Comprehensive evaluation of the Copernicus Atmosphere Monitoring Service (CAMS) reanalysis against independent observations

Abstract

The Copernicus Atmosphere Monitoring Service (CAMS) is operationally providing forecast and reanalysis products of air quality and atmospheric composition. In this article, we present an extended evaluation of the CAMS global reanalysis data set of four reactive gases, namely, ozone (O3), carbon monoxide (CO), nitrogen dioxide (NO2), and formaldehyde (HCHO), using multiple independent observations. Our results show that the CAMS model system mostly provides a stable and accurate representation of the global distribution of reactive gases over time. Our findings highlight the crucial impact of satellite data assimilation and emissions, investigated through comparison with a model run without assimilated data. Stratospheric and tropospheric O3 are mostly well constrained by the data assimilation, except over Antarctica after 2012/2013 due to changes in the assimilated data. Challenges remain for O3 in the Tropics and high-latitude regions during winter and spring. At the surface and for short-lived species (NO2), data assimilation is less effective. Total column CO in the CAMS reanalysis is well constrained by the assimilated satellite data. The control run, however, shows large overestimations of total column CO in the Southern Hemisphere and larger year-to-year variability in all regions. Concerning the long-term stability of the CAMS model, we note drifts in the time series of biases for surface O3 and CO in the Northern midlatitudes and Tropics and for NO2 over East Asia, which point to biased emissions. Compared to the previous Monitoring Atmospheric Composition and Climate reanalysis, changes in the CAMS chemistry module and assimilation system helped to reduce biases and enhance the long-term temporal consistency of model results for the CAMS reanalysis.

Comment on gmd-2021-318

“…For CO there is typically an underestimation in the simulated surface concentration (Huijnen et al, 2019), albeit for regions far away from high emission sources, while this is efficiently corrected by the data assimilation in CAMSRA. For the surface over the North Hemispheric midlatitude continents, CAMSRA typically shows seasonal biases in the monthly mean O3, with a negative bias during wintertime and a positive bias during summertime (Wagner et al, 2021). A similar performance is noticed for its 85 control simulation which excludes data assimilation of trace gases.…”

“…Inness 70 et al (2020). Another application of this system has been the production of a consistent, long-term reanalysis dataset from 2003 to present (Inness et al, 2019;Wagner et al, 2021), which can be used to analyze interannual variability in atmospheric composition (Huijnen et al, 2020). Also, as the reanalysis is using a fixed model configuration (IFS cycle 42R1), this dataset can be as well used as a reference for assessing changes in the performance of the IFS and updates to the operational chemistry modules since that cycle.…”

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

“…To this end, satellite retrievals of total column CO, tropospheric column NO 2 , aerosol optical depth, and total column, partial column and profile ozone retrievals are assimilated in the IFS system. More details on the satellite retrievals (product, satellite, period) assimilated in CAMSRA can be found in Table 1 of the CAMSRA evaluation study by Wagner et al (2021). In addition, meteorological observations, including satellite, PILOT, in situ, radiosonde, dropsonde, and aircraft measurements are also incorporated in IFS.…”

FORCAsT‐gs: Importance of Stomatal Conductance Parameterization to Estimated Ozone Deposition Velocity

“…Ozone concentration data were obtained for IT-Cp2, FI-Hyy, and US-Blo but are not readily available for US-Ha1 or BR-Sa1 for the periods considered in this study (Table S1). For these sites we used reanalysis data from the Copernicus Atmospheric Monitoring Service (CAMS; https://atmosphere.copernicus.eu) which have been shown to reproduce observed tropospheric ozone to within 10% (see e.g., Inness et al, 2013;Wagner et al, 2021).…”