Strengthening of tropical Indian Ocean teleconnection to the Northwest Pacific since the mid-1970s: An atmospheric GCM study
会议名称：《第七届全国优秀青年气象科技工作者学术研讨会》
会议日期：2010年
学科分类：07[理学] 070601[理学-气象学] 0706[理学-大气科学]
基 金：supported by the National Key Technology R&D Program 2008BAK50B02 the Natural Science Foundation of China under Grants 40890155, 40775051 and U0733002 Project KZCX2-YW-220 CAS. S.-P supported by the U.S. National Science Foundation, Japan Agency for Ocean-Earth Science and Technology. IPRC/SOEST publication #xxx/yyy
摘 要：The correlation of Northwest （NW） Pacific climate anomalies during summer with El Nino/Southern Oscillation （ENSO） in the preceding winter strengthens in the mid-1970s and remains high since. This study investigates the hypothesis that the tropical Indian Ocean （TIO） response to ENSO is key to this interdecadal change,using a 21-member ensemble simulation with the Community Atmospheric Model version 3 （CAM3） forced by the observed history of sea surface temperature （SST） for 1950-2000. In the model hindcast, the TIO influence on the summer NW Pacific strengthens in the mid-1970s, and the strengthened TIO teleconnection coincides with an intensification of summer SST variability over the TIO. This result is corroborated by the fact the model’s skills in simulating NW Pacific climate anomalies during summer increase after the 1970s shift. During late spring to early summer, El Nino-induced TIO warming decays rapidly for the epoch prior to the 1970s shift but grows and persists through summer for the epoch after. This difference in the evolution of the TIO warming determines the strength of the TIO teleconnection to the NW Pacific in the subsequent summer. An anti-symmetric wind pattern develops in spring across the equator over the TIO, and the associated northeasterly anomalies aid the summer warming over the North Indian Ocean by opposing the prevailing southwest monsoon. In the model, this anti-symmetric, spring wind pattern is well-developed after but absent before the 1970s shift.