Submitted to: IEEE Transactions on Geoscience and Remote Sensing
Publication Type: Proceedings
Publication Acceptance Date: January 7, 1997
Publication Date: N/A
Interpretive Summary: There are currently three orbiting satellite-based sensors that are measuring the backscatter of microwave energy from the earth's surface. This measurement of backscatter could supply farmers with important information about their crop and soil conditions. However, the backscatter is also influenced by conditions that are not of interest to the farmer, such as row direction and soil roughness. We used a physical model to discriminate the information that would be useful to the farmer (crop biomass and soil moisture) from that which was relatively inconsequential. The combination of the backscatter measurements with the simulation model resulted in accurate, field-by-field maps of crop biomass and surface soil moisture. Such maps could provide farmers with the information necessary to make decisions on water, fertilizer, and insecticide applications.
A method is proposed to estimate both green leaf area index (GLAI) and soil moisture (hv) based on radar measurements at the Ku-band (14.85 GHZ) and C-band (5.35 GHZ) frequencies. The Ku-band backscatter at large incidence angles was found to be independent of soil moisture conditions, and could be used alone to estimate GLAI. Then, the Ku-band estimate of GLAI could be used with a measurement of C-band backscatter in a canopy radiative transfer model to isolate the value of hv. This concept was demonstrated with a limited set of Ku- and C-band SAR backscatter data acquired over agricultural fields in Arizona. The demonstration showed some promise for operational application of the method, though several limitations were identified.