Application of "Observation Minus Reanalysis" Method towards LULC Change Impact over Southern India

This study performed a land use and land cover (LULC) change analysis over Southern India for the period 1981-2006 from the normalized difference vegetation index (NDVI) images of AVHRR data and applied the "observation minus reanalysis" (OMR) method to investigate the impact of the LULC change on the temperature of the region. The LULC change analysis indicated that the areas under agriculture/fallow land were significantly increased while the areas under shrubs/small vegetation were decreased during the period 1981-2006. The areas under forest cover and barren land were also decreased but relatively low compared to the other LULC types. The OMR results showed that the LULC changes over urban areas contributed to warming with a temperature of 0.02 degrees C during this period, while that over non-urban areas showed a cooling effect with a temperature reduction of 0.29 degrees C and that over the whole Southern India (looked at an average) indicated a cooling effect with a temperature reduction of 0.063 degrees C. The comparative analysis between the two (LULC change analysis and OMR) results showed that the cooling over Southern India was mostly due to the expansion of agriculture/fallow land and the decline of shrubs/small vegetation. The study suggests that the OMR method reasonably demonstrates the effect of LULC changes on the temperature over Southern India.