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- Title
Interannual variability of mid-high-latitude intraseasonal oscillation intensity at the southern hemisphere during austral summer.
- Authors
Yang, Shuangyan; Xu, Qinghan; Zhu, Zhiwei; Qi, Yanjun
- Abstract
The interannual variation of intraseasonal (10–30-day) oscillation (ISO) intensity for the eastward- and westward- propagating types over the mid-high latitudes in austral summer is studied. It indicates that during strong ISO years, the wave train has a larger amplitude and wider zonal influencing range. The wave train propagates eastward in both strong and weak eastward-propagating ISO years, while it propagates westward only in strong westward-propagating ISO years. One possible explanation for the larger magnitude of the wave train in strong ISO years is that the ISO perturbation acquires more energy from the mean flow through the barotropic kinetic energy and potential energy conversion. Based on the diagnostic results of the geopotential height trend, the maximum contributor to the eastward propagation is the same during strong and weak ISO years, as well as for the westward propagation. However, the relative contribution of the relative vorticity's meridional advection in weak years is smaller than that in strong years, which may be the reason why there is no significant westward propagation in weak ISO years. Due to the difference in amplitude and influencing range of the wave train during strong and weak ISO years, the two ISO types have different effects on the surface air temperate over land areas at the Southern Hemisphere. The interannual variation of the eastward-propagating ISO intensity appears to be linked to the El Niño-Southern Oscillation and Southern Annular Mode, while the westward-propagating ISO appears unrelated to them.
- Subjects
MADDEN-Julian oscillation; SOUTHERN oscillation; EL Nino; ANTARCTIC oscillation; KINETIC energy
- Publication
Climate Dynamics, 2024, Vol 62, Issue 5, p3859
- ISSN
0930-7575
- Publication type
Article
- DOI
10.1007/s00382-024-07103-7