10th International Aerosol Conference
September 2 - September 7, 2018
America's Center Convention Complex
St. Louis, Missouri, USA

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Long Term Satellite Based Study on Aerosol and Trace Gases over the Capital City of Assam, Guwahati

JHUMA BISWAS, Papori Dahutia, Pandu College, Guwahati, Assam, India

     Abstract Number: 499
     Working Group: Remote/Regional Atmospheric Aerosol

Abstract
The variability and trend in aerosol optical depth (AOD) by using the Moderate Resolution Imaging Spectroradiometer (MODIS) level 3 Collection 6 data at 550 nm for the period January, 2004 to December, 2016 and tropospheric columns of nitrogen dioxide (NO2) and sulfur dioxide (SO2) data by using Ozone Monitoring Instrument (OMI) has been studied for the period October, 2004 to December, 2016 over capital city of Assam, Guwahati. The monthly average AOD value varies from its highest value (0.63±0.09) in March to its lowest value (0.23±0.05) in October for the study period over Guwahati. The seasonally averaged AOD reached its maximum in pre-monsoon (0.61 ± 0.06), followed by winter (0.47 ± 0.07) and monsoon (0.41 ± 0.04), with the minimum occurring in post-monsoon (0.25 ± 0.06) season. The observed Ångström exponent value varies from its minimum value (1.18 ± 0.05) in monsoon season to its maximum value (1.35 ± 0.09) in post-monsoon season. Considerable long-term annual increasing trends in AOD, Ångström exponent and tropospheric NO2 column has been observed over the study location. An increasing trend of total number of vehicles along with their emissions degrades the air quality and thereby contributing to the increasing trend of AOD over Guwahati. A significant correlation between long term averaged MODIS AOD and OMI NO2 tropospheric columns with same seasonality indicating their same source of origination. Long term increasing trend in Ångström exponents (~0.008 per year) signify the contribution of smaller size aerosols attributed to urbanization and human activity over Guwahati. The monthly average visibility in Guwahati is highest (27.5 km) in October with a moderate reduction observed during the monsoon, reaching a minimum of 7.2 km in March. With increasing AOD values, horizontal visibility decreases over Guwahati.