P20 Quantification of methane sources in the Barnett Shale (Texas) using the Penn State WRF-Chem-FDDA realtime modeling system

Lauvaux, T., A. Deng, B. Gaudet, Penn State University, C. Sweeney, G. Petron, A. Karion, Alan Brewer, Mike Hardesty, National Oceanic and Atmospheric Administration, Scott Herndon, Tara Yacovitch, Aerodyne Research, Inc., and Stephen Conley, University of California, Davis

Methane emissions from natural gas production areas are subject to large uncertainties at regional scales. Top-down methodologies offer an integrated approach to monitor these emissions but highly depend on the quality of the atmospheric model used to relate the surface emissions to the observed atmospheric concentrations. Using continuous measurements of in-situ CH4 mixing ratios from an intensive aircraft campaign over the Barnett Shale area in March 2013, we developed an atmospheric inversion system based on high resolution WRF simulations (1.33km) and a Lagrangian Particle Dispersion Model (LPDM) (Uliasz, 1995) to invert for the methane sources in the area. We present here the performance of the WRF-Chem-FDDA modeling system (Deng et al., 2012) using WMO surface stations, aircraft meteorological measurements (wind, temperature, humidity), and vertical profiles of the mean horizontal wind from a Doppler Lidar. We evaluated the impact of the additional aircraft and wind lidar data assimilated in WRF by using the concentration footprints along the different flight transects, and estimated the correlation between the locations of the footprints and the ethane-to-methane ratio of the sources. We finally discuss the modeling performance of our WRF-FDDA-LPDM system to distinguish the two major contributors to methane emissions in the area, i.e. from the urban area of Dallas-Fort Worth and from the Barnett shale gas activities.