Hu Lei, Andrews Arlyn E, Montzka Stephen A, Miller Scot M, Bruhwiler Lori, Oh Youmi, Sweeney Colm, Miller John B, McKain Kathryn, Ibarra Espinosa Sergio, Davis Kenneth, Miles Natasha, Mountain Marikate, Lan Xin, Crotwell Andy, Madronich Monica, Mefford Thomas, Michel Sylvia, Houwelling Sander
Global Monitoring Laboratory, US National Oceanic and Atmospheric Administration, Boulder, Colorado 80305, United States.
Department of Environmental Health and Engineering, Johns Hopkins University, Baltimore, Maryland 21218, United States.
Environ Sci Technol. 2025 May 27;59(20):9968-9979. doi: 10.1021/acs.est.4c14090. Epub 2025 May 14.
Accurate quantification of methane (CH) emissions is essential for understanding changes in its atmospheric abundance. Atmospheric observations can supply independent emission information that complements and strengthens inventory-based estimates. In this study, we quantified annual and monthly U.S. CH emissions in 2008-2021 using inverse modeling of ground and airborne measurements at sites across the U.S. with 10-12 km atmospheric transport simulations. While the magnitude, spatial distribution, and trend of the estimated CH emissions align with some previous studies, our results reveal an unexpected seasonal cycle in CH emissions from the oil and gas sector, where wintertime emissions are about 40 (20-50, 2σ) % higher than summertime. This seasonality is supported by methane and propane measurements at these same sites, as well as methane isotope measurements made from an independent aircraft campaign over the U.S. Although the exact cause of this emission seasonality is unclear, its spatial distribution indicates that the enhanced CH emissions are primarily from natural gas production regions, and to a lesser extent, from natural gas consumption in winter.
准确量化甲烷（CH）排放对于了解其大气丰度变化至关重要。大气观测可以提供独立的排放信息，补充并强化基于清单的估算。在本研究中，我们利用美国各地站点的地面和机载测量数据进行反演建模，并结合10 - 12公里的大气传输模拟，对2008 - 2021年美国的年度和月度CH排放进行了量化。虽然估算的CH排放的量级、空间分布和趋势与之前的一些研究一致，但我们的结果揭示了石油和天然气行业CH排放中一个意外的季节性循环，即冬季排放量比夏季高出约40%（20 - 50，2σ）。这些相同站点的甲烷和丙烷测量结果，以及在美国上空进行的一次独立飞机测量活动所得到的甲烷同位素测量结果，都支持了这种季节性。尽管这种排放季节性的确切原因尚不清楚，但其空间分布表明，CH排放增加主要来自天然气生产地区，在较小程度上来自冬季的天然气消费。
