11 Oct 2022
11 Oct 2022
Status: this preprint is currently under review for the journal AMT.

A new algorithm to generate a priori trace gas profiles for the GGG2020 retrieval algorithm

Joshua L. Laughner1, Sébastien Roche2,*, Matthäus Kiel1, Geoffrey C. Toon1, Debra Wunch2, Bianca C. Baier3,4, Sébastien Biraud5, Huilin Chen6, Rigel Kivi7, Thomas Laemmel8,**, Kathryn McKain3,4, Pierre-Yves Quéhé9, Constantina Rousogenous9, Britton B. Stephens10, Kaley Walker2, and Paul O. Wennberg11,12 Joshua L. Laughner et al.
  • 1Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
  • 2Department of Physics, University of Toronto, Toronto, Canada
  • 3Global Monitoring Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO, USA
  • 4Cooperative Institute for Research in Environmental Sciences, University of Colorado - Boulder, Boulder, CO, USA
  • 5Lawrence Berkeley National Laboratory, Berkeley, CA, USA
  • 6Center for Isotope Research, University of Groningen, Groningen, the Netherlands
  • 7Space and Earth Observation Centre, Finnish Meteorological Institute, Sodankylä, Finland
  • 8Laboratoire des Sciences du Climat et de l’Environnement (LSCE/IPSL), UMR CEA-CNRS-UVSQ, Gif-sur-Yvette, France
  • 9Climate and Atmosphere Research Centre (CARE-C), The Cyprus Institute, Nicosia, Cyprus
  • 10Earth Observing Laboratory, National Center for Atmospheric Research (NCAR), Boulder, CO, USA
  • 11Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA
  • 12Division of Engineering and Applied Science, California Institute of Technology, Pasadena, CA, USA
  • *now at: School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
  • **now at: Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Bern, Switzerland

Abstract. Optimal estimation retrievals of trace gas total columns require prior vertical profiles of the gases retrieved to drive the forward model and ensure the retrieval problem is mathematically well-posed. For well-mixed gases, it is possible to derive accurate prior profiles using an algorithm that accounts for general patterns of atmospheric transport coupled with measured time series of the gases in questions. Here we describe the algorithm used to generate the prior profiles for GGG2020, a new version of the GGG retrieval that is used to analyze spectra from solar-viewing Fourier transform spectrometers, including the Total Carbon Column Observing Network (TCCON). A particular focus of this work is improving the description of CO2, CH4, N2O, HF, and CO in the stratosphere. We show that the revised priors agree well with independent in situ and space-based measurements and improve the total column retrievals.

Joshua L. Laughner 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 amt-2022-267', Anonymous Referee #2, 08 Nov 2022
  • RC2: 'Comment on amt-2022-267', Anonymous Referee #1, 15 Nov 2022

Joshua L. Laughner et al.

Model code and software

Ginput: GGG meteorology and a priori VMR preprocessor Joshua Laughner and Sébastien Roche

Joshua L. Laughner et al.


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Short summary
Observations using sunlight to measure surface-to-space total column of greenhouse gases in the atmosphere need an initial guess of the vertical distribution of those gases to start from. We have developed an approach to provide those initial guess profiles that uses readily available meteorological data as input. This lets us make these guesses without simulating them with a global model. The profiles generated this way match independent observations well.