西太平洋暖池时空分布特征及其与ENSO的关系

应用NCEP/NCAR SST资料和SODA海温资料,分析研究了热带太平洋海温场的变化特征,讨论了气候突变前后热带西太平洋暖池(以下简称WPWP)形态的显著变化及其差异,由此重新界定了WPWP的范围,并进一步分析了WPWP的时空变化特征。结果表明,新界定的WPWP气候平均场与前人定义的气候平均场分布特征基本相同,但也存在一定的差异。新界定的WPWP的优点在于它不仅能够客观反映出气候(海洋)突变前后西太平洋暖池的时空变化特征,而且重要的是可以避免由前人定义的WPWP与东太平洋暖池合为一体的现象发生,从而避免人为地计算WPWP面积变化带来的结果差异。新界定的WPWP平均深度可达130 m左右,呈现出西浅东深的"耳状"分布特征,在冬春季节,南北(经向)窄东西(纬向)宽,呈纬向带状分布;在夏秋季节,WP-WP明显向北扩展。平均深度最大中心位于(5°S,180°)附近。由WPWP区域不同深度的异常海温变化与Niño3指数的相关分析可知,WPWP次表层异常海温变化与Niño3指数呈显著的负相关关系,而与表层的异常海温的关系并不密切,这一结果进一步证明了西太平洋暖池对ENSO的贡献是来自次表层异常海温的东传。

Spatial and temporal distribution of the western Pacific warm pool and the relationship with ENSO cycle

Based on the NCEP/NCAR sea surface temperature (SST) data and the SODA sea temperature data in different depths, the variability of the sea temperature field is studied in the tropical Pacific Ocean.The difference of tropical western Pacific warm pool (WPWP) in shape structure between before and after climate shift has been discussed and then the WPWP has been defined over again.The spatial and temporal variability of the WPWP which is defined anew has been analyzed.The results indicate that the climatological depth of the WPWP by new definition is about 130m and with an "ear" shape structure that is shallow in the west and deep in the east.The WPWP is narrow in the north-south direction and broad in the eastwest direction during winter and spring.The WPWP expands northward during summer and autumn.The climatological deepest center of the WPWP is at about (5°S, 180°) and it is the shallowest during the summer and the deepest during the winter and spring.The variability of the WPWP depth correlated negatively with the index of Niño3.Moreover, the analysis of correlation between sea temperature anomaly at different depths in the WPWP and the index of Niño3 indicates that the east ward propagation of sea temperature anomaly at subsurface layer in the WPWP has major effect on the occurring of ENSO events, but the variability of sea surface temperature anomaly has no close relationship with the ENSO events.