Soil Moisture Mapping Using Sar Imagery

Abstract

' Retrieval of soil moisture from microwave remote sensing data has become the corner stone of many land surfacelatmospheric interaction and global hydrology studies and scientific plans. Recently, a number of microwave multisensor aircraft experiments has been devised in order to develop and evaluate techniques for soil moisture retrieval. During the MACHYDRO-90 experiment held in Mahantango watershed in central Pennsylvania, JPL AIRSAR multi-frequency and multi-polarization data were collected over an eleven day period. The main objective of this experiment was to map the spatial distribution of soil moisture and its changes with time within a basin. The research basin is a 7 sq km instrumented watershed. The area is confined by mountains with rolling terrain of elevations between 200 and 300 m and intensively cultivated. JPL AIRSAR was flown over the area four times during the experiment in order to acquire multiple incident angle (20°, 30°, 45') at P, L, and C band over a range of soil moisture conditions from 8% to 25% in volumetric unit. The radar returns from corner reflectors deployed in the watershed have been used to calibrate the system for channel imbalance, cross talk and absolute radiometric calibration. The overflight data acquisition was supported by in situ measurements of soil and vegetation parameters.