLASIC) was conducted in Oklahoma during the summer of 2007, with a primary focus on the interaction between cloud formation and land surface processes, including surface soil moisture. Passive microwave observations were used to study the evolution of soil moisture conditions over the Southern Great Plains and to evaluate the potential of using this data to monitor and map flooded areas. The analyses presented here used the TMI satellite instrument. As part of the investigation, the effect of atmospheric water vapour on the microwave observations was evaluated. Atmospheric water vapour effects can be significant for high frequency microwave observations (as much as 50 K for 89 GHz and 20 K for 36.5 GHz). The effect of atmospheric water vapour decreases significantly for low frequency observations (4 K for 10 GHz). Soil moisture estimates were validated using ground and meteorological observations. The estimated soil moisture was in good agreement with in situ observations (RMSE = 0.044 m~3/m~3) and reflected the temporal variations resulting from precipitation events. The range and variability of estimated soil moisture was a function of land surface variables (vegetation and soils). Reliable soil moisture estimates will contribute to the study of the interaction between cloud formation and land surface.