Changes in long term CH4 fluxes from the Alaskan North Slope based on a sector analysis of Barrow CH4 mole fraction measurements

Thursday, 18 December 2014: 10:35 AM
Colm Sweeney1, Edward J Dlugokencky2, Steven C Wofsy3, Anna Karion1, Charles E Miller4, Steven J Dinardo5, Lori Bruhwiler6 and John B Miller7, (1)NOAA/Earth System Research Lab, Boulder, CO, United States, (2)NOAA, Boulder, CO, United States, (3)Harvard Univ, Cambridge, MA, United States, (4)Jet Propulsion Lab, Pasadena, CA, United States, (5)Jet Propulsion Laboratory, Pasadena, CA, United States, (6)NOAA/ESRL/GMD, Boulder, CO, United States, (7)NOAA/ESRL, Boulder, CO, United States
Large enhancements in CH4 over the north slope measured by the NASA Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE) aircraft have motivated a detailed sector analysis of CH4 mole fraction measured by NOAA's Baseline Observatory site at Barrow, AK since 1986. This analysis shows that there is a very strong seasonal cycle in the CH4 mole fraction when winds are coming from the southern sector, which peaks in August and September each year with average enhancements of ~80 ppb. Despite many suggestions from other recent studies that CH4 emissions should be significantly enhanced in this region, our analysis indicates that emissions from the North Slope have not increased since the start of the measurement record. However, large enhancements in the CH4 mole fraction originating from the North Slope are correlated with increases in the mean air temperature coming from the same air masses, suggesting that with continued increases in North Slope surface temperatures, CH4 emissions from permafrost will increase in the North Slope as predicted.