Executive Summary : | The Eastern Himalayan Foothills region (EHF), comprising of the North East Indian states and adjoining areas (20°N-30°N and 86°E -100°E), is crucial in terms of atmospheric chemistry and its implications on climate change and vulnerability. The atmospheric composition of the region is found to be altered under the influence of dust advection from the Indian deserts through westerlies, anthropogenic emissions from the Indo Gangetic Plains (IGP), marine emissions from the Bay of Bengal, and local biogenic emissions from large vegetation cover, including primary and secondary bioaerosols as well as local anthropogenic emissions (e.g., biomass burning, fossil fuel burning, oil and gas fields, etc.). The region has been explored for the Spatio-temporal distribution of trace gases (O3, CO, NOx, SO2, VOCs, CH4) for a short period of time (1-4 years), except for CH4. Similarly, aerosols studies involve - aerosol radiation interaction (ARI), aerosol-cloud interaction (ACI), elevated aerosol layers. Both columnar aerosol loading and O3 in the region stand second highest in South Asia next to the Indo-Gangetic Plain, the surface level concentrations are also being appreciable. The increasing air pollution has threatened the climate, natural resources (water and forest), and biodiversity of the region. Landslides at hilly regions, lightning, and earthquakes are frequently occurring natural hazards of the region. Floods, flash floods, river-bank erosion are other frequent water-induced natural hazards in the Brahmaputra basin in Assam. Climate change is one of the driving forces in this changing hydrological cycle, triggering alteration in the regional and local weather system and as a consequence, affect the agricultural productivity over the region. However, a systematic and comprehensive approach to studying the climate change-hydrology-agriculture interaction in this region is still lacking. As such, the present proposal aims to explore the alteration of the atmospheric compositions over the last decades through a synergistic approach by using ground-based and satellite observation, reanalysis data, and WRF-Chem 3.8, RegCM 5 regional climate model simulations. This will assist to delineate the anthropogenic influence on climate change over the region, for example, anthropogenic emission driven observed continued increasing/decreasing seasonal temperature/rainfall pattern, at a longer time scale. The consequent implications on the hydrological cycle will be investigated using the RegCM5 model coupled with a hydrological model-Cetemps Hydrological (CHyM) by the projection of river discharge. Further, Climate change impact on agricultural productivity will be assessed through sensitivity analyses using the RegCM5 model. This study is expected to fill up the existing gap between climate change and its causative mechanisms, implications, and mitigation strategy, which in turn is associated with the livelihood and wellbeing of people of this part of the globe. |