Forecasting of regional methane from coal mine emissions in the Upper Silesian Coal Basin using the on-line nested global regional chemistry climate model MECO(n)(MESSy v2.53)

Abstract. Methane is the second most important greenhouse gas in terms of anthropogenic radiative forcing. Since pre-industrial times, the globally averaged dry mole fraction of methane in the atmosphere has increased considerably. Emissions from coal mining are one of the primary anthropogenic methane sources. However, our knowledge about different sources and sinks of methane is still subject to great uncertainties. Comprehensive measuring campaigns, as well as reliable chemistry climate models, are required to fully understand the global methane budget and to further develop future climate mitigation strategies. The CoMet 1.0 campaign (May to June 2018) combined airborne in-situ, as well as passive and active remote sensing measurements to quantify the emissions from coal mining in the Upper Silesian Coal Basin (USCB, Poland). Roughly 502 kt of methane are emitted from the ventilation shafts per year. In order to help the campaigns flight planning, we performed 6-day forecasts using the on-line coupled, three times nested global and regional chemistry climate model MECO(n). We applied three nested COSMO/MESSy instances going down to a spatial resolution of 2.8 km over the USCB. The nested global/regional model system allows for the separation of local emission contributions from fluctuations in the background methane. Here we introduce the forecast setup and assess the model skill by comparing different observations with the individual forecast simulations. Results show that MECO(3) is able to simulate the observed methane plumes and the large scale patterns (including vertically integrated values) reasonably well. Furthermore we receive reasonable forecast results up to forecast day four.