西太平洋暖池热盐结构温度场的时空变化

摘要

Based on the monthly temperature and salinity data during 1950-2011,the averaged temperature 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 ℃C isotherm as the boundary of the WPWP.The spatial and temporal variability of temperature anomaly fields in the ML,BL and DL is analyzed using an empirical orthogonal function (EOF) analysis method,respectively.In addition,the influences of the zonal wind stress,zonal currents and sea surface heat fluxes in the WPWP on the first two modes of these anomaly fields are also examined,respectively.The analysis results show that the first mode suggests that the temperature fields at three layers in the WPWP all have strong interannual variability and long-term trend and undertake a regime shift before and after 1985,while the second mode indicates that the temperature fields at three layers in the westernWPWP all have strong interannual variability and long-term trend and undertake a regime shift before and after 1995.The further analysis also indicates that the interannual variability in the first two modes of ML (including BL) temperature anomaly field is primarily controlled by zonal winds and South Equatorial Current (SEC),while the interannual variability in the first two modes of DL temperature anomaly field is mainly affected by SEC and Equatorial Undercurrent.%基于1950-2011年间热带太平洋月平均温盐度资料,以28℃等温线作为暖池的定义标准,分别计算了暖池区(20°N-15°S,120°E-140°W)各网格点混合层、障碍层和深层的平均温度,从而构成了暖池热盐结构的温度场.据此,运用EOF分析法研究了暖池混合层、障碍层和深层温度距平场的时空变化特征,并探讨了纬向风、纬向流和海面净热通量等要素对这3层温度场主要模态的影响.结果表明,第一模态揭示了暖池中东部3层温度都具有显著的年际变化和长期变化趋势,并在1985年前后经历了一次气候跃变,而第二模态则基本反映了暖池西部3层温度皆存在着明显的年际变化和长期变化趋势,并在1995年前后经历了一次气候跃变.暖池混合层(包括障碍层)温度场前两个模态的年际振荡主要是由纬向风和南赤道流(SEC)共同引起的,而暖池深层温度场前两个模态的年际振荡则是由SEC和赤道潜流(EUC)共同调制的.