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Title: Constraints on methane emissions in North America from future geostationary remote-sensing measurements

The success of future geostationary (GEO) satellite observation missions depends on our ability to design instruments that address their key scientific objectives. Here, an Observation System Simulation Experiment (OSSE) is performed to quantify the constraints on methane (CH 4) emissions in North America obtained from shortwave infrared (SWIR), thermal infrared (TIR), and multi-spectral (SWIR+TIR) measurements in geostationary orbit and from future SWIR low-Earth orbit (LEO) measurements. Furthermore, we used an efficient stochastic algorithm to compute the information content of the inverted emissions at high spatial resolution (0.5° × 0.7°) in a variational framework using the GEOS-Chem chemistry-transport model and its adjoint. Our results show that at sub-weekly timescales, SWIR measurements in GEO orbit can constrain about twice as many independent flux patterns than in LEO orbit, with a degree of freedom for signal (DOF) for the inversion of 266 and 115, respectively. Comparisons between TIR GEO and SWIR LEO configurations reveal that poor boundary layer sensitivities for the TIR measurements cannot be compensated for by the high spatiotemporal sampling of a GEO orbit. The benefit of a multi-spectral instrument compared to current SWIR products in a GEO context is shown for sub-weekly timescale constraints, with an increase in the DOFmore » of about 50 % for a 3-day inversion. Our results further suggest that both the SWIR and multi-spectral measurements on GEO orbits could almost fully resolve CH 4 fluxes at a spatial resolution of at least 100 km × 100 km over source hotspots (emissions > 4 × 10 5 kg day -1). The sensitivity of the optimized emission scaling factors to typical errors in boundary and initial conditions can reach 30 and 50 % for the SWIR GEO or SWIR LEO configurations, respectively, while it is smaller than 5 % in the case of a multi-spectral GEO system. Our results demonstrate that multi-spectral measurements from a geostationary satellite platform would address the need for higher spatiotemporal constraints on CH 4 emissions while greatly mitigating the impact of inherent uncertainties in source inversion methods on the inferred fluxes.« less
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [2] ;  [3] ;  [3]
  1. Univ. of Colorado, Boulder, CO (United States). Dept. of Mechanical Engineering
  2. Harvard Univ., Cambridge, MA (United States). School of Engineering and Applied Sciences
  3. California Inst. of Technology (CalTech), Pasadena, CA (United States). Jet Propulsion Lab.
Publication Date:
Grant/Contract Number:
NNX14AH02G; NA14OAR4310136; CNS-0821794
Type:
Accepted Manuscript
Journal Name:
Atmospheric Chemistry and Physics (Online)
Additional Journal Information:
Journal Name: Atmospheric Chemistry and Physics (Online); Journal Volume: 16; Journal Issue: 10; Journal ID: ISSN 1680-7324
Publisher:
European Geosciences Union
Research Org:
Univ. of Colorado, Boulder, CO (United States). Dept. of Mechanical Engineering
Sponsoring Org:
USDOE; National Science Foundation (NSF); National Aeronautics and Space Administration (NASA)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES
OSTI Identifier:
1375408