Analysis of bidirectional reflectance effects on 20 years AVHRR NDVI data for agricultural regions in Ukraine and Russia

The Normalized Difference Vegetation Index (NDVI), provide synoptic information on environmental conditions in agricultural regions such as in Ukraine and Russia. However, past studies have raised questions whether the Maximum Value Compositing (MVC) method, used to produce time-series of NDVI, is affected by Bidirectional Reflectance Distributions (BRD), as a result of view geometry, possibly leading to erroneous NDVI values. This study uses Angular Dependence Models (ADM), derived the NOAA/NASA Pathfinder AVHRR Land (PAL) data set, to correct PAL Channels 1 & 2 reflectance for BR. MVC is used to produce ten day NDVI composites, from both the pre-BRD correct channels and the BRD corrected channels. Comparisons of the two NDVI time-series show a slight increase in NDVI for the