Evaluation of MOPITT Version 7 joint TIR-NIR X<SUB>CO</SUB> retrievals with TCCON - INSU - Institut national des sciences de l'Univers Access content directly
Journal Articles Atmospheric Measurement Techniques Year : 2019

Evaluation of MOPITT Version 7 joint TIR-NIR XCO retrievals with TCCON

Jacob K. Hedelius
  • Function : Author
Tai-Long He
  • Function : Author
Dylan B. A. Jones
  • Function : Author
Bianca C. Baier
  • Function : Author
Rebecca R. Buchholz
  • Function : Author
Martine de Mazière
  • Function : Author
Nicholas M. Deutscher
  • Function : Author
Manvendra K. Dubey
  • Function : Author
Dietrich G. Feist
  • Function : Author
David W. T. Griffith
  • Function : Author
Frank Hase
  • Function : Author
Laura T. Iraci
  • Function : Author
Matthäus Kiel
  • Function : Author
Rigel Kivi
  • Function : Author
Cheng Liu
  • Function : Author
Isamu Morino
  • Function : Author
Justus Notholt
  • Function : Author
Young-Suk Oh
  • Function : Author
Hirofumi Ohyama
  • Function : Author
David F. Pollard
  • Function : Author
Markus Rettinger
  • Function : Author
Sébastien Roche
  • Function : Author
Coleen M. Roehl
  • Function : Author
Matthias Schneider
  • Function : Author
Kei Shiomi
  • Function : Author
Kimberly Strong
  • Function : Author
Ralf Sussmann
  • Function : Author
Colm Sweeney
  • Function : Author
Osamu Uchino
  • Function : Author
Voltaire A. Velazco
  • Function : Author
Wei Wang
  • Function : Author
Thorsten Warneke
  • Function : Author
Paul O. Wennberg
  • Function : Author
Helen M. Worden
  • Function : Author
Debra Wunch
  • Function : Author

Abstract

Observations of carbon monoxide (CO) from the Measurements Of Pollution In The Troposphere (MOPITT) instrument aboard the Terra spacecraft were expected to have an accuracy of 10 % prior to the launch in 1999. Here we evaluate MOPITT Version 7 joint (V7J) thermal-infrared and near-infrared (TIR-NIR) retrieval accuracy and precision and suggest ways to further improve the accuracy of the observations. We take five steps involving filtering or bias corrections to reduce scatter and bias in the data relative to other MOPITT soundings and ground-based measurements. (1) We apply a preliminary filtering scheme in which measurements over snow and ice are removed. (2) We find a systematic pairwise bias among the four MOPITT along-track detectors (pixels) on the order of 3-4 ppb with a small temporal trend, which we remove on a global scale using a temporally trended bias correction. (3) Using a small-region approximation (SRA), a new filtering scheme is developed and applied based on additional quality indicators such as the signal-to-noise ratio (SNR). After applying these new filters, the root-mean-squared error computed using the local median from the SRA over 16 years of global observations decreases from 3.84 to 2.55 ppb. (4) We also use the SRA to find variability in MOPITT retrieval anomalies that relates to retrieval parameters. We apply a bias correction to one parameter from this analysis. (5) After applying the previous bias corrections and filtering, we compare the MOPITT results with the GGG2014 ground-based Total Carbon Column Observing Network (TCCON) observations to obtain an overall global bias correction. These comparisons show that MOPITT V7J is biased high by about 6 %-8 %, which is similar to past studies using independent validation datasets on V6J. When using TCCON spectrometric column retrievals without the standard airmass correction or scaling to aircraft (WMO scale), the ground- and satellite-based observations overall agree to better than 0.5 %. GEOS-Chem data assimilations are used to estimate the influence of filtering and scaling to TCCON on global CO and tend to pull concentrations away from the prior fluxes and closer to the truth. We conclude with suggestions for further improving the MOPITT data products.
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insu-03718070 , version 1 (09-07-2022)

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Jacob K. Hedelius, Tai-Long He, Dylan B. A. Jones, Bianca C. Baier, Rebecca R. Buchholz, et al.. Evaluation of MOPITT Version 7 joint TIR-NIR XCO retrievals with TCCON. Atmospheric Measurement Techniques, 2019, 12, pp.5547-5572. ⟨10.5194/amt-12-5547-2019⟩. ⟨insu-03718070⟩
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