Spatial Correlation Structure of Soil Moisture from Aircraft to Satellite Footprint Scales During SGP97 and SGP99

The Spatial correlation structure of soil moisture content from aircraft to satellite remote sensing footprint scale is presented using in situ and remotely sensed data from the SGP'97 and SGP'99 experiments. At the aircraft footprint scale, the correlation scale of moderately wet fields decreases from approximately 75 m to 7 m as the drying period progresses, without significant change in semi-variance. At the satellite footprint scale, the remotely sensed region is partitioned to remove the large scale trend of soil moisture variability created by precipitation, based on the antecedent rainfall data. Persistent spatial correlation features of soil moisture are observed over both the wet and dry regions, with correlation lengths from 15 to 30 km. The factors affecting the spatial features of the soil moisture distribution are discussed by analyzing the spatial statistics of ancillary data such as soil texture, vegetation water content, topography, and precipitation.