Preprints
https://doi.org/10.5194/acp-2021-998
https://doi.org/10.5194/acp-2021-998

  22 Dec 2021

22 Dec 2021

Review status: this preprint is currently under review for the journal ACP.

A process-oriented evaluation of CAMS reanalysis ozone during tropopause folds over Europe for the period 2003–2018

Dimitris Akritidis1, Andrea Pozzer2, Johannes Flemming3, Antje Inness3, Philippe Nédélec4, and Prodromos Zanis1 Dimitris Akritidis et al.
  • 1Department of Meteorology and Climatology, School of Geology, Aristotle University of Thessaloniki, Thessaloniki, Greece
  • 2Atmospheric Chemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
  • 3European Centre for Medium-Range Weather Forecasts (ECMWF), Reading, UK
  • 4LAERO, Université de Toulouse, UT3, CNRS, IRD, Toulouse, France

Abstract. Tropopause folds are the key process underlying stratosphere-to-troposphere transport (STT) of ozone, thus, affecting tropospheric ozone levels and variability. In the present study we perform a process-oriented evaluation of Copernicus Atmosphere Monitoring Service (CAMS) reanalysis (CAMSRA) O3 during folding events, over Europe and for the time period from 2003 to 2018. A 3-D labeling algorithm is applied to detect tropopause folds in CAMSRA, while ozonesonde data from WOUDC (World Ozone and Ultraviolet Radiation Data Centre) and aircraft measurements from IAGOS (In-service Aircraft for a Global Observing System) are used for CAMSRA O3 evaluation. The profiles of observed and CAMSRA O3 concentrations indicate that CAMSRA reproduces the observed O3 increases in the troposphere during the examined folding events. Nevertheless, at some of the examined sites, CAMSRA overestimates the observed O3 concentrations, mostly at the upper portion of the observed increases, with a median fractional gross error (FGE) among the examined sites > 0.2 above 400 hPa. The use of a control run without data assimilation, reveals that the aforementioned overestimation of CAMSRA O3 arises from the data assimilation implementation. Overall, although data assimilation assists CAMSRA O3 to follow the observed O3 enhancements in the troposphere during the STT events, it introduces biases in the upper troposphere resulting in no clear quantitative improvement compared to the control run without data assimilation. Less biased assimilated O3 products, with finer vertical resolution in the troposphere, in addition to higher IFS (Integrated Forecasting System) vertical resolution, are expected to provide a better representation of O3 variability during tropopause folds.

Dimitris Akritidis et al.

Status: open (until 02 Feb 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2021-998', Anonymous Referee #1, 11 Jan 2022 reply
  • RC2: 'Comment on acp-2021-998', Anonymous Referee #2, 17 Jan 2022 reply

Dimitris Akritidis et al.

Dimitris Akritidis et al.

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Short summary
We perform a process-oriented evaluation of Copernicus Atmosphere Monitoring Service (CAMS) reanalysis (CAMSRA) O3 over Europe, using WOUDC (World Ozone and Ultraviolet Radiation Data Centre) ozonesondes and IAGOS (In-service Aircraft for a Global Observing System) aircraft measurements. Chemical data assimilation assists CAMSRA to reproduce the observed O3 increases in the troposphere during the examined folding events, yet it mostly results in O3 overestimation in the upper troposphere.
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