Atmospheric physical processes regulating diurnal and seasonal variations in CO2 fluxes over a large reservoir

Tuesday, 16 December 2014: 2:10 PM
Heping Liu1, Qianyu Zhang1, Gabriel George Katul2, Jonathan J Cole3 and Terry Chapin4, (1)Washington State University, Pullman, WA, United States, (2)Duke University, Durham, NC, United States, (3)Cary Institute of Ecosystem Studies, Millbrook, NY, United States, (4)University of Alaska Fairbanks, Fairbanks, AK, United States
As the role of carbon emissions from inland waters in regional and global carbon budget has become increasing apparent, better understanding the influence of environmental variables on CO2 exchange requires direct, long-term eddy covariance measurements of CO2 fluxes across the water-atmosphere interface. Here we provide analysis of CO2 fluxes over a large southern inland water body of Ross Barnett Reservoir in central Mississippi in 2008. It is found that greater atmospheric instability at night leads to approximately 70% greater CO2 effluxes than during daytime. Frequent synoptic weather events associated with extratropical cyclones induce CO2 flux pulses, resulting in further increase in annual CO2 effluxes by 16%. Therefore, our measurements indicate that CO2 emission rates from global inland waters, which do not account for the influence of these atmospheric physical processes on CO2 exchange across the water-air interface, are likely underestimated by approximately 42%. Field measurements and modeling efforts to estimate CO2 emissions should consider this daytime-nighttime efflux difference and the missing emissions during these synoptic weather events.