A Semi Automated Empirical Model for Estimation of Ch4 Emission Using Coarse Resolution Thermal Data

Concentration of atmospheric methane is considered to have a significant effect on climate because of its GWP (Global Warming Potential), which is 21 times of CO2. Methane is generated by the process of methanogenesis under wet anaerobic conditions, oxidation by methanotrophic bacteria and transportation to the atmosphere. Wetlands are the major source of methane emission, because of the presence of anoxic conditions, organic material content and large area. They contribute approximately 22% to the global methane budget. In addition to wetlands, landfills, rice paddies and termites etc. are the other major sources of methane emission. However, there is a high degree of uncertainty about the actual contribution of all these methane-emitting sources to the total methane budget. In the present study a Semi-automated Empirical Methane Emission Model (SEMEM) has been developed and used for estimation of methane from wetlands using MODIS (Moderate Resolution Imaging Spectroradiometer) data. Model has two key factors, namely, temperature and productivity. Productivity and fluxes have been taken from literature and used as inputs for different methane emitting sources. Area extent of different wetlands has been estimated based on knowledge-based classifier using NDVI, optical bands (1,2, 3) with thermal channel (31 and 32) data. As methanogenesis is a temperature dependent process, the model makes use of LST (Land Surface Temperature) which has been generated using Split Window Method (SWM) of first order approximation. A Semi-automated Empirical Methane Emission Model (SEMEM) has been developed for estimation of methane emission from wetlands. Based on the analysis of MODIS data, methane emission from wetlands has been estimated for India pertaining to the months of May 2005 and October 2005. Results shows that emitted methane in the month of May2005 was 10515 kg with 29419 sq.km total methane emitting area whereas in the month of Oct 2005 total emitted methane was 38069 kg with 93995 sq.km methane emitting area.