SOIL-MOISTURE INFLUENCES ON THE RADAR BACKSCATTERING OF SUGAR-BEET FIELDS

The objective of this article is to investigate the possibility of soi l moisture retrieval from radar backscatter data in sugar beet fields. The analysis Is based on a simulation study using two models capable of computing electromagnetic backscattering front a vegetated surface, ci;., the model developed by Karam et al. (1995) and the model develo ped by Lang (1981). First, we validate the models based on data front, the AGRISCATT'88 field campaign, held in Flevoland, The Netherlands. The data collected during this campaign allows Its to test the model p redictions under different soil surface and canopy conditions and for different radar configurations. In general, both models are capable of mimicking the change in backscattering due to changes in radar config uration nod surface-vegetation characteristics. Next, both models are subjected to a sensitivity analysis with respect to different surface and canopy parameters. Based on this.sensitivity analysis, it is concl uded that estimates of surface soil moisture content under a medium su gar beet cover (15 cm high crop) from L-band radar observations are on ly possible within 10% accuracy. For a fully developed sugar beet fiel d (50 nn high crop), soil moisture retrieval is not possible. (C)Elsev ier Science Inc., 1998.