太平洋—日本遥相关型的年代际变化特征及其成因

Interdecadal Variation in Pacific-Japan Teleconnection Patterns and Possible Causes

本文首先利用NCEP/NCAR和ERA-40再分析资料以及中国753站降水资料对太平洋—日本(Pacific-Japan,简称P-J)遥相关型在上世纪70年代末期气候突变前后的年代际变化特征进行了分析研究。结果表明,在气候突变前后,P-J遥相关型的位置发生了显著的变化,气候突变以后其位置明显向西向南偏移。这种位置的变化同样也反映在纬向风场、高度场上。研究结果还表明,气候突变前后P-J遥相关型的年代际变化与热带太平洋和印度洋海温变化有关。气候突变之前,P-J遥相关型的变化与前期热带太平洋和印度洋海温不存在显著的相关;但在气候突变之后,P-J遥相关型与前期冬春季的热带太平洋、印度洋海温之间存在大范围的显著相关区。这种P-J遥相关型与热带太平洋、印度洋海温相关关系的年代改变可能与1970年代中期以后赤道中东太平洋海温变化振幅明显增强有关。随后,本文采用一个高分辨率的大气环流模式,通过一系列的数值试验也进一步证实了1970年代末期热带太平洋和印度洋海温的年代际变化确实可致使P-J遥相关型位置发生相应的改变。

Based on NCEP/NCAR, the ERA-40 reanalysis dataset, and the precipitation dataset from 753 stations in China, the interdecadal variation of the summer Pacific-Japan （P-J） teleconnection pattem is investigated. Results indicate that the summer P-J teleconnection pattern experienced a marked interdacadal variation around the late 1970s, with its major teleconnection centers shifting southwestward. This interdecadal variation is clearly reflected in the fields of 850 hPa zonal wind and 500 hPa geopotential heights. This study also shows that the P-J teleconnection pattern in interdecadal variation is closely related to interdecadal variations in sea surface temperature （SST） over the tropical Pacific and Indian Oceans. Prior to the late 1970s, no high correlation coefficients are found between the summer P-J teleconnection pattem and its previous winter SST. However, after that, the P-J teleconnection pattern is found to be highly correlated to the SST over the tropical Pacific and Indian Oceans, both in the previous winter and spring. This interdecadal change in the relationship between the P-J teleconnection pattern and the SSTs over the tropical Pacific and Indian Ocean is probably due to the fact that the SST interannual variability over the tropical central and eastern Pacific has increased remarkably since the late 1970s. A high-resolution atmospheric general circulation model （GCM） is used to examine the effect of SSTs over the tropical Pacific and Indian Oceans on the interdecadal variation in the P-J teleconnection pattern through a model control experiment and several sensitivity experiments. GCM results further confirm that the interdecadal variation in SSTs over the tropical Pacific and Indian Oceans can indeed lead to the interdecadal variability of the P-J teleconnection pattern.