Role of ENSO in the interannual relationship between Tibetan Plateau winter snow cover and Northwest Pacific tropical cyclone genesis frequency

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• 作者：RuiFen Zhan ; YiHui Ding ; LiGuang Wu ; XiaoTu Lei
• 关键词：Western North Pacific ; Tropical cyclone ; Snow cover over the Tibetan Plateau ; ENSO ; Interdecadal shift
• 刊名：Science China Earth Sciences
• 出版年：2016
• 出版时间：October 2016
• 年：2016
• 卷：59
• 期：10
• 页码：2009-2021
• 全文大小：1,359 KB
• 刊物主题：Earth Sciences, general;
• 出版者：Springer Berlin Heidelberg
• ISSN：1869-1897
• 卷排序：59

文摘

Previous studies have revealed a significantly negative correlation between prior winter snow cover over the Tibetan Plateau (TPSC) and tropical cyclone genesis frequency (TCF) over the western North Pacific (WNP) in the following typhoon season. This study revisited this relationship based on long-term observational data. The results showed that the interannual correlation between TCF over the WNP and TPSC experienced a shift in the early 1990s. This correlation is significant during only 1993–2012 and is considerably weak during 1976–1992. The possible reasons causing the shift were examined further, and the results demonstrated that the central Pacific (CP) El Niño-Southern Oscillation (ENSO) has played a vital role in intensifying the interannual relationship between TCF over the WNP and TPSC since the early 1990s. During 1993–2012, TPSC was negatively related to CP ENSO. When TPSC was higher than (lower than) normal, CP ENSO was often in its cold (warm) phase. Such a combination remarkably enhances the relationship of TPSC with the zonal land-sea thermal difference and thus with the summer monsoon over the WNP. Additionally, it enhances the modulation of TPSC on the dynamical environments controlling TCF. As a result, the linkage between TPSC and TCF was significantly strengthened in this period. In sharp contrast, due to the weak relationship between TPSC and ENSO followed by the weak modulation of TPSC on the summer monsoon over the WNP and the dynamical environment during 1976–1992, the linkage between TPSC and TCF was weak during this time period. The results from additional dynamical diagnostic analyses further showed that during 1993–2012 CP ENSO modulated the barotropic energy conversion of zonal winds over the WNP, contributing to the intensified relationship between TPSC and TCF. These results will improve seasonal forecasting of tropical cyclone activity over the WNP.