C-Band RISAT-1 Data for Crop Growth Assessment of Rice

The recently launched Indian satellite RISAT-1 in microwave region removes the limitations of optical sensors with “all-weather”, day or night imaging capabilities and is anticipated to be a useful data sources for rice crop monitoring in tropical and sub-tropical regions. The main purpose of this study was to analyze the temporal behavior of rice backscatter of two types of rice (basmati and non-basmati) growing simultaneously and; to assess the potential of dual-polarized C-band RISAT-1 data to estimate the Leaf area index (LAI) of paddy rice. Four Medium Resolution ScanSAR (MRS) dual-polarization (HH/HV) mode RISAT-1 data were acquired as per the growth stage over the part of Karnal district, India in kharif season of year 2012 and ground data (crop height, leaf area index (LAI), canopy moisture etc.) were collected during the same period of the satellite pass. Furthermore, with the use of multi-temporal RISAT-1 data, the backscatter of rice in different polarizations over entire growth period was analyzed and LAI was estimated using a semi-empirical model based on simplified Michigan Microwave Canopy Scattering (MIMICS) Model by fitting it at the same time of RISAT-1 data acquisition. Finally estimated LAI from the proposed model was compared with ground measurements. The accuracy of LAI obtained from the model needs to be increased for high LAI value (>3.8). Nevertheless, the model showed the noticeable result for LAI estimation of rice using HV backscatter and provided the promising approach for growth monitoring using SAR data.