Comparison of space-based microwave polarization difference index and normalized difference vegetation index for crop growth monitoring

Abstract

This paper reports the passive microwave radiometry application for regional assessment of crop growth in India. Brightness temperature (<i>T</i>_B) of various vegetation classes observed at 37 GHz using special sensor microwave imager (SSMI) data, during Kharif season in 1999 in India are analyzed. Vertical as well as horizontal polarization brightness temperature is used to derive microwave polarization difference index (MPDI) for different crops/vegetation classes at various phenological stages. This MPDI index is related with the ten-day maximum value of composite of normalized difference vegetation index (NDVI) data of NOAA- AVHRR sensor. A non-linear inverse relationship has been developed between the MPDI and NDVI of different crops over various regions. It has been observed that the surface wetness/soil moisture in rice growing region influenced the MPDI-NDVI relationship.