An Agroecological Modeling Approach to Explain ERS SAR Radar Backscatter of Agricultural Crops

An agroecological approach is presented to simulate time series of ERS SAR radar backscatter of agricultural crops from integrated crop growth (SUCROS), water balance (SAHEL), and radar backscatter (Cloud) modeling. SUCROS is used to calculate the amount of water in canopies and SAHEL the amount of water in the top soil, which serve both as driving variables for the Cloud model. The methodology was tested on three years of ERS SAR observations, 1992–1994, over an agricultural area in Flevoland, The Netherlands. Area-average model input data and radar backscatter values per crop type were used. Observed temporal radar backscatter curves of sugar beet, potato, and winter wheat were reproduced well with 1–2 dB accuracy in all three years using the same set of SUCROS, SAHEL, and Cloud model parameters per crop type each year. Main reasons for success were the use of “area-average” instead of “field-average” data, the flatness of the area, the relative homogeneity in agroecological conditions, and the near-potential growing conditions.