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| Titel |
Environmental influences on the intensity changes of tropical cyclones over the western North Pacific |
| VerfasserIn |
Shoujuan Shu, Fuqing Zhang, Jie Ming, Yuan Wang |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 14, no. 12 ; Nr. 14, no. 12 (2014-06-25), S.6329-6342 |
| Datensatznummer |
250118836
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| Publikation (Nr.) |
 copernicus.org/acp-14-6329-2014.pdf |
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| Zusammenfassung |
| The influence of environmental conditions on the intensity changes of
tropical cyclones (TCs) over the western North Pacific (WNP) is investigated
through examination of 37 TCs during 2000–2011 that interacted directly with
the western North Pacific subtropical high (WNPSH). Comprehensive composite
analysis of the environmental conditions is performed for two stages of
storms: one is categorized as intensifying events (maximum wind speed
increases by 15 kn over 48 h) and the other is categorized as weakening
events (maximum wind speed decreases by 15 kn over 48 h). Comparison of the
composite analysis of these two cases show that environmental conditions
associated with the WNPSH play important roles in the intensity changes of
TCs over the WNP. When a TC moves along the southern periphery of the WNPSH,
the relatively weaker easterly environmental vertical wind shear helps bring
warm moist air from the south and southeast to its southeast quadrant within
500 km, which is favorable for the TC to intensify. However,
when a TC moves along the western edge of the WNPSH, under the combined
influences of the WNPSH and an upper-level westerly trough, a strong
westerly vertical shear promotes the intrusion of dry environmental air
associated with the WNPSH from the north and northwest, which may lead to
the inhibition of moisture supply and convection over the western half of the
TC and thus its weakening. These composite results are consistent with those
with additional geographic restrictions, suggesting that the dry air
intrusion and the vertical wind shear (VWS) associated with the WNPSH,
indeed affect the intensity changes of TCs over the WNP beyond the
difference related solely to variations in geographical locations. The
average sea surface temperature (SST) of 27.6 °C for the weakening
events is also lower than an average of 28.9 °C for the strengthening
events, but remains above the critical value of 27 °C for TC
intensification, suggesting that the SST may be regarded as a less positive
factor for the weakening events. |
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