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| Titel |
Regime-dependent nonstationary relationship between the East Asian winter monsoon and North Pacific Oscillation |
| VerfasserIn |
Gyundo Pak, Young-Hyang Park, Frédéric Vivier, Young-Oh Kwon, Kyung-Il Chang |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250094294
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| Publikation (Nr.) |
 EGU/EGU2014-9698.pdf |
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| Zusammenfassung |
| The East Asian winter monsoon (EAWM) and the North Pacific Oscillation (NPO) constitute two outstanding surface atmospheric circulation patterns affecting the winter sea surface temperature (SST) variability in the northwest Pacific Ocean. By analyzing data over a total of 48 winter seasons (1965-2012), our analyses show that the indices of the above atmospheric circulation patterns underwent an abrupt regime shift around 1988, from a strong winter monsoon regime before 1988 to a weaker monsoon regime afterward. The 11-year running correlation indicates that the EAWM and NPO were tightly connected to each other during the last two thirds of the strong monsoon regime (1973-1987; SM-HC epoch) but nearly completely disconnected during the first two thirds of the weak monsoon regime (1988-2002; WM-LC epoch). This regime-dependent nonstationary relationship between the EAWM and NPO is related to a tight (insignificant) statistical connection in sea level pressure variations between the Siberian high (SH) and NPO centers of action during the SM-HC (WM-LC) epoch. This is also associated with the pronounced decadal weakening of the SH system over the entire Eurasian continent after the 1988 regime shift as well as the concomitant, positive NPO/WP-like dipole change in surface and upper-level circulation patterns over the North Pacific. It is also shown that the EAWM and NPO are consistently well linked to the upper-level blocking events, Ural and Kamchatka blockings, which determine predominantly the variability of the SH and west Pacific teleconnection pattern (WP), respectively. The regime-dependent changes in atmospheric surface circulation affect differently the northwest Pacific SST. During the SM-HC epoch when the EAWM and NPO were strongly connected to each other, a very similar spatial pattern of SST anomalies was projected by these circulation modes, while a quite dissimilar and weakened pattern was observed during the WM-LC epoch when the EAWM and NPO were practically independent. In particular, the EAWM impact on SST during the latter epoch shrank remarkably into a limited area in the East China Sea, making a clear distinction from the NPO impact. |
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