| 摘要: |
| 基于1950～2011年间的月平均温、盐度资料，以28℃等温线作为西太平洋暖池的定义标准，并取ΔT=-04℃，分别计算了暖池区（20°N～15°S，120°E～140°W）各格点混合层、障碍层和深层的平均盐度，构成了暖池热盐结构的盐度场.据此，运用EOF分解法分析了暖池热盐结构盐度距平场主要模态的变化特征及其与ENSO间的关系，并探讨了主要模态的年际变异机理.结果表明，暖池热盐结构盐度场第一模态揭示了盐度场变异的关键区位于暖池中部；该模态具有2～4a的年际变化和准10a的年代际变化，并在1977年前后经历了一次气候跃变（此外，深层盐度场第一模态还在1999年前后发生了一次气候跃变），且在跃变前后与不同类型的ENSO事件有较密切的联系.暖池中部混合层和障碍层盐度的变化比较一致，即在跃变前盐度为偏高期，而在跃变后则变为偏低期.暖池中部深层盐度在1977年以前和1999年之后皆处于偏高期，而在1978～1999年间则处于偏低期.而且，从混合层至深层，盐度的变化幅度逐渐变小.进一步分析表明，暖池中部混合层和障碍层盐度的年际变化主要是由纬向风、南赤道流（SEC）和降水共同引起的，即当东风增强（减弱）时，强（弱）SEC将携带更多（少）的高盐水进入混合层或潜沉至障碍层，同时局地降水的减少（增多），也使得混合层和障碍层的盐度增加（减少）；深层盐度的年际变化主要是由SEC和赤道潜流（EUC）导致的，即当SEC增强（减弱）时，将有更多（少）的高盐水进入暖池，而当EUC增强（减弱）时则有更多（少）的低盐水流出暖池，从而使得暖池的深层盐度升高（降低） |
| 关键词: 物理海洋学 西太平洋暖池 热盐结构 时空变化 ENSO |
| DOI：10.3969/J.ISSN.2095-4972.2016.03.001 |
|
| 基金项目:国家重点基础研究发展计划资助项目(2012CB417402)；中科院先导专项A资助项目（XDA11020104）；国家自然科学基金资助项目（41476019）；全球变化与海气相互作用资助项目（GASI 03 01 01 02） |
|
| Leading EOF mode of salinity anomaly fields of the Western Pacific Warm Pool thermohaline structure |
| QIN Sisi,ZHANG Qilong,YIN Baoshu |
| (Key Laboratory of Ocean Circulation and Waves， Institute of Oceanology，Chinese Academy of Sciences，Qingdao 266071， China; University of Chinese Academy of Sciences， Beijing 100049， China;Qingdao National Laboratory for Marine Science and TechnologyFunction Laboratory of Marine and Global Climate Change，Qingdao 266237,China; National Marine Environmental Forecasting Center,Beijing 100081,China) |
| Abstract: |
| Based on the monthly temperature and salinity data during 1950~2011， the averaged salinity fields in mixed layer （ML）， barrier layer （BL） and deep layer （DL） of the Western Pacific Warm Pool （WPWP） area （20°N~15°S，120°E~140°W） are calculated using 28℃ isotherm as the boundary of the WPWP. The spatial and temporal variability of salinity anomaly fields in the ML， BL and DL are analyzed with the empirical orthogonal function （EOF） analysis， respectively. In addition， the relationships between the leading EOF modes of these fields and El NioSouthern Oscillation （ENSO） are also discussed. Moreover， the influences of the zonal winds， zonal currents and precipitation in the WPWP on the first modes of these salinity anomaly fields are examined. As results， the first modes suggest that the central WPWP is a key area for salinity variability in these 3 layers， where the salinity has interannual variability with period of 2~4year and decadal variability and undertakes a regime shift before and after 1977 （DL salinity also does a shift before and after 1999）. Moreover， the modes are all well related to the different types of ENSO in different times. In the central WPWP， BL salinity varies relatively consistent with ML salinity. Namely， ML and BL are both in high salt period before 1977， and then they go into a low salt period. In contrast， while DL has 2 high salt periods before 1977 and after 1999， and only has a low salt period between 1977 and 1999. Furthermore， from ML to DL， the amplitude of salinity variation gradually becomes small. Further analysis also indicates that the interannual salinity variations in both ML and BL are primarily controlled together by zonal winds， South Equatorial Current （SEC） and precipitations， namely， when the easterly winds strengthen （weaken）， strong （weak） SEC would make more （less） high salinity water entering ML or diving into BL. When the precipitation decreases （increases） in the central WPWP， the salinity in both ML and BL increase （decrease）. In contrast， the interannual salinity variation in DL salinity is mainly affected by SEC and Equatorial Undercurrent （EUC）. i.e.， a strong （weak） SEC transports more （less） high salinity water entering the WPWP while a strong （weak） EUC carries more （less） low salinity water out of the WPWP， which will result in the increase （decrease） of salinity in DL． |
| Key words: Physical oceanography Western Pacific Warm Pool thermohaline structure spatial and temporal variability ENSO |
