Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 18, 8265-8278, 2018
https://doi.org/10.5194/acp-18-8265-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
13 Jun 2018
Assessing the capability of different satellite observing configurations to resolve the distribution of methane emissions at kilometer scales
Alexander J. Turner1,2, Daniel J. Jacob2, Joshua Benmergui2, Jeremy Brandman3, Laurent White3, and Cynthia A. Randles3 1College of Chemistry/Department of Earth and Planetary Sciences, University of California, Berkeley, CA, USA
2School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
3ExxonMobil Research and Engineering Company, Annandale, NJ, USA
Abstract. Anthropogenic methane emissions originate from a large number of fine-scale and often transient point sources. Satellite observations of atmospheric methane columns are an attractive approach for monitoring these emissions but have limitations from instrument precision, pixel resolution, and measurement frequency. Dense observations will soon be available in both low-Earth and geostationary orbits, but the extent to which they can provide fine-scale information on methane sources has yet to be explored. Here we present an observation system simulation experiment (OSSE) to assess the capabilities of different satellite observing system configurations. We conduct a 1-week WRF-STILT simulation to generate methane column footprints at 1.3  ×  1.3 km2 spatial resolution and hourly temporal resolution over a 290  ×  235 km2 domain in the Barnett Shale, a major oil and gas field in Texas with a large number of point sources. We sub-sample these footprints to match the observing characteristics of the recently launched TROPOMI instrument (7  ×  7 km2 pixels, 11 ppb precision, daily frequency), the planned GeoCARB instrument (2.7  ×  3.0 km2 pixels, 4 ppb precision, nominal twice-daily frequency), and other proposed observing configurations. The information content of the various observing systems is evaluated using the Fisher information matrix and its eigenvalues. We find that a week of TROPOMI observations should provide information on temporally invariant emissions at  ∼  30 km spatial resolution. GeoCARB should provide information available on temporally invariant emissions  ∼  2–7 km spatial resolution depending on sampling frequency (hourly to daily). Improvements to the instrument precision yield greater increases in information content than improved sampling frequency. A precision better than 6 ppb is critical for GeoCARB to achieve fine resolution of emissions. Transient emissions would be missed with either TROPOMI or GeoCARB. An aspirational high-resolution geostationary instrument with 1.3  ×  1.3 km2 pixel resolution, hourly return time, and 1 ppb precision would effectively constrain the temporally invariant emissions in the Barnett Shale at the kilometer scale and provide some information on hourly variability of sources.
Citation: Turner, A. J., Jacob, D. J., Benmergui, J., Brandman, J., White, L., and Randles, C. A.: Assessing the capability of different satellite observing configurations to resolve the distribution of methane emissions at kilometer scales, Atmos. Chem. Phys., 18, 8265-8278, https://doi.org/10.5194/acp-18-8265-2018, 2018.
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Short summary
We conduct a 1-week WRF-STILT simulation to generate methane column footprints at 1.3 km spatial resolution and hourly temporal resolution over the Barnett Shale. We find that a week of TROPOMI observations should provide regional (~30 km) information on temporally invariant sources and GeoCARB should provide information on temporally invariant sources at 2–7 km spatial resolution. An instrument precision better than 6 ppb is an important threshold for achieving fine resolution of emissions.
We conduct a 1-week WRF-STILT simulation to generate methane column footprints at 1.3 km spatial...
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