New hyperspectral vegetation characterization parameters Original Research Article

The Near Infrared (NIR) bands for Indian Remote Sensing (IRS)/ Linear Imaging Self Scanning (LISS), Landsat TM and NOAA AVHRR are in 770–860, 760–900 and 725–1100 nm region. These NIR bands include water vapour absorption bands. To improve the biomass related intelligence of Normalized Difference Vegetation Index (NDVI), spectral region in NIR has to be chosen by excluding water vapour absorption bands in a manner that the existing dynamic range is maintained. Based on 3 nm bandwidth measurements over Wheat, it was found that reflected radiance in NIR had peaks at 747 nm and 777 nm, respectively. New Vegetation Index (NVI) was constructed by ratioing the difference of peak radiances at 777 and 747 nm with reflected radiance at 673 nm in Red region by using 3, 10 and 20 nm bandwidths. The 3 and 10 nm bandwidths gave nearly similar values of NVI. Thus estimation of this NVI is possible from 10 nm bandwidth data sets becoming available from space-based platforms in the near future. The rate of change of this NVI for wheat crop during 49 – 84 Days After Sowing (DAS) was comparatively very high than that for Ratio Vegetation Index (RVI) which conveys about the high sensitivity of NVI during peak vegetative through reproductive stages for wheat. The ratio of difference in radiance from chlorophyll-β (centered at 640 nm) and chlorophyll-α (centered at 673 nm) to that for chlorophyll-α depicted high sensitivity during maturity (and initial) stage.