西太平洋副热带高压的可预测性在1970s末前后的转变

Predictability of the western Pacific subtropical high shows significant decadal shift in the late 1970s. Our previous work found that prediction skills demonstrated by state-of-the-art coupled models improve significantly after the late 1970s.Based on this result, this proposal will investigate the features of the decadal change on the western Pacific subtropical high in the late 1970s and associated air-sea interactions. The newest multi-model prediction project of Europe Union named ENSEMBLES will be used in this work. Further analyses will focus on the influences of ENSO, tropical Indian Ocean and local air-sea interaction on this decadal change of the western Pacific subtropical high and try to illustrate the major mechanisms on the summer prediction of the western Pacific subtropical high. Considering the close relationship between the western Pacific subtropical high and the summer flood or drought disasters in our country, this work will favor for improving the seasonal prediction of East Asian summer rainfall.

与全球气候在1970s末前后的突变相一致，西太平洋副热带高压的预测效果在1970s末前后也发生了明显的转变。我们的初步分析发现，现阶段海气耦合模式对西太平洋副热带高压指数的预测效果在1970s末之后有了显著的提高。基于这一事实，本项目将利用欧洲最新的多模式预测计划（ENSEMBLES），对西太副高预测效果在1970s末转变的具体表现及相关海气相互作用进行分析，进一步探讨ENSO、热带印度洋和局地海气相互作用等不同关键影响因子对副高预测效果转变的影响，揭示影响西太副高可预测性的关键物理过程和物理机制。鉴于西太平洋副热带高压与我国夏季旱涝联系紧密，本项目的展开有利于更好地认识和预测东亚夏季降水异常。

理解近几十年西太平洋副热带高压夏季预测的转变特征，对认识和提高西太和东亚夏季风系统的季度预测有重要意义。本项目利用欧盟的多模式预测计划（ENSEMBLES）发现，现阶段海气耦合模式对西太平洋副热带高压的预测技巧表现着明显的年代际转变。预测技巧在1970s末之后有了显著的提高，在90年代初表现的更加明显。项目进一步揭示了不同热带海温特征、局地海气相互作用和中纬度环流等不同关键影响因子对副高预测效果转变的影响。研究发现，印度洋海温预测技巧的提高与1970末副高预测转变联系紧密，而海洋性大陆与赤道太平洋海温型的转变也对西太副高预测提高有重要作用。本项目的研究成果，对于认识和理解不同时间段东亚夏季风系统的季度预测技巧有指示作用，有助于进一步认识和提高我国降水预测。