Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 17, 2901-2920, 2017
https://doi.org/10.5194/acp-17-2901-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
24 Feb 2017
A decadal satellite record of gravity wave activity in the lower stratosphere to study polar stratospheric cloud formation
Lars Hoffmann1, Reinhold Spang2, Andrew Orr3, M. Joan Alexander4, Laura A. Holt4, and Olaf Stein1 1Jülich Supercomputing Centre, Forschungszentrum Jülich, Jülich, Germany
2Institut für Energie- und Klimaforschung, Forschungszentrum Jülich, Jülich, Germany
3British Antarctic Survey, NERC, Cambridge, UK
4NorthWest Research Associates, Inc., CoRA Office, Boulder, CO, USA
Abstract. Atmospheric gravity waves yield substantial small-scale temperature fluctuations that can trigger the formation of polar stratospheric clouds (PSCs). This paper introduces a new satellite record of gravity wave activity in the polar lower stratosphere to investigate this process. The record is comprised of observations of the Atmospheric Infrared Sounder (AIRS) aboard NASA's Aqua satellite from January 2003 to December 2012. Gravity wave activity is measured in terms of detrended and noise-corrected 15 µm brightness temperature variances, which are calculated from AIRS channels that are the most sensitive to temperature fluctuations at about 17–32 km of altitude. The analysis of temporal patterns in the data set revealed a strong seasonal cycle in wave activity with wintertime maxima at mid- and high latitudes. The analysis of spatial patterns indicated that orography as well as jet and storm sources are the main causes of the observed waves. Wave activity is closely correlated with 30 hPa zonal winds, which is attributed to the AIRS observational filter. We used the new data set to evaluate explicitly resolved temperature fluctuations due to gravity waves in the European Centre for Medium-Range Weather Forecasts (ECMWF) operational analysis. It was found that the analysis reproduces orographic and non-orographic wave patterns in the right places, but that wave amplitudes are typically underestimated by a factor of 2–3. Furthermore, in a first survey of joint AIRS and Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) satellite observations, nearly 50 gravity-wave-induced PSC formation events were identified. The survey shows that the new AIRS data set can help to better identify such events and more generally highlights the importance of the process for polar ozone chemistry.

Citation: Hoffmann, L., Spang, R., Orr, A., Alexander, M. J., Holt, L. A., and Stein, O.: A decadal satellite record of gravity wave activity in the lower stratosphere to study polar stratospheric cloud formation, Atmos. Chem. Phys., 17, 2901-2920, https://doi.org/10.5194/acp-17-2901-2017, 2017.
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Short summary
We introduce a 10-year record (2003–2012) of AIRS/Aqua observations of gravity waves in the polar lower stratosphere. The data set was optimized to study the impact of gravity waves on the formation of polar stratospheric clouds (PSCs). We discuss the temporal and spatial patterns of gravity wave activity, validate explicitly resolved small-scale temperature fluctuations in the ECMWF data, and present a survey of gravity-wave-induced PSC formation events using joint AIRS and MIPAS observations.
We introduce a 10-year record (2003–2012) of AIRS/Aqua observations of gravity waves in the...
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