@ Photonirvachak Journal of the Indian Society of Remote Sensing, Vol 35, No. 4, 2007 METHANE EMISSION MODELLING USING MODIS THERMAL AND OPTICAL DATA: A CASE STUDY ON GUJARAT RESHU AGARWAL@ AND J.K. GARG Space Applications Center (ISRO), Ahmedabad-380015, India @Corresponding author : stat_reshu@yahoo.com ABSTRACT Wetlands are one of the most important sources of atmospheric methane (CIt4) contributing about 22% to the global methane budget. But to improve estimates of CH4 emission at regional and global scales there is a need to observe the sources such as wetlands frequently and develop process-based models. In this regard, wetland inventory using satellite remote sensing data has conventionally been carried out by analysis of optical data. Due to thermal inertia differences emittive thermal channels data has shown protmse to provide highly critical intbrmation about wetlands such as water spread, aquatic vegetation and mud flats etc. Thermal channels data of MODIS (Moderate Resolution Imaging Spectroradiometer) sensor with a spatial resolution of 1km and swath of 2330 km is emerging as the key source of remote sensing data for global/ regional wetland estimation and assessment of green house gas emission. In the present study MODIS thermal channels (31 and 32) and optical channels (1, 2, and 3) data have been used lbr evaluating methane emission from wetlands in Gujarat. An empirical model based on temperature and productivity has been used to investigate the response of methane emission from different sources Model has the potential to estimate country level methane emission based on salellite remote sensing in conjunction w~th collateral data/information In this study, MODIS data of two dates pertaining to Gujarat have been analyzed and results compared with respect to methane emission. Introduction Methane is considered as the most significant natural greenhouse gas due to its global warming potential. Methane has a large radiative effect with one unit mass of CH 4 producing 21 times the radiative effect of one unit mass of CO2 According to International Panel on Climate Change (IPCC, 1998) since 1750 atmospheric concentration of methane has increased by 150 per cent (as of 1998) from approximately 700 to 1,745 parts per billion by volume (ppbv). Wetlands are one of the most Recewed 17 Aprd, 2007, in final forn3 28 .lune, 2007