XCH4 retrieval from MethaneAIR: An airborne precursor to the MethaneSAT mission
Christopher Chan Miller, Harvard-Smithsonian Center for Astrophysics, cmiller@fas.harvard.edu (Presenter)
Kang Sun, University of Bufallo, kangsun@buffalo.edu
Jenna Samra, Harvard-Smithsonian Center for Astrophysics, jsamra@cfa.harvard.edu
Jonathan Franklin, Harvard University, jfranklin@g.harvard.edu
Josh Benmergui, Harvard University, benmergui@g.harvard.edu
Peter Cheimets, Harvard-Smithsonian Center for Astrophysics, pcheimets@cfa.harvard.edu
Xiong Liu, Harvard-Smithsonian Center for Astrophysics, xliu@cfa.harvard.edu
Amir Souri, Harvard-Smithsonian Center for Astrophysics, ahsouri@cfa.harvard.edu
Yeonjin Jung, Harvard-Smithsonian Center for Astrophysics, yeonjin.jung@cfa.harvard.edu
Kelly Chance, Harvard-Smithsonian Center for Astrophysics, kchance@cfa.harvard.edu
Martin Ettenberg, Princeton Infrared Technologies, Inc., martin.ettenberg@princetonirtech.com
Scott Milligan, Headwall Photonics, Inc, smilligan@headwallphotonics.com
Ritesh Gautem, Environmental Defense Fund, rgautam@edf.org
Mark Omara, Environmental Defense Fund, momara@edf.org
Ju Chulakadabba, Harvard University, achulakadabba@g.harvard.edu
Yang Li, Texas A&M, yangli@seas.harvard.edu
Bruce Daube, Harvard University, bdaube@g.harvard.edu
Carly Staebel, University of Bufallo, carlysta@buffalo.edu
Eamon Conway, Harvard-Smithsonian Center for Astrophysics, eamon.conway@cfa.harvard.edu
Sara Mikaloff-Fletcher, National Institute of Water and Atmospheric Research, sara.mikaloff-fletcher@niwa.co.nz
Steven Hamburg, Environmental Defense Fund, shamburg@edf.org
Tom Ingersoll, Environmental Defense Fund, tingersoll@edf.org
Steven Wofsy, Harvard University, wofsy@g.harvard.edu
MethaneAIR is an aircraft-based pushbroom imaging spectrometer in support of MethaneSAT, a future satellite mission for launch in Q4 2022 commissioned by the EDF to quantify methane emissions primarily from global oil and gas production. MethaneAIR was built to match the specifications of the satellite, in order to serve as a testbed for prelaunch development and validation of MethaneSAT’s retrieval algorithms. Here we present methane total column (XCH4) observations from the two maiden flights of MethaneAIR over the Colorado front range from November 2019, using the MethaneSAT CO2-proxy retrieval algorithm.
An initial analysis of the MethaneAIR spectra revealed a drift in the instrument spectral response function (ISRF) for both flights. We present an automated procedure to track and correct for these drifts based on squeezing the pre-flight laboratory ISRF on sets of aggregated spectra. The ISRF drifts are strongly correlated with aircraft cabin temperature, indicating that they are likely caused by defocusing induced by changes in the optical bench temperature.
The first two flights were planned as a flat-field experiment: Analysis of data over homogeneous portions of the flight suggest a retrieval precision of ~15 ppbv for a 100x100 m^2 pixel. Although source detection was not prioritized during the flights, with flights targeting methane sources planned for later this summer over the Permian Basin, a plume originating from a landfill was detected on multiple flight passes. A number of intermittent plumes from local oil and gas infrastructure were also observed. Whilst the first flights have demonstrated the capability of the instrument to detect plumes from individual facilities, we discuss the additional challenges for detecting diffuse sources (enhancements of 4ppbv over 1 km length scales), and possible approaches for meeting these high precision targets, towards helping advance the goals of MethaneSAT to quantify area-aggregate methane emissions.
Poster: Poster_Chan_Miller__156_25.pdf
Presentation Type: Poster
Session: 1.5d Retrieval algorithms and methods for inter-instrument and product Cal/Val
Session Date: Monday (6/14) 12:00 PM