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Keywords:

  • secondary eyewall;
  • vortex Rossby waves

[1] The Weather Research and Forecast model is used to simulate the secondary eyewall genesis (SEG) and evolution in Hurricane Wilma (2005). The structure and time evolution of the secondary eyewall are well captured. The theory of empirical normal modes is then applied to study the SEG. For azimuthal wavenumber 1 anomalies, the wave activity spectra indicate that the leading modes (1 and 2), are vortex Rossby waves (VRWs). The Eliassen-Palm (EP) theorem is used to diagnose the impact of the propagating waves on the formation of the secondary eyewall. Analysis of the EP flux and its time-mean divergence show that in the lower troposphere the VRWs propagate outward outside the primary eyewall. The fact that the critical radius of the leading modes is located close to the region where the secondary eyewall eventually develops suggests that VRWs play an important role in SEG.