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Titel |
Relationship between the intraseasonal IPCO and tropical cyclogenesis over the Indo-western North Pacific during summertime |
VerfasserIn |
Qiuyun Wang, Jianping Li, Yanjie Li, Jingwen Zhang |
Konferenz |
EGU General Assembly 2017
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Medientyp |
Artikel
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Sprache |
en
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Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 19 (2017) |
Datensatznummer |
250142646
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Publikation (Nr.) |
EGU/EGU2017-6290.pdf |
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Zusammenfassung |
The influence of the intraseasonal Indo-western Pacific convection oscillation (IPCO) on the
tropical cyclone (TC) genesis location and frequency over the Indo-western North Pacific
during the summertime (MaytOctober) is explored in this paper. Observational analysis
shows that the impacts of the intraseasonal IPCO on TCs over the Indo-western North Pacific
features in evident “locational phase lock of TC genesis” and distinct differences in TC
frequency. In term of the WNP, when the intraseasonal IPCO is positive phase, there tends
to be much more TCs, especially in the South China Sea (SCS), and more TCs
generate in the west of the WNP and lower latitude (around 5º-20ºN); vice versa. At
the positive intraseasonal IPCO phase, the atmosphere gains heat through both
sea-air interaction and the latent heat release of cumulus convective condensation,
and the anomalous cyclonic circulation weakens the western Pacific subtropical
high (WPSH), these conditions do favor the TC genesis. Moreover, the shrinking
WPSH, the enhanced heat transfer from sea to air at the lower latitude as well as
the westward shifts of heating center and anomalous cyclonic circulation lock TC
genesis locations in the west of the WNP and lower latitude. The opposite situation
occurs at negative phase. As for the North Indian Ocean (NIO), the TC genesis
locations at the positive intraseasonal IPCO phase mainly situate in 13º-20ºN and
distribute closer to Indian Peninsula, particularly in the Arabian Sea (ARB), in
contrast, the spatial distribution is more dispersed at the negative intraseasonal
IPCO phase. However, the total TC frequencies at two intraseasonal IPCO phases
are similar. These features come largely from the differences in the area featuring
conditions between the northern and southern regions of 13ºN in the NIO: at the
positive intraseasonal IPCO phase, to the northern region of 13ºN, the environmental
conditions are similar to the case of the WNP except without the WPSH control, and the
reversed situations are observed over the southern region of 13ºN, which lead to
northward shift of TC genesis location. The negative phase reflects an opposite situation. |
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