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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 28, issue 2
Ann. Geophys., 28, 531–547, 2010
https://doi.org/10.5194/angeo-28-531-2010
© Author(s) 2010. This work is distributed under
the Creative Commons Attribution 3.0 License.
Ann. Geophys., 28, 531–547, 2010
https://doi.org/10.5194/angeo-28-531-2010
© Author(s) 2010. This work is distributed under
the Creative Commons Attribution 3.0 License.

  15 Feb 2010

15 Feb 2010

Analysis of gravity-waves produced by intense tropical cyclones

F. Chane Ming1, Z. Chen2, and F. Roux3 F. Chane Ming et al.
  • 1Laboratoire de l'Atmosphère et des Cyclones, UMR 8105, CNRS-Météo-France, Université de la Réunion, La Réunion, France
  • 2Institute of Atmospheric Physics – Chinese Academy of Sciences, Beijing, China
  • 3Laboratoire d'Aérologie, UMR CNRS – Université Paul Sabatier, Toulouse, France

Abstract. Conventional and wavelet methods are combined to characterize gravity-waves (GWs) produced by two intense tropical cyclones (TCs) in the upper troposphere and lower stratosphere (UT/LS) from GPS winsonde data. Analyses reveal large contribution of GWs induced by TCs to wave energy densities in the UT/LS. An increase in total energy density of about 30% of the climatological energy density in austral summer was estimated in the LS above Tromelin during TC Dina. Four distinct periods in GW activity in relation with TC Faxai stages is observed in the UT. Globally, GWs have periods of 6 h–2.5 days, vertical wavelenghts of 1–3 km and horizontal wavelengths <1000 km in the UT during the evolution of TCs. Horizontal wavelengths are longer in the LS and about 2200 km during TCs. Convective activity over the basin and GW energy density were modulated by mixed equatorial waves of 3–4 days, 6–8 days and 10–13 days confirmed by Hövmöller diagram, Fourier and wavelet analyses of OLR data. Moreover, location of GW sources is below the tropopause height when TCs are intense otherwise varies at lower tropospheric heights depending on the strength of convection. Finally, the maximum surface wind speeds of TCs Dina and Faxai can be linearly estimated with total energy densities.

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