Suresh Tiwari
Indian Institute of Tropical Meteorology, Pune, New Delhi Branch,. India

Assessment of carbonaceous aerosols over northern part of India: Mass level & its impact on regional climate

Time and place
Tuesday 2 February 2015, 11.15
Room C609, Arrhenius Laboratory, 6th floor


Carbonaceous aerosols (organic carbon, OC and black carbon/elemental carbon, BC/EC) which constitute a significant fraction (∼10–70%) of the fine aerosol mass (PM2.5) and have gain significant importance in aerosol research due to adverse effects on human health, environmental issues as visibility impairment, regional air pollution, etc. and climate change. The effects of these aerosols depend on particle size and chemical composition. In order to reduce the adverse impacts and to develop the mitigation strategies for air quality control, the knowledge of atmospheric aerosols and its chemical composition is very essential, especially over the developing countries in South Asia with the highest emissions. In view of the above importance, monitoring of mass PM, carbonaceous aerosols as well as it impact on regional climate were studied over northern part of India. The long term mass level of PM2.5 were recorded (~122 µgm-3 ) (annual mean) over Delhi which is around 10 times higher than the US-EPA standard (12 µgm-3), however, the BC mass concentrations were around  7 µgm-3 (annual mean) with the highest (>20 µgm-3) in the winter and lowest in the monsoon (~ 4 µgm-3). During the winter period, the contribution of OC was 7 times higher than the EC indicating significant influence of biomass and biofuel burning (burning of wood and agricultural waste). Radiative forcing due to aerosols and BC were studied and higher atmospheric heating rates up to 1.9-2.0 K day-1 was observed over Delhi. The BC DRF was found to be larger for air masses traversing north western India, Indus Basin and Punjab, which were identified via the concentrated weighted trajectory analysis as the carbonaceous aerosol hot-spot areas over the Indian subcontinent. Our study indicates that the policy level changes is required to mitigate the excess carbonaceous aerosol over this region which ranks among the highest in India and elsewhere especially during the post-monsoon and winter seasons.