Surface Observation Constrained High Frequency Coal Mine Methane Emissions in Shanxi China Reveal More Emissions than Inventories, Consistency with Satellite Inversion

Abstract

Abstract. This work focuses on Changzhi, Shanxi China, a city and surrounding rural region with one of the highest atmospheric concentrations of methane (CH₄) world-wide (campaign-wide minimum/mean/standard deviation/max observations: 2.0, 2.9, 1.3, and 16 ppm) due to a rapid increase in the mining, production, and use of coal over the past decade. An intensive 15-day surface observation campaign of CH₄ is used to drive a new analytical, mass-conserving method to compute and attribute CH₄ emissions. Observations made in concentric circles at 1 km, 3 km, and 5 km around a high production high gas coal mine yielded emissions of 0.73, 0.28, and 0.15 ppm min^-1 respectively. Attribution used a 2-box mass conserving model to identify the known mine’s emissions from 0.042–5.3 ppm min^-1, and a previously unidentified mine’s emission from 0.22–7.9 ppm min^-1. These results demonstrate the importance of simultaneously quantifying both the spatial and temporal distribution of CH₄ to better control regional-scale CH₄ emissions. Results of the attribution are used in tandem with observations of boundary layer height to quantify policy-relevant emissions from the two coal mines as 13670±7400 kg h^-1 and 5070±2270 kg h^-1 respectively. Both mines display a fat tail distribution, with respective 25^th, median, and 75^th percentile values of [870, 7500, 38700] kg h^-1 and [431, 1590, 7000] kg h^-1. These findings are demonstrated to be higher than CH₄ emissions from equivalent oil and gas operations in the USA, with one about double and the other similar to day-to-day emissions inverted over 5-years using TROPOMI over the same region.