OBJECTIVES AND VISION OF THE ACTG BRANCH

The radiation balance of the earth-atmosphere system is controlled to a great extent by the interactions of solar/terrestrial radiation with atmospheric trace gases, in particular the green house gases and aerosols, the two minor components in the atmosphere. In addition, these species also adversely affect our living environment when their concentration crosses certain levels. Atmospheric aerosols affect the weather and climate directly through scattering or absorption of incoming solar radiation or outgoing terrestrial radiation and indirectly acting as cloud condensation nuclei. These both processes depend ultimately on their chemical composition and size characteristics, demanding information on size resolved chemical composition. The main objective of this branch is focused research on atmospheric trace gases like O3, NOx, CO, SO2 and GH gases (CO2, CH4, etc) and aerosol chemical composition along with their source/sink/distribution mechanisms and radiative and environmental impact with emphasis on Indian region. For this, the branch makes use of in-situ measurements at fixed locations and/or campaign mode field experiments, balloon-based measurements and satellite data along with modelling. The activity aims on the evolution of a 3D (latitude-longitude-altitude) picture of atmospheric trace gases and aerosols over Indian region and the surrounding oceanic regions with a view to understand their climatic and environmental Impacts. In view of the large spatio-temporal heterogeneity in the properties of trace gases and aerosols, the regional scale impacts of these species on Geosphere Biosphere System are to be addressed accounting the governing dynamical and photochemical processes.