澳大利亚越赤道气流年代际变化对厄尔尼诺时空变异特征的影响

厄尔尼诺异常暖海温空间分布形态呈现显著的年代际变化，该时空变异特征与热带－热带外海洋大气过程密切相关。然而，我们仍需深入理解热带外气候信号对厄尔尼诺时空变异的影响，尤其是南半球年代际气候变率。澳大利亚越赤道气流是南半球热带－热带外过程的关键纽带。在年际尺度上它对厄尔尼诺有重要影响，但其年代际变化对厄尔尼诺时空变异的贡献尚不清楚。因此，本项目将对多源资料进行统计和诊断分析，以“澳大利亚越赤道气流”为切入点，“由现象到机制”开展“南太平洋热带外信号影响厄尔尼诺时空变异特征”的气候动力学研究，包括：1）阐明澳大利亚越赤道气流年代际变化规律及其与厄尔尼诺时空变异的关系；2）揭示澳大利亚越赤道气流年代际变化调制热带太平洋气候背景转变以及厄尔尼诺时空变异的物理机制。项目成果有助于提升对厄尔尼诺时空变异机理的认识和气候预测的准确性，具有重要科学意义。

El Niño has manifested itself in diversity of spatial patterns in the recent decades, referring to as El Niño spatiotemporal variation. This spatiotemporal modulation can be partly attributed to interdecadal changes in tropical-extratropical interactions. However, the associated dynamics should be further investigated, especially in the Southern Hemisphere. Australian cross-equatorial flow (CEF) is an important link between the tropics and Southern Hemisphere extratropics, which can significantly affect El Niño events on interannual timescale. But its influence on El Niño spatiotemporal variation is still unclear. By taking the long-term change of CEF into consideration, this project will investigate the impact of South Pacific extratropical climate signals on the El Niño spatiotemporal variation. The result will help to better understand the tropical-extratropical dynamics associated with ENSO spatiotemporal variation. With applications of statistical and diagnostic analysis methods, we will take advantage of various reanalysis datasets and focus on the following issues: .(1).What is the main characteristic of the interdecadal variability of the CEF? How does it relate to other Southern Hemisphere extratropical climate signals?.(2).How does the CEF modulate the El Niño diversity on interdecadal timescale? What are the associated tropical-extratropical interactive processes?