Simple time integrations of AVHRR/NDVI (Normalized Difference Vegetation Index) have been correlated with annual net primary production of terrestrial vegetation; yet this implies seasonally constant physiological efficiency of the vegetation. We present logic for a time integrated NDVI that is modified by an AVHRR derived surface evaporation resistance factor σ, and truncated by temperatures that cause plant dormancy, to improve environmental sensitivity. With our approach, NDVI observed during sub-freezing temperatures is not integrated. Water stress related impairment in plant activity is incorporated by reducing the effective NDVI at each integration with the surface resistance factor, σ. The surface resistance factor is derived from the slope of the surface temperature to NDVI ratio for climatically similar zones of the scene. A comparison of surface resistance before and after an extended drought period for a 1200km2 region of coniferous forest in Montana will be presented.
|Number of pages
|Proceedings of SPIE - The International Society for Optical Engineering
|Published - 1990
|Remote Sensing of the Biosphere - Orlando, FL, USA
Duration: Apr 19 1990 → Apr 20 1990