COMPARISONS OF REMOTELY-SENSED AND MODEL-SIMULATED SOIL-MOISTURE OVERA HETEROGENEOUS WATERSHED

Soil moisture estimates from a distributed hydrologic model and two mi crowave airborne sensors (Push Broom Microwave Radiometer and Syntheti c Aperture Radar) are compared with ground measurements on two differe nt scales, using data collected during a field experiment over a 7.4-k m2 heterogeneous watershed located in central Pennsylvania. It is foun d that both microwave sensors and the hydrologic model successfully re flect the temporal variation Of soil moisture. Watershed-averaged soil moistures estimated by the microwave sensors are in good agreement wi th ground measurements. The hydrologic model initialized by streamflow records yields estimates that are wetter than observations. The preli minary test of utilizing remotely sensed information as a feedback to correct the initial state of the hydrologic model shows promising resu lts.