27 Sep 2023
 | 27 Sep 2023

Offshore methane detection and quantification from space using sun glint measurements with the GHGSat constellation

Jean-Philippe W. MacLean, Marianne Girard, Dylan Jervis, David Marshall, Jason McKeever, Mathias Strupler, Antoine Ramier, Ewan Tarrant, and David Young

Abstract. The ability to detect and quantify methane emissions from offshore platforms is of considerable interest to provide actionable feedback to industrial operators. While satellites offer a distinctive advantage for remote sensing of offshore platforms which may otherwise be difficult to reach, offshore measurements of methane from satellite instruments in the shortwave-infrared are challenging due to the low levels of diffuse sunlight reflected from water surfaces. Here, we use the GHGSat satellite constellation in a sun glint configuration to detect and quantify methane emissions from offshore targets around the world. We present a variety of examples of offshore methane plumes, including the largest single emission at (84,000 ± 24,000) kg h−1 observed by GHGSat from the Nord Stream 2 pipeline leak in 2022 and the smallest offshore emission measured from space at (180 ± 130) kg h−1 in the Gulf of Mexico. In addition, we provide an overview of the constellation’s offshore measurement capabilities. We measure a median column precision of 2.1% of the background methane column density and estimate a detection limit, from analytical modelling and orbital simulations, that varies between 160 kg h−1 and 600 kg h−1 depending on the latitude and season.

Jean-Philippe W. MacLean 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-2023-1772', Anonymous Referee #2, 16 Oct 2023
    • AC2: 'Reply on RC1', Jean-Philippe MacLean, 30 Nov 2023
  • RC2: 'Comment on egusphere-2023-1772', Anonymous Referee #3, 02 Nov 2023
    • AC1: 'Reply on RC2', Jean-Philippe MacLean, 30 Nov 2023
    • AC3: 'Reply on RC2', Jean-Philippe MacLean, 30 Nov 2023

Jean-Philippe W. MacLean et al.

Jean-Philippe W. MacLean et al.


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Short summary
We demonstrate the capabilities of the GHGSat satellite constellation to detect and quantify offshore methane emissions using a sun glint observation mode. Using this technique, we observe offshore methane emissions from space ranging from 180 kg/h to 84,000 kg/h. We further assess the instrument performance in offshore environments, both empirically and using analytical modelling, and find that the detection limit varies with latitude and season.