Investigating model deficiencies in the global budget of ethane

Monday, 14 December 2015
Poster Hall (Moscone South)
Zitely Asafay Tzompa Sosa1, Christoph Andrea Keller2, Alexander J. Turner2, Emmanuel Mahieu3, Bruno Franco3 and Emily V Fischer1, (1)Colorado State University, Atmospheric Science, Fort Collins, CO, United States, (2)Harvard University, School of Engineering and Applied Sciences, Cambridge, MA, United States, (3)University of Liege, Liege (Sart Tilman), Belgium
Many locations in the Northern Hemisphere show a statistically-significant sharp increase in measurements of ethane (C2H6) since 2009. It is hypothesized that the recent massive growth of shale gas exploitation in North America could be the source of this change. However, state-of-the-science chemical transport models are currently unable to reproduce the hemispheric burden of C2H6 or the recent sharp increase, pointing to a potential problem with current emission inventories. To resolve this, we used space-borne CH4 observations from the Greenhouse Gases Observing SATellite (GOSAT) to derive C2H6 emissions. By using known emission ratios to CH4, we estimated emissions of C2H6 from oil and gas activities, biofuels, and biomass burning over North America. The GEOS-Chem global chemical transport model was used to simulate atmospheric abundances of C2H6 with the new emissions estimates. The model is able to reproduce Northern Hemisphere surface concentrations. However, the model significantly under-predicts the amount of C2H6 throughout the column and the observed Northern Hemispheric gradient as diagnosed by comparisons to aircraft observations from the Hiaper Pole-to-Pole (HIPPO) Campaign.