A change in the relationship between tropical central Pacific SST variability and the extratropical atmosphere around 1990
A change in the relationship between tropical central Pacific SST variability and the extratropical atmosphere around 1990
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DOI：
10.1088/1748-9326/7/3/034025
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发表时间：
2012-09
影响因子：
6.7
通讯作者：
Jin‐Yi Yu;Mong-Ming Lu;Seon Tae Kim
中科院分区：
文献类型：
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作者：
Jin‐Yi Yu;Mong-Ming Lu;Seon Tae Kim
对1979-2009年热带中太平洋再分析资料的分析表明，1990年以前热带中太平洋海表温度（SST）变率与热带东太平洋SST变率的关系更为密切，1990年以后与北太平洋涛动（NPO）相关的海平面气压（SLP）变率的关系更为密切。只有在1990年以后，NPO才能激发热带中太平洋SST的大变化。与此相关的是，厄尔尼诺南方涛动（ENSO）海温异常在1990年以前以类似于东太平洋（EP）型ENSO的形式从热带太平洋东部向中部传播，而在1990年以后则与副热带北太平洋海温变率有着更密切的联系，以类似于中太平洋（CP）型ENSO的形式。研究表明，1990年以来NPO对热带太平洋影响的增强可能是导致CP型ENSO事件增多的原因。对这两个时期平均大气环流的分析表明，1990年后NPO影响的增强与Hadley环流的加强有关。
A newly released reanalysis dataset covering the period 1979–2009 is analyzed to show that the sea surface temperature (SST) variability in the tropical central Pacific is more closely related to the SST variability in the tropical eastern Pacific before 1990 but more closely related to sea level pressure (SLP) variations associated with the North Pacific Oscillation (NPO) after 1990. Only during the period after 1990 can the NPO excite large SST variability in the tropical central Pacific. Related to this change, El Niño Southern Oscillation (ENSO) SST anomalies tend to spread from the eastern to central tropical Pacific before 1990 in a pattern resembling that associated with the Eastern Pacific (EP) type of ENSO, but are more closely connected to SST variability in the subtropical north Pacific after 1990 with a pattern resembling that of the Central Pacific (CP) type of ENSO. This study concludes that the increased influence of the NPO on the tropical Pacific is a likely reason for the increasing occurrence of the CP type of ENSO since 1990. An analysis of the mean atmospheric circulation during these two periods suggests that the increased NPO influence is associated with a strengthening Hadley circulation after 1990.