Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
doi:10.5194/acp-2017-71
© Author(s) 2017. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
17 Feb 2017
Review status
This discussion paper is under review for the journal Atmospheric Chemistry and Physics (ACP).
Validation of meteorological analyses and trajectories in the Antarctic lower stratosphere using Concordiasi superpressure balloon observations
Lars Hoffmann1, Albert Hertzog2, Thomas Rößler1, Olaf Stein1, and Xue Wu1,3 1Jülich Supercomputing Centre, Forschungszentrum Jülich, Jülich, Germany
2Laboratoire de Météorologie Dynamique, École Polytechnique, IPSL, Palaiseau, France
3Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
Abstract. In this study we validated temperatures and horizontal winds of meteorological analyses in the Antarctic lower stratosphere, a region of the atmosphere that is of major interest regarding chemistry and dynamics of the polar vortex. The validation was performed with long-duration observations from 19 superpressure balloon flights during the Concordiasi field campaign in September 2010 to January 2011. Our intercomparison covers the European Centre for Medium-Range Weather Forecasts (ECMWF) operational analysis, the ERA-Interim reanalysis, the Modern-Era Retrospective analysis for Research and Applications (MERRA), and the National Centers for Environmental Prediction and National Center for Atmospheric Research (NCEP/NCAR) reanalysis. We found that large-scale temperatures of the analyses have a mean precision of 0.4–1.4 K and a warm bias of 0.4–2.1 K at about 17–18.5 km altitude and 60–85° S. Zonal and meridional winds have a mean precision of 0.9–2.3 m/s and a bias below ±0.5 m/s in the same region. Standard deviations related to small-scale fluctuations such as gravity waves are reproduced at levels of 15–60 % for temperature and 30–60 % for the horizontal winds. We also used the balloon observations to validate trajectory calculations, where vertical motions of simulated trajectories were nudged to pressure measurements of the balloons to take into account changes in the overall mass configuration of the balloon-gondola system. We found relative horizontal transport deviations of 4.5–12 % and error growth rates of 60–170 km/day for 15-day trajectories. Dispersion simulations revealed some difficulties with the representation of subgrid-scale wind fluctuations in our Lagrangian transport model, as the spread of air parcels simulated with different analyses was not consistent. Although case studies suggest that the accuracy of trajectory calculations is influenced by meteorological complexity, diffusion generally does not contribute significantly to transport deviations in our analysis. Overall, validation results are satisfactory and compare well to earlier studies using superpressure balloon observations. In most cases, best performance was achieved by the ECMWF operational analysis, having the best spatiotemporal resolution, followed by ERA-Interim, MERRA, and finally NCEP/NCAR, having the lowest spatiotemporal resolution. Future work applying Eulerian or Lagrangian models to study the chemistry and dynamics of the polar vortex may use our validation results as additional guideline for error analyses.

Citation: Hoffmann, L., Hertzog, A., Rößler, T., Stein, O., and Wu, X.: Validation of meteorological analyses and trajectories in the Antarctic lower stratosphere using Concordiasi superpressure balloon observations, Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2017-71, in review, 2017.
Lars Hoffmann et al.
Lars Hoffmann et al.
Lars Hoffmann et al.

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Short summary
We validated temperatures, horizontal winds, and trajectory calculations of four meteorological analyses (ECMWF operational analysis, ERA-Interim, MERRA, and NCEP/NCAR) in the Antarctic lower stratosphere. The validation is based on 19 superpressure balloon flights during the Concordiasi campaign in September 2010 to January 2011. Future work applying Eulerian or Lagrangian models to study chemistry and dynamics of the polar vortex may use our results as guideline for error analyses.
We validated temperatures, horizontal winds, and trajectory calculations of four meteorological...
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