A015-06
Quantification of regional methane emissions in Australia to inform and validate long-term climate policy

Monday, 7 December 2020: 05:45
Virtual
Dimitri Lafleur1, Jeremy Silver2, Steven P. Thomas3, Peter J Rayner4, Cathy M Trudinger5, Ashok Luhar6 and David M Etheridge5, (1)Postdoctoral fellow, CSIRO Oceans and Atmosphere, Aspendale, VIC, Australia, (2)The University of Melbourne, Melbourne, Australia, (3)University of Melbourne, Parkville, VIC, Australia, (4)The University of Melbourne, Parkville, Australia, (5)CSIRO, Oceans and Atmosphere, Aspendale, VIC, Australia, (6)CSIRO Ocean and Atmosphere Flagship Canberra, Yarralumla, Australia
Abstract:
Methane emissions from the Surat Basin, Queensland, Australia, originate from a mixture of anthropogenic and natural activities, including agriculture, coal mining and gas extraction. Over the last decade the area has seen a very large increase in unconventional gas extraction from coal seams, and it is not clear how this increased activity is affecting methane emissions on a regional and national scale.

Emissions are recorded in the national inventory using predominantly emission factors. Regional Inverse models using atmospheric methane observations can validate and improve such inventories and will be reliable tools for policy makers to reduce uncertainties of national inventory submissions to adhere to the Paris Climate Agreement and to successfully rachet up emission reductions.

We use a Bayesian regional inverse modelling approach to quantify methane emissions from the Surat Basin and to ascertain their source and location. A coupled WRF-CMAQ model setup is used to quantify transport of methane in the atmosphere, required for the inverse approach. The atmospheric methane observations come from two monitoring stations, outside of the main coal seam gas belt, along the axis of prevailing winds and are used to infer the emissions. A high-resolution regional emission inventory is used as a prior.

Preliminary results show that the WRF-CMAQ model confirms results from an earlier campaign of the region that used a coupled meteorological dispersion model. An advantage of the new model is that it will be able to use time varying data sources such as satellite and mobile device data. The new model also shows that continuous in-situ measurements are an important prerequisite for uncertainty reduction in the model and are a powerful tool to reduce uncertainty of long-term policy advice.

Regional inversions are a powerful tool for countries to validate emissions reduction efforts, to monitor their emissions on a continuous basis and to underpin long term policy choices.

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