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Regional Features of the 20-30 Day Periodic Behavior in the Southern Hemisphere Summer Circulation
  • Zhaoyu Liu,
  • Lei Wang
Zhaoyu Liu
Purdue University
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Lei Wang
Purdue University

Corresponding Author:leiwang@purdue.edu

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The Southern Hemispheric (SH) storm tracks exhibit a robust intraseasonal periodicity of 20-30 days as the leading mode of zonal-mean eddy kinetic energy. To what extent this hemispheric-scale mode of variability translates to smaller scales remains debated. This work studies the regional features of SH storm tracks through the filtered variance of local finite-amplitude wave activity. While the synoptic variance is zonally elongated over the storm track, we find a strong enhancement of intraseasonal variability within the South Pacific with a minimum strength of the storm track. This enhanced region is marked with 20-30 day periodic behavior of local wave activity and precipitation and is driven by enhanced variability of low-level eddy heat flux on the same timescale. The local nature of 20-30 day periodicity offers a potential source of intraseasonal predictability for weather analysts and forecasters.
26 Apr 2023Submitted to ESS Open Archive
02 May 2023Published in ESS Open Archive