Interannual and interdecadal rainfall variations in the Hawaiian Islands
Interannual and interdecadal rainfall variations in the Hawaiian Islands
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DOI：
10.1175/jcli3578.1
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发表时间：
2005-11-01
影响因子：
4.9
通讯作者：
Chen, HQ
中科院分区：
文献类型：
--
作者：
Chu, PS;Chen, HQ
夏威夷的降雨量表现出年际和年代际变化。在年际时间尺度上，夏威夷在大多数厄尔尼诺事件期间趋于干燥，但在没有厄尔尼诺的情况下也会出现低降雨。在年代际时间尺度上，夏威夷降水与太平洋年代际振荡（PDO）信号显著负相关;从20世纪70年代中期到2001年，降雨量一直很低，在此之前是一个持续近28年的高降雨期。冬季差异模式[11月-12月-1月-2月-3月（NDJFM）]降雨的复合材料的极端干燥和潮湿的冬天在干燥和潮湿的时代，分别进行了研究。这些模式（即，然后将DRY减去WET）与厄尔尼诺和PDO的建设性匹配条件的差异（即，厄尔尼诺/+PDO减去拉尼娜/-PDO）。相对于El Nino/PDO阶段，干旱的幅度在基于厄尔尼诺的阶段增强。研究了相应的大尺度大气环流合成。在这两个阶段之间显示出类似的模式。然而，非常强大和更深的下沉运动在夏威夷揭示在高度-纬度部分的Elnino/PDO阶段的分析相比。此外，一个异常的纬向环流圈是建立在副热带北太平洋上的一个明显的下降分支在夏威夷在马歇尔为基础的阶段。夏威夷以北的异常地面西风带、夏威夷上空的深下沉运动以及垂直积分的水汽通量辐散都不利于夏威夷的降水。
Hawaii rainfall has exhibited both interannual and interdecadal variations. On the interannual time scale, Hawaii tends to be dry during most El Nino events, but low rainfall also occurred in the absence of El Nino. On the interdecadal time scale, Hawaii rainfall is negatively and significantly correlated with the Pacific decadal oscillation ( PDO) signal; an epoch of low rainfall persists from the mid-1970s to 2001, which is preceded by an epoch of high rainfall lasting for nearly 28 yr.Difference patterns in winter [November-December-January-February-March (NDJFM)] rainfall are investigated for composites of extremely dry and wet winters during the dry and wet epochs, respectively. These patterns (i.e., DRY minus WET) are then compared to the difference in constructive match conditions of El Nino and PDO (i.e., El Nino/+PDO minus La Nina/-PDO). Relative to the El Nino/PDO stage, the magnitude of dryness during the rainfall-based stage is enhanced. The corresponding large-scale atmospheric circulation composites are studied. Similar patterns are revealed between these two stages. However, anomalously stronger and deeper sinking motions over Hawaii are revealed in the height-latitude section of the rainfall-based analysis compared to the El Nino/PDO stage. Moreover, an anomalous zonal circulation cell is well established over the subtropical North Pacific with a pronounced descending branch over Hawaii in the rainfall-based stage. The band of anomalous surface westerlies to the north of Hawaii, and the deep sinking motion as well as the anomalously vertically integrated moisture flux divergence over Hawaii are all unfavorable for rainfall in Hawaii.