Submitted to: International Journal of Remote Sensing
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/1/2003
Publication Date: 11/20/2003
Citation: Oldak, A., Jackson, T.J., Starks, P., Elliott, R. 2003. Mapping near-surface soil moisture on regional scale using ERS-2 SAR data. International Journal of Remote Sensing. 24(22):4579-4598. Interpretive Summary: European Radar Satellite-2 C-band, vertically polarized, synthetic aperture radar satellite sensor data were used to provide regional estimates of surface soil moisture distribution. Radar data were acquired for three contiguous scenes in the Southern Great Plains region of central Oklahoma from June 1999 through October 2000. These data were compared with ground measurements at selected test sites. Soil moisture maps for El Reno and Little Washita test areas were produced based on linear relationship between soil moisture and backscattering coefficient. The regional mapping component is a unique element of this investigation. Radar remote sensing has great potential in studies requiring high spatial resolution. These results will contribute to the potential operational implementation of this technique in hydrologic, climate and agricultural applications.
Technical Abstract: Soil moisture is an important hydrologic variable of great consequence in both natural and agricultural ecosystems. Unfortunately, it is virtually impossible to accurately assess the spatial and temporal variability of surface soil moisture using conventional, point measurement techniques. Remote sensing has the potential to provide areal estimates of soil moisture at a variety of spatial scales. This investigation evaluates the use of European Remote Sensing Satellite (ERS-2) C-band, VV polarization, synthetic aperture radar data for regional estimates of surface soil moisture. Radar data were acquired for three contiguous ERS-2 scenes in the Southern Great Plains (SGP) region of central Oklahoma from June 1999 through October 2000. Twelve test sites (each approximately 800 m x 800 m) were sampled during the ERS-2 satellite overpasses in order to monitor changes in soil moisture and vegetation on the ground. An average radar backscattering coefficient was calculated for each test site. Landsat 5 and 7 Thematic Mapper (TM) scenes of the experimental sites close in time to the ERS-2 acquisition dates were also analyzed. The TM scenes were used to monitor land cover changes and to calculate the Normalized Difference Vegetation Index (NDVI). Land cover and ground data were used to interpret the radar-derived soil moisture data. Linear relationships between soil moisture and the backscattering coefficient were established. Using these equations, soil moisture maps of the Little Washita and the El Reno test areas were produced.