Biophysical parameter assessment of winter crops using polarimetric variables—entropy (H), anisotropy (A), and alpha (α).

The study brings out the potential of SAR polarimetric time series data for the study of crop biophysical parameter assessment of major winter field crops in India. We examined the entropy-alpha-anisotropy approach in radar polarimetric C-band data and related the polarimetric parameters to the biomass to understand the interaction of microwave signal with the major winter crops across dominant biomass ranges in India. The crop phenology response in terms of the changes in polarimetric parameters like entropy (H), anisotropy (A), and alpha (α) angle and their derived parameters has been studied for dominant winter field crops like wheat, mustard, and gram with variation in their variables like biomass. A trend is established emerging from this study which shows that entropy, alpha, and anisotropy for agricultural areas are closely related to the growth rate of the crops and their phenological stages. This paper outlines a methodology for using RADARSAT-2 full-polarimetric data for vegetation (winter crops) monitoring using the abovementioned standard polarimetric parameters for understanding crop vigor and phenology. The polarimetric parameters were observed to be more dynamic in wheat (H 0.45 to 0.8) than in mustard (H 0.6 to 0.85) in December to February data though late sown crop of mustard showed a higher range with respect to their biomass. [ABSTRACT FROM AUTHOR]