Modulation of the Tibetan Plateau Snow Cover on the ENSO Teleconnections: From the East Asian Summer Monsoon Perspective
Modulation of the Tibetan Plateau Snow Cover on the ENSO Teleconnections: From the East Asian Summer Monsoon Perspective
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DOI：
10.1175/jcli-d-11-00135.1
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发表时间：
2012-03
影响因子：
4.9
通讯作者：
Zhiwei Wu;Jianping Li;Zhihong Jiang;Tingting Ma
中科院分区：
文献类型：
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作者：
Zhiwei Wu;Jianping Li;Zhihong Jiang;Tingting Ma
东亚夏季风（EASM）在具有相同ENSO期的年份之间可能表现出相当大的变异性。这种不一致性降低了基于ENSO的EASM可预测性。对三维环流结构的研究表明，典型的ENSO信号在TPSC减少的夏季比在TPSC过多的夏季更强。数值和理论证据表明，TPSC的异常减少会迫使对流层上层的正位势高度异常，并减弱西南太平洋和西北太平洋的急流。在这种基本状态纬向流的控制下，温带罗斯比波对ENSO强迫的响应通常具有较大的振幅和明显的西向发展。在这种情况下，ENSO将其影响扩大到东亚，并加强了与东亚地区的联系。
TheEastAsiansummermonsoon(EASM)mayexhibitratherlargevariabilitybetweenyearscharacterized by the same ENSO phase. Such inconsistency reduces the EASM predictability based on ENSO. Results in this study show that the Tibetan Plateau snow cover (TPSC) exerts a modulating effect on ENSO teleconnections and ENSO significantly correlates with the EASM only during the reduced TPSC summers. Three-dimensional circulation structures are examined to manifest that the typical ENSO signals in reduced TPSC summers tend to be stronger than in excessive TPSC summers. Numerical and theoretical evidences indicate that the anomalously reduced TPSC can force positive geopotential height anomalies at the upper troposphereandweakenthejetstreamsacrosseasternAsiaandnorthwesternPacific.Governedbysuchbasic state zonal flows, the extratropical Rossby wave response to the ENSO forcing usually has a larger amplitude and pronounced westward development. In such case, ENSO extends its influences to eastern Asia and enhances its connection with the EASM.