Variability in aerosols properties and sources over rohtak, India

Abstract

Aerosols are crucial species in climate-related studies due to their significant impacts on radiative forcing. In the present study, Sky-radiometer POM-2 data was used to investigate the source of daily and monthly variability in aerosol properties over Rohtak city for the period from June, 2012-May, 2014. The annual mean values of AOD, Alpha, SSA and ASY were 0.71 ± 0.36, 0.74 ± 0.35, 0.93 ± 0.05 and 0.71 ± 0.02, respectively for the entire study period. The higher value of AOD and the lower value of Alpha during pre-monsoon months indicated the dominance of coarse mode dust particles. During November month, the lower value of SSA (0.84 ± 0.01) suggesting the dominance of absorbing type aerosol which may be associated with the burning of paddy crop residue and firecrackers on Diwali festival, in North-Western India. Another crucial parameter for the aerosol study in volume size distribution which exhibits a bimodal distribution with the first peak at ~0.20 µm for fine mode particles and a second peak at ~ 5 µm for coarse mode particles. Aerosols are classified into four categories by using the ratio of AOD and Alpha: Dust Dominated (DD), Biomass Burning (BB), Anthropogenic Aerosol (AA) and Mixed Type (MT). Dust dominated (DD) aerosols are found maximum during pre-monsoon and monsoon seasons with a fraction of about 26.4% and 19.8%, respectively. Biomass burning (BB) type aerosols are dominant during the post-monsoon and winter seasons with a fraction of 34% and 30%, respectively.