Atmospheric Pollution in the Indo-Gangetic Plains and Its Impacts on Vegetation Cover during 2000-2012

Indian agriculture is highly dependent on the timely and good monsoon. In recent years, due to increasing atmospheric pollution, monsoon circulation and rainfall distribution are getting affected over the Indian region. Prior to the onset of the monsoon, northern India is influenced by significant dust storms, these dusts are transported up to Far East of Indo-Gangetic Plains (IGP). The long range of transport constitutes the bulk of the regional aerosol loading over the IGP. Here a multi-sensor characterization of the increasing pre-monsoon aerosol loading over the northern India, in terms of their spatial and temporal distribution and its association with rain fall is presented. The association of rainfall with NDVI and EVI is also presented here. Aerosol transport from the northwestern arid regions into the IGP and over the foothills of the Himalayas is found. Detailed analysis of the monsoon rainfall, aerosol optical depth and normalized vegetation index over the IGP region during 2000-2012 has been carried out; early summer monsoon rainfall reduces the atmospheric aerosols. Annual, inter-annual and regional variations in aerosol characteristics, rainfall, NDVI and EVI over IGP during the last one decade and their correlations show characteristics features. High AOD during pre-monsoon season over the IGP is dependent on the winter/spring rainfall and soil moisture. The high value of AOD is again observed during post monsoon seasons and winter season; AOD is minimum in equinox months. The overall AOD peak little falls as the time advances. The NDVI and EVI show good correlation with the rainfall in IGB and the maxima peak of NDVI and EVI are found to increase. The maximum accumulated rain is during July-August of each year show one to one correspondence with maximum EVI during August-September, whereas NDVI peak occur during August. The maxima EVI peak shows a time lag of one month with maxima peak of rainfall. Rainfall and NDVI show positive correlation especially during monsoon season. AOD and NDVI-EVI show a negative correlation. The magnitude of correlation differs from region to region due to changes in agro-climatic conditions. The maxima of NDVI and EVI from 2000 to 2012 are correlated with maxima of seasonal rainfall. The percent NDVI, EVI, AOD and rainfall variations provide directly good qualitative and quantitative information over IGP. Such information can be available in real time that will be of great use to agricultural planners. Changes in NDVI and EVI are found to be highly correlated with rainfall distribution during monsoon season but not in summer season.