Detection of Prairie Grassland Mowing Using Polarimetric Microwave Radar

Remote sensing methods have historically been used to monitor grassland vegetation height as changes may be accompanied by negative environmental impacts. Previous studies analyzed the suitability of satellites for monitoring grassland mowing and grazing events, but there is limited knowledge of the usability of ground-based systems for this purpose. The goal of this study was to determine if C- and L-band ground based scatterometers could be used to detect and quantify changes in grass height. We compared the normalized radar cross sections (NRCS) of C- and L-band scatterometers before and after a grassland mowing event. Co-polarized (VV, HH) and cross-polarized signals were analyzed at the elevation angles of 30° and 55° for both scatterometer systems. Results showed as much as 5.1 dB decrease in backscatter for C-band occurred after the mowing event. The decrease at L-band was less significant (2.4 dB at most). The results of this study confirmed that ground-based scatterometer systems operating in C- and L-band can be used to detect mowing events.