RECENT FIELD STUDIES HAVE DOCUMENTED A SURPRISINGLY STRONG AND CONSISTENT METHANE SINK IN ARCTIC MINERAL SOILS. IT HAS PREVIOUSLY BEEN ASSUMED THE ARCTIC REGION COULD ONLY BE A NET SOURCE OF METHANE. THIS OVERLOOKED METHANE SINK IS THOUGHT TO BE DUE TO A NOVEL METHANE OXIDIZING BACTERIA HIGH AFFINITY METHANOTROPH (HAM) THAT CAN SURVIVE AND OXIDIZE METHANE AT ATMOSPHERIC METHANE CONCENTRATIONS. HOWEVER THE DISTINCTIVE PHYSIOLOGY OF HAM HAS NOT BEEN REPRESENTED IN CURRENT REGIONAL METHANE SIMULATIONS. THUS WE PROPOSE TO INCORPORATE A SITE-LEVEL HAM MODEL INTO A METHANE BIOGEOCHEMISTRY MODEL TO QUANTIFY THE NET REGIONAL METHANE BUDGET. WE WILL CONDUCT A SET OF SIMULATIONS WITH VARIOUS COMPLEXITIES OF SOIL METHANE CONSUMPTION AND EMISSION ALGORITHMS. THESE SIMULATIONS WILL BE FED TO AN ATMOSPHERIC TRANSPORT CHEMISTRY MODEL AND COMPARED WITH IN SITU DATA FOR MODEL OPTIMIZATION. TO FURTHER CONSTRAIN ARCTIC SURFACE FLUXES WE WILL FEED THE MODEL SIMULATIONS TO THE ATMOSPHERIC TRANSPORT CHEMISTRY MODEL AS A PRIOR AND ASSIMILATE THE PRIOR SATELLITE AND IN-SITU OBSERVATIONS FOR ATMOSPHERIC INVERSIONS. POSTERIOR METHANE CONCENTRATIONS FOR ATMOSPHERIC INVERSIONS WILL BE EVALUATED USING AIRCRAFT DATA. THESE SIMULATIONS AND COMPARISONS WILL BE USED TO ASSESS THE IMPORTANCE OF HAM IN AFFECTING ATMOSPHERIC METHANE BUDGET. THE IMPROVED REGIONAL BIOGEOCHEMISTRY MODEL SHALL EVENTUALLY BE PART OF EARTH SYSTEM MODELS TO BE USED TO PROJECT OUR FUTURE CLIMATE. THIS STUDY WILL MAKE A SIGNIFICANT CONTRIBUTION TO NASA EARTH SCIENCE MISSIONS BY UTILIZING NASA UNIQUE CAPABILITIES TO DESIGN THE NEXT GENERATION PAN-ARCTIC METHANE MODEL.