Quantification of the contribution of equatorial Kelvin waves to the QBO wind reversal in the stratosphere

Ern, M.; Preusse, P.

doi:10.1029/2009GL040493

Journal Article

PreJuSER-6488

Quantification of the contribution of equatorial Kelvin waves to the QBO wind reversal in the stratosphere

Ern, M.FZJ* ; Preusse, P.FZJ*

2009
American Geophysical Union Washington, DC

Geophysical research letters 36, L21801 (2009) [10.1029/2009GL040493]

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Please use a persistent id in citations: http://hdl.handle.net/2128/20847 doi:10.1029/2009GL040493

Abstract: Both global scale waves (e. g., Kelvin, equatorial Rossby, or Rossby-gravity waves) and mesoscale gravity waves contribute to the wind reversals of the quasi biennial oscillation (QBO). The relative contributions of the different wave types are highly uncertain. In our work we quantify the contribution of equatorial Kelvin waves to the reversal from stratospheric easterlies to westerlies averaged over two QBO cycles in the period 2002-2006. Our analysis is based on longitude-time spectra of temperatures measured by the SABER satellite instrument, as well as temperatures from ECMWF operational analyses. Kelvin waves of zonal wavenumber 1-6 and periods longer than 2.5 days are covered. It is found that the contribution of Kelvin waves is about 30-50% of the observed wind reversal and only 20-35% of the expected total wave forcing. The larger part of the wave forcing therefore has to be contributed by other waves, likely mesoscale gravity waves. Citation: Ern, M., and P. Preusse (2009), Quantification of the contribution of equatorial Kelvin waves to the QBO wind reversal in the stratosphere, Geophys. Res. Lett., 36, L21801, doi: 10.1029/2009GL040493.

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Geosciences, Multidisciplinary

Note: The work of M. Ern was supported by the European Commission (European Union's 6th framework program) within the EC Integrated Project SCOUT-O3 (505390-GOCE-CT-2004). We thank the whole SABER team, in particular M. G. Mlynczak, J. M. Russell III, and L. L. Gordley, for providing the excellent data set of SABER temperatures. Thanks also go to the European Centre for Medium-Range Weather Forecasts (ECMWF) for providing the ECMWF operational analyses used. Helpful comments by two anonymous reviewers are gratefully acknowledged.

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