Fluxes of Atmospheric Greenhouse-Gases in Maryland (FLAGG-MD): Emissions of Carbon Dioxide in the Baltimore-Washington, DC area
Doyeon Ahn, Jonathan R. Hansford, Shawn T. Howe, Xinrong R. Ren, Ross J. Salawitch, Ning Zeng, Mark D. Cohen, Barbara Stunder, Olivia E. Salmon, Paul B. Shepson, Kevin R. Gurney, Tomohiro Oda, Israel Lopez Coto, James R. Whetstone, Russel R. Dickerson
To study emissions of CO2 in the Baltimore-Washington, DC (Balt-Wash) area, an aircraft campaign was conducted in February 2015, as part of the FLAGG-MD (Fluxes of Atmospheric Greenhouse-Gases in Maryland) project. During the campaign, elevated mixing ratios of CO2 were observed downwind of the urban center and local power plants. Upwind flights data and HYSPLIT (Hybrid Single Particle Lagrangian Integrated Trajectory) model analyses help account for the impact of emissions outside the Balt-Wash area. The accuracy, precision, and sensitivity of CO2 emissions estimates based on the mass balance approach were assessed for both power plants and cities. Our estimates of two local power plants CO2 emissions agree well with their CEMS (Continuous Emissions Monitoring Systems) emissions records. For the 16 power plant plumes captured by aircraft, the mean percentage difference of CO2 emissions was − 0.3 %. For the Balt-Wash area as a whole, the 1𝜎 CO2 emission rate uncertainty for any individual aircraft-based mass balance approach experiment is ± 38 %. Treating the mass balance experiments, which were repeated 7 times within 9 days, as individual quantification of the Balt-Wash CO2 emissions, the estimation uncertainty in case of using the full dataset is ± 16 % (standard error of the mean at 95% CL). Our aircraft-based estimate was compared to various bottom-up fossil fuel CO2 (FFCO2) emission inventories. Based on the FLAGG-MD aircraft observations, we estimate 1.9±0.3 MtC of FFCO2 from the Balt-Wash area during February 2015. The mean estimate from the 4 bottom-up FFCO2 models was 2.2±0.3 MtC.