28 Jul 2023
 | 28 Jul 2023

Performance and sensitivity of column-wise and pixel-wise methane retrievals for imaging spectrometers

Alana Ayasse, Daniel Cusworth, Kelly O'Neill, Justin Fisk, Andrew Thorpe, and Riley Duren

Abstract. Strong methane point source emissions generate large atmospheric concentrations that can be detected and quantified with infrared remote sensing and retrieval algorithms. Two standard and widely used retrieval algorithms for one class of observing platform, imaging spectrometers, include pixel-wise and column-wise approaches. In this study, we assess the performance of both approaches using the airborne imaging spectrometer (Global Airborne Observatory) observations of two extensive controlled release experiments. We find that the column-wise retrieval algorithm is sensitive to the flight line length and can have a systematic low bias with short flight lines, which is not present in the pixel-wise retrieval algorithm. However, when the flight line length is sufficiently long, the column-wise retrieval algorithms produce results that very closely match metered emission rates. Lastly, this study examines the methane plume detection performance of GAO with a column-wise retrieval algorithm, and finds minimum detection limits between 9–10 kg/hr and 90 % probability of detection between 10–45 kg/h. These results present a framework of rules for guiding proper concentration retrieval selection given conditions at the time of observation to ensure robust detection and quantification.

Alana Ayasse 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 egusphere-2023-1420', Anonymous Referee #1, 15 Sep 2023
  • RC2: 'Comment on egusphere-2023-1420', Anonymous Referee #2, 24 Sep 2023

Alana Ayasse et al.


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Short summary
Methane is a powerful greenhouse gas and a significant portion of methane comes from large individual plumes. Recently, airplane mounted infrared technologies have proven very good at detecting and quantifying these plumes. In order to extract the methane signal from the infrared image there are two widely used approaches, in this study we assess the performance of both approaches using controlled release experiments. We also examine the minimum detection limit of the infrared technology.