CHARACTERIZING THE ATMOSPHERE AND SPECIAL WEATHER CONDITIONS ACROSS SOUTH ASIA DURING THE TIME PERIOD OF 2010-2016

Abstract

Radiance balance of the earth is being altered by the impact of aerosols through scattering and absorbing solar radiation. Climate forcing estimation remained uncertain because of irregular spatial and temporal variation of aerosol and their complex chemical and physical properties. Atmospheric particulates and some aerosols have a vital role in radiative forcing and climate change. The South Asian region in general and the Indo-Gangetic Plains (IGP) in particular hold about 1/6th of the world’s population and is considered as one of the major hotspots of increasing atmospheric pollution. Due to growing population and globalization, South Asia is experiencing high transformations in the urban and industrial sectors. Fog is one of the meteorological/environmental phenomena which can generate significant social and economic problems especially a major havoc to air and road traffic. Meteorological stations provide information about the fog episodes only based on point observation. Continuous monitoring as well as a spatially coherent picture of fog distribution can only be possible using satellite imagery. Current study focus on winter fog episodes over South Asian region using Moderate Resolution Image Spectrometer (MODIS) Level 2 Terra Product and MODIS Aerosol Product. The datasets used in this study includes visibility data for fog categorization. Surface Air Temperature and visibility data to analyse fog forming conditions. MODIS Corrected Reflectance RGBs are used to analyse fog situation over study area. MOD04 level 2 Collection 6 data is used to study aerosol load and distribution which are characterised using aerosol type land. In order to study the variation of ground based observations from satellite data MODIS and AERONET. Objective of the study was to map the spatial extent of fog as well as monitor its causes and similarly, to analyse fog days’ frequency, to analyse the Aerosol Optical Depth (AOD) over South Asia with particular focus over Indo Gangetic Plans (IGP). Smoke and absorbing aerosol are major constituent of fog over south Asia. Furthermore, winter 2014-15 extended span of Fog was also observed over South Asia. A significant correlation between MODIS (AOD) and AERONET Station (AOD) data was identified. Least number of dense fog days were observed during the recent winter (2015-2016) as compared to previous winters and may be attributed to onset El Nino conditions. Temperature and Precipitation Anomaly is depicting an overall warming effect over study region which further supports our speculation about least number of fog days during winter (2015-2016)..