Atmospheric Environment 40 (2006) 2995–3007 A GIS based methodology for gridding of large-scale emission inventories: Application to carbon-monoxide emissions over Indian region Mohit Dalvi a,Ã , Gufran Beig b , Uday Patil c , Akshara Kaginalkar a , C. Sharma d , A.P. Mitra d a Centre for Development of Advanced Computing, Pune University Campus, Pune 411007, India b Indian Institute of Tropical Meteorology, Dr. Homi Bhabha Road, Pashan, Pune 411008, India c Department of Animal Husbandry, Government of Maharashtra, SB Road, Pune 411016, India d National Physical Laboratory, Dr. K.S. Krishnan Marg, New Delhi 110012, India Received 6 October 2004; received in revised form 13 July 2005; accepted 31 October 2005 Abstract Chemical simulations in most of the atmospheric chemistry models require surface emissions in a specific form (gridded), which are often not available. Simple interpolation of broader level emissions to obtain gridded data may lead to erroneous results. An attempt has been made in this paper to develop a geographical information system (GIS) based methodology for distributing the emissions from a broader level inventory to finely gridded emission values, considering local micro-level details and activity data. Given the importance of Carbon Monoxide emissions in ozone pollution chemistry over India, an emission inventory for CO from various sources for India has been used to demonstrate the GIS-based gridding methodology. The total CO emissions over India for 2001, which are estimated to be around 69.0 Tg year 1 , have been downscaled source-wise (distinguishing between rural and urban bio-fuel, vehicular traffic, coal and biomass burning) from state-level (28 points) to district level (500 points) before mapping through a GIS utility and finally gridded to a 11  11 resolution with a data loss of only about 13%. The final results provide detailed information with emission ‘‘hot spots’’ and the relative contribution of various sources. This article focuses on usage of the GIS based statistical methodology for gridding the inventory and the results obtained thereof are discussed. r 2006 Elsevier Ltd. All rights reserved. Keywords: Carbon monoxide; Indian inventory; Geographical information systems; Spatial distribution; Gridded emissions 1. Introduction It is increasingly obvious on the basis of various records that human activities over the last few decades have changed the chemical composition of the global atmosphere. Industrial emissions, inten- sification of agricultural practices, urban develop- ment and transportation have directly enhanced the levels of pollutant gases (viz. CO 2 ,N 2 O, CH 4 , CFCs, CO, NO x , SO 2 , VOCs, etc.) and aerosols, which are likely to have serious climatic implica- tions both directly through perturbations of the ARTICLE IN PRESS www.elsevier.com/locate/atmosenv 1352-2310/$ - see front matter r 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.atmosenv.2006.01.013 Ã Corresponding author. Tel.: +91 20 25704226; fax: +91 20 25694059. E-mail address: mohitd@cdac.in (M. Dalvi).