Preprints
https://doi.org/10.5194/amt-2020-513
https://doi.org/10.5194/amt-2020-513

  12 Jan 2021

12 Jan 2021

Review status: a revised version of this preprint was accepted for the journal AMT.

Spectral Calibration of the MethaneAIR Instrument

Carly Staebell1, Kang Sun1,2, Jenna Samra3, Jonathan Franklin4, Christopher Chan Miller3, Xiong Liu3, Eamon Conway3, Kelly Chance3, Scott Milligan5, and Steven Wofsy4,6 Carly Staebell et al.
  • 1Department of Civil, Structural and Environmental Engineering, University at Buffalo, Buffalo, NY, USA
  • 2Research and Education in Energy, Environment and Water Institute, University at Buffalo, Buffalo, NY, USA
  • 3Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, USA
  • 4School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
  • 5Headwall Photonics, Bolton, MA, USA
  • 6Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, USA

Abstract. MethaneAIR is the airborne simulator of MethaneSAT, an area-mapping satellite currently under development with the goal of locating and quantifying large anthropogenic point CH4 sources as well as diffuse basin-scale emissions. Built to closely replicate the forthcoming satellite, MethaneAIR consists of two imaging spectrometers. One detects CH4 and CO2 absorption around 1.65 and 1.61 μm, respectively, while the other constrains the optical path in the atmosphere by detecting O2 absorption near 1.27 μm. The high spectral resolution and stringent retrieval accuracy requirements of greenhouse gas remote sensing in this spectral range necessitate a reliable spectral calibration. To this end, on-ground laboratory measurements were used to derive the spectral calibration of MethaneAIR, serving as a pathfinder for the future calibration of MethaneSAT. Stray light was characterized and corrected through Fast Fourier Transform (FFT)-based Van Cittert deconvolution. Wavelength registration was examined and found to be best described by a linear relationship for both bands with a precision of ~0.02 spectral pixel. The instrument spectral spread function (ISSF), measured with fine wavelength steps of 0.005 nm near a series of central wavelengths across each band, was oversampled to construct the instrument spectral response function (ISRF) at each central wavelength and spatial pixel. The ISRFs were smoothed with a Savitzky-Golay filter for use in a lookup table in the retrieval algorithm. The MethaneAIR spectral calibration was evaluated through application to radiance spectra from an instrument flight over the Colorado Front Range.

Carly Staebell et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on amt-2020-513', Anonymous Referee #1, 20 Jan 2021
    • AC1: 'Reply on RC1', Carly Staebell, 01 Apr 2021
  • RC2: 'Comment on amt-2020-513', Anonymous Referee #2, 27 Jan 2021
    • AC2: 'Reply on RC2', Carly Staebell, 01 Apr 2021
  • RC3: 'Comment on amt-2020-513', Anonymous Referee #3, 12 Feb 2021
    • AC3: 'Reply on RC3', Carly Staebell, 01 Apr 2021
  • RC4: 'Comment on amt-2020-513', Anonymous Referee #4, 26 Feb 2021
    • AC4: 'Reply on RC4', Carly Staebell, 01 Apr 2021

Carly Staebell et al.

Carly Staebell et al.

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