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CNN's April 30, 2022 Planet-warming emissions from cow burps have been seen from space begins:

The emissions were detected by environmental data company GHGSat's high-resolution satellites in February, according to a news release from the company. In April the company's analysis confirmed that the emissions came from a cattle feedlot in California's Joaquin Valley.

The satellites recorded five emissions, says GHGSat. If these emissions were sustained for just one year, enough gas would be released "to power 15,402 homes," the company said.

Methane emissions from cattle have been identified as a significant contributor to climate change. As cows digest their food, they release methane, mostly through their gassy burps. But the methane they burp up is a powerful greenhouse gas that traps heat in the atmosphere. The Food and Agriculture Organization (FAO) says that farm cattle contribute to 10% of greenhouse gas emissions worldwide generated by human activity.

And cattle farming is a major industry in California: The state has 650,000 beef cows as of 2019, according to the California Cattlemen's Association.

Brody Wight, the sales director at GHGSat, told CNN this is the first time the company knows of in which scientists were able to use satellite imagery to pinpoint methane emissions from cattle farming. The company has three high-resolution satellites in orbit, which it has previously used to measure emissions from open-pit coal mines. Each satellite is just the size of a microwave oven, says GHGSat.

Question: What are the three high-resolution imaging satellites that GHGSat uses to make high spatial resolution images of methane emission (in this case, likely a cluster of cow burps) and how do these satellites image column-averaged ppb levels of methane above background? What kind of camera and wavelengths are used?

Graphic from the CNN article, showing column-average values of 20 to 100 ppb CH4 with an apparent spatial resolution of roughly tens of meters:

enter image description here

An environmental data company captured images of methane emissions from cattle taken from space.

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A quick online search shows the GHGSat web page discussing the satellites and their capabilities (emphasis mine):

GHGSat's vision is to become the global reference for the remote sensing of greenhouse gas (GHG) emissions from any source in the world. No other commercial or government satellite mission is specifically designed for detecting and quantifying GHG emissions from point sources as small as individual oil and gas wells.

The GHGSat constellation currently consists of three satellites, GHGSat-D (Claire) launched in June 2016, GHGSat-C1 (Iris) launched in September 2020, and GHGSat-C2 (Hugo) launched in January 2021.

Each satellite is equipped with a wide-angle Fabry-Perot (WAF-P) imaging spectrometer designed to measure the vertical column abundances of greenhouse gases. GHGSat-D is capable of measuring both methane and carbon dioxide, while GHGSat-C1 and GHGSat-C2 are optimised for methane.

The instrumentation carried and procedure is discussed further down the page.

The primary sensor on all GHGSat satellites is a Wide-Angle Fabry-Perot (WAF-P) Imaging Spectrometer. This primary sensor produces a hypercube consisting of a stack of overlapping, spectrally selected images acquired within <30 seconds. This hypercube embeds, for each ground pixel, information equivalent to hundreds of wavelengths from the top-of-the-atmosphere spectral radiance. Once downloaded, the hypercube is corrected for sensor response and instrument optics. The gas column density and surface reflectance information are then retrieved for each ground pixel using a measurement model which includes surface, instrument and atmospheric contributions to radiance. The resulting arrays are georeferenced, giving the "Surface Reflectance Image" and one "Abundance Dataset" for methane.

GHGSat satellites typically have a spatial resolution of 25 m (>50 m for GHGSat-D) and the Field of View (FOV) of approximately 12 km x 12 km of these datasets allow gas plumes emitted from industrial sources to be captured and distinguished from the surrounding background concentrations, constituting a differential measurement.

The particular details concerning the operating ranges of the spectrometer mentioned are listed as

SWIR 1630-1675 nm, multiple bands in a proprietary configuration, unpolarized

From Celestrak's satcat:

  • GHGSat-D: 2016-040D, 41602
  • GHGSAT-C1: 2020-061G, 46278
  • GHGSAT-C2: 2021-006DA, 47509
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  • $\begingroup$ The linked website also gives further details on how emissions "per ground pixel" are measured, and states a spatial resolution of 25 meters, in line with what the question suggests. $\endgroup$
    – njuffa
    May 1, 2022 at 20:25
  • $\begingroup$ Thank you for your post! The problems with saying that part of the answer can be found in a link include that if the link breaks or is changed the answer is no longer helpful in that regard, and that every user has to go offsite to find out that part of the answer. Can you add at least something minimal here that directly addresses "What kind of camera and wavelengths are used?" Thanks! $\endgroup$
    – uhoh
    May 1, 2022 at 22:34

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