A Study on Characterization of Aerosol and Estimation of Direct Radiative Forcing Over Important Cities in Indo Gangetic Plain

Abstract

Aerosols have the potential to affect radiative forcing, cause climate change and alter the general atmospheric circulation patterns and biogeochemical cycle. However, assessing the aerosol impact on climate change is one of the most challenging issues in atmospheric science due to the complex non-linear interactions between aerosol, solar radiation, clouds, and precipitation. PM2.5 and BC are short lived climate forcer but their quantitative contribution to radiative forcing is least known particularly over the Indo-Gangetic basin which is one of the seven hot spots in the world. newlineThe present research study deals with the measurements and characterization of aerosol particles (PM10, PM2.5 and Black Carbon) mass concentration, aerosol optical properties obtained from ground/satellite observations and efficient estimations using a novel hybrid model (based on Genetic Algorithm and OPAC), and quantitative estimation of radiative forcing due to aerosol and due to black carbon alone for six prominent cities (viz.; Agra, Delhi, Hisar, Kanpur, Kolkata, and Varanasi) situated over the Indo-Gangetic plain. Chapter 1 dealt with understanding the problem and need of the study. Chapter 2 summarizes the work carried out in India and abroad in the concerned field. The methodology adopted to fulfil the objectives of the present investigation was discussed in Chapter 3. In Chapter 4, the results and outcome of the work have been evaluated. The concentration of PM10, and PM2.5 was higher at all the sites throughout the year and was found to be many folds higher than the standard set by WHO, USEPA, EUPAQs, China and India. None of the sites met the standards even set by our own country. BC concentration was high and showed the highest concentration in the post-monsoon or winter season. A hybrid model (genetic algorithm (GA) based technique and OPAC) has been developed to compute the optical properties of aerosol and the values obtained was in good agreement with ground and satellite based observation. Quantitative estimation of aerosol radiative forcing due to aerosol and due to BC alone revealed the significant contribution of black in radiative forcing over the Indo-Gangetic plain. newline newline newline