Long term (2003–2012) spatio-temporal MODIS (Terra/Aqua level 3) derived climatic variations of aerosol optical depth and cloud properties over a semi arid urban tropical region of Northern India

Aerosol optical depth (AOD) values at 550 nm derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor onboard NASAʹs Terra and Aqua satellites, for the 10 years period of 2003–2012 have been analyzed in the present study. The retrieved satellite data (Terra/Aqua) has been used to investigate the temporal heterogeneity in columnar aerosol characteristics over a semi arid urban tropical Delhi zone (28° 34′, 77° 07′, 233 m ASL) of Northern India with a resolution of 1° × 1° grid in magnitude. Aerosol optical depths have found to be increased >25% across Delhi region of India during the study period of 2003–2012. Yearly mean Terra/Aqua AOD values have shown an increasing trend at a rate of 0.005/0.009 per year respectively. However, seasonally winter means Terra/Aqua AOD values exhibit an increasing trend at a rate of ∼0.012/0.007 per year respectively. In order to provide a better understanding of aerosol–cloud interaction, a single paired one tailed distribution studentʹs t-Test has been applied to the Terra AOD values and cloud parameters. The results extracted in the present study are compared with the earlier studies as well as with the AOD values over various other Indian regions.