ARL Weekly News – Jan 7, 2021
New York City greenhouse gas emissions estimated within inverse modelling of aircraft measurements
Pitt, J.R., I. Lopez-Coto, K.D. Hajny, J. Tomin, R. Kaeser, T. Jayarathne, B.H. Tirm, C.R. Floerchinger, C.P. Loughner, C.K. Gately, L.R. Hutyra, K.R. Gurney, G.S. Roest, J. Liang, S. Gourdji, A. Karion, J.R. Whetstone, and P.B. Shepson (2021), New York City greenhouse gas emissions estimated within inverse modelling of aircraft measurements, Elementa: Science of the Anthropocene.
Abstract: Cities are greenhouse gas emission hotspots, making them targets for emission reduction policies. Effective emission reduction policies must be supported by accurate and transparent emissions accounting. Top-down approaches to emissions estimation, based on atmospheric greenhouse gas measurements, are an important and complementary tool to assess, improve and update the emission inventories on which policy decisions are based and assessed.
In this study we present results from nine research flights measuring CO2 and CH4 around New York City during the non-growing seasons of 2018 to 2020. We used an ensemble of dispersion model runs in a Bayesian inverse modelling framework to derive campaign-average posterior emission estimates for the New York-Newark, N.J. urban area of (125 ± 39) kmol CO2 s−1 and (0.62 ± 0.19) kmol CH4 s−1 (reported as mean ± 1σ variability across the nine flights). We also derived emission estimates of (45 ± 18) kmol CO2 s−1 and (0.20 ± 0.07) kmol CH4 s−1 for the five boroughs of New York City. These emission rates, among the first top-down estimates for New York City, are consistent with inventory estimates for CO2 but are 2.4 times larger than the gridded EPA CH4 inventory, consistent with previous work suggesting CH4 emissions from cities throughout the northeast U.S. are currently underestimated.