Soil Moisture Influences on the Radar Backscattering of Sugar Beet Fields

The objective of this article is to investigate the possibility of soil 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 from a vegetated surface, viz., the model developed by Karam et al. (1995) and the model developed by Lang (1981). First, we validate the models based on data from the AGRISCATT’88 field campaign, held in Flevoland, The Netherlands. The data collected during this campaign allows us to test the model predictions 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 configuration and 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 concluded that estimates of surface soil moisture content under a medium sugar beet cover (15 cm high crop) from L-band radar observations are only possible within 10% accuracy. For a fully developed sugar beet field (50 cm high crop), soil moisture retrieval is not possible.