The GHGSat Aircraft Instrument: First Measurements and the Methane Plume Shadow Effect
Abstract
We present first results from GHGSat's aircraft instrument, GHGSat-AV that has been developed to complement GHGSat's satellite fleet with targeted, higher spatial resolution CH4 column density measurements. Whereas GHGSat satellite instruments have spatial resolutions of ~30 m from low Earth orbit, GHGSat-AV has a spatial resolution of < 1 m at 10,000 ft. GHGSat-AV can operate from a range of altitudes, trading area coverage for detection threshold. GHGSat-AV is designed to detect up to 90% of methane emissions by volume in shale plays.
GHGSat-AV is based on the same wide-angle Fabry-Perot (WAF-P) spectrometer concept used in GHGSat's satellite instruments: GHGSat-D (launched in 2016); GHGSat-C1 (planned launch date Aug 2020); and GHGSat-C2 (planned launch date Dec 2020). The ability to conduct measurements on similar platforms using common data processing and retrieval techniques - yet on spatial scales that differ by 50x - allows us to efficiently quantify CH4 emissions from industrial facilities using the optimal spatial resolution and detection sensitivity. We describe the GHGSat-AV design and measurement concept, including details about how the aircraft instrument differs from the satellite instruments. We present measurements of CH4 emissions from an unblinded controlled release test campaign conducted in Alberta, Canada in February/March 2020 and present initial source rate quantification results. We also show first evidence (to our knowledge) of a "plume shadow" effect in which the CH4 plume is resolved into two apparent plumes due to separate absorption from the downwelling and upwelling light paths. This additional information allows for the tomographic reconstruction of the plume's altitude and, possibly, its three-dimensional CH4 density distribution. We present a first analysis of this effect and suggest possible uses for this heretofore unexplored signal.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMGC0850021J
- Keywords:
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- 1610 Atmosphere;
- GLOBAL CHANGE;
- 1631 Land/atmosphere interactions;
- GLOBAL CHANGE;
- 1694 Instruments and techniques;
- GLOBAL CHANGE;
- 1875 Vadose zone;
- HYDROLOGY