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Article Dans Une Revue Atmospheric Measurement Techniques Année : 2018

Improved retrievals of carbon dioxide from Orbiting Carbon Observatory-2 with the version 8 ACOS algorithm

Christopher O'Dell
  • Fonction : Auteur
Annmarie Eldering
Paul Wennberg
  • Fonction : Auteur
David Crisp
Michael Gunson
  • Fonction : Auteur
Brendan Fisher
  • Fonction : Auteur
Christian Frankenberg
Matthäus Kiel
  • Fonction : Auteur
Hannakaisa Lindqvist
  • Fonction : Auteur
Lukas Mandrake
  • Fonction : Auteur
Aronne Merrelli
  • Fonction : Auteur
Vijay Natraj
Robert Nelson
  • Fonction : Auteur
Gregory Osterman
  • Fonction : Auteur
Vivienne Payne
  • Fonction : Auteur
Thomas Taylor
  • Fonction : Auteur
Debra Wunch
Brian Drouin
  • Fonction : Auteur
Fabiano Oyafuso
Albert Chang
  • Fonction : Auteur
James Mcduffie
  • Fonction : Auteur
Michael Smyth
  • Fonction : Auteur
David Baker
Sourish Basu
Sean Crowell
Liang Feng
  • Fonction : Auteur
Paul Palmer
Mavendra Dubey
  • Fonction : Auteur
Omaira García
David Griffith
Frank Hase
  • Fonction : Auteur
Laura Iraci
Rigel Kivi
Isamu Morino
Justus Notholt
Hirofumi Ohyama
Christof Petri
Coleen Roehl
Mahesh Sha
Kimberly Strong
Ralf Sussmann
  • Fonction : Auteur
Yao Te
  • Fonction : Auteur
Osamu Uchino
  • Fonction : Auteur
Voltaire Velazco

Résumé

Since September 2014, NASA's Orbiting Carbon Observatory-2 (OCO-2) satellite has been taking measurements of reflected solar spectra and using them to infer atmospheric carbon dioxide levels. This work provides details of the OCO-2 retrieval algorithm, versions 7 and 8, used to derive the column-averaged dry air mole fraction of atmospheric CO 2 (X CO 2) for the roughly 100 000 cloud-free measurements recorded by OCO-2 each day. The algorithm is based on the Atmospheric Carbon Observations from Space (ACOS) algorithm which has been applied to observations from the Greenhouse Gases Observing SATellite (GOSAT) since 2009, with modifications necessary for OCO-2. Because high accuracy, better than 0.25 %, is required in order to accurately infer carbon sources and sinks from X CO 2 , significant errors and regional-scale biases in the measurements must be minimized. We discuss efforts to filter out poor-quality measurements, and correct the remaining good-quality measurements to minimize regional-scale biases. Updates to the radiance calibration and retrieval forward model in version 8 have improved many aspects of the retrieved data products. The version 8 data appear to have reduced regional-scale biases overall, and demonstrate a clear improvement over the version 7 data. In particular, error variance with respect to TCCON was reduced by 20 % over land and 40 % over ocean between versions 7 and 8, and nadir and glint observations over land are now more consistent. While this paper documents the significant improvements in the ACOS algorithm, it will continue to evolve and improve as the CO 2 data record continues to expand.
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Dates et versions

hal-02950533 , version 1 (08-10-2020)

Identifiants

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Christopher O'Dell, Annmarie Eldering, Paul Wennberg, David Crisp, Michael Gunson, et al.. Improved retrievals of carbon dioxide from Orbiting Carbon Observatory-2 with the version 8 ACOS algorithm. Atmospheric Measurement Techniques, 2018, 11 (12), pp.6539-6576. ⟨10.5194/AMT-11-6539-2018⟩. ⟨hal-02950533⟩
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