Climate And Air Quality Impacts (Work Package-3)


Atmospheric carbonaceous aerosols significantly change the energy balance of Earth‘s surface and atmosphere, and alter cloud properties, thereby affecting climate. The response of South Asian monsoon rainfall to the different components of aerosol radiative forcing, i.e., the direct and indirect effect, is being debated in literature. Previous studies (Both Salzmann et al. 2014 and Guo et al. 2015) suggest that CMIP5 models which include aerosol forcing, are able to simulate drying rainfall trends over South Asia during 1950-2000, while Guo et al. (2015) further attribute this ability specifically to only models that parameterise aerosol indirect forcing. This suggests that accurate simulation of observed monsoon drying trend over parts of South Asia, might crucially depend upon representation of the aerosol indirect effect in models. The NCAP seeks to further our understanding of regional carbonaceous aerosols in terms of major sources and their influence, atmospheric transformations and processes, impact on clean air and climate and impact on vulnerable ecosystems like the Himalaya. The deposition of absorbing aerosol particles including black carbon and dust decreases reflectivity of snow and ice surfaces, causing radiative forcing which has high efficacy. There are many gaps in our understanding of carbonaceous aerosol emissions, properties and climate effects, which lead to climate change, particularly on regional scales.

To address the above challenges a multi-model (Global and regional models) inter-comparison study is being undertaken, over the South Asian domain, under the National Carbonaceous Aerosols Programme project on CarbOnaceous AerosoL Emissions, Source apportionment and ClimatE impacts(NCAP-COALESCE). As part of this effort, the proposed scientific hypothesis is to evaluate the response of South Asian monsoon precipitation response to aerosol direct and indirect radiative forcing using General Circulation Models (GCMs) & Regional Climate Models (RCMs). The overall scope of the inter-comparison study would also include evaluating ability of models to reproduce concentrations of aerosols and constituent species (BC, OC, sulphate), aerosol properties (AOD, SSA, extinction and asymmetry parameter) and processes like aerosol dry and wet deposition, in the South Asian region.

List of Participating GCM models

S. No.GCMInstitute
1ECHAM6-HAM2Indian Institute of Technology, Bombay
2CAM5Indian Institute of Technology, Delhi
(with modified optics)
Physical Research Laboratory, Ahmedabad
4HadGEM-ABritish Antarctic Survey, UK
5CESMCSIR Fourth Paradigm Institute, Bangalore
6NICAM- SPRINTARSBhabha Atomic Research Centre, Mumbai
7IITM ESMIndian Institute of Tropical Meteorology,Pune

List of Participating RCM models

S. No.RCMInstitute
1WRF-ChemIndian Institute of Technology, Bombay
(with different modelphysics)
National Atmospheric Research Laboratory, Gadanki
Indian Institute of Science Education & Research, Bhopal
3RegCMIndian Institute of Technology, Delhi
4WRF-CHIMEREIndian Institute of Technology, Kharagpur
5GEOS-ChemIndian Institute of Technology, Madras
(high resolution)
Columbia University, New York
7WRF-CMAQPune University
National Atmospheric Research Laboratory, Gadanki

Current Status

The recent Work Packet 3 (WP-3) workshop was held on 13th June 2018 at Indian Institute of Science Education and Research (IISER) – Bhopal. The WP-3 participating institutes has setup the respective models and aimed to complete the one year free run simulations by end of September 2018 and validated the model simulations with available observations.

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