东亚夏季风的季节预测，是我国短期气候预测的核心内容和科学难题，属当代“世界气候研究计划”（WCRP）的前沿。提高东亚夏季风短期气候预测能力的关键在于弄清东亚夏季风的可预报性来源及其影响东亚夏季风变率的物理机制。已有研究表明，ENSO与北半球中高纬下垫面热力异常，是东亚夏季风季节预测的两个重要可预报性来源。mega-ENSO是最近发现的一种ENSO新模态，mega-ENSO与北半球中高纬下垫面热力异常协同影响东亚夏季风变率的机理迄今为止尚不清楚。本项目着眼于最近几十年mega-ENSO、北半球中高纬下垫面热状况与东亚夏季风联系的观测事实，研究mega-ENSO与北半球中高纬热力异常协同影响东亚夏季风变率的机理，在此基础上根据前期mega-ENSO和北半球中高纬下垫面热状况的特征信息，建立东亚夏季风季节预测的物理经验模式，通过后验预报试验以检验所提出机理的合理性。

Seasonal prediction of the East Asian summer monsoon (EASM) is a crucial and challenging issue for climate prediction in China and World Climate Research Program (WCRP). The crux of how to improve the prediction skill of the EASM is understanding the predictability sources of the EASM and associated physical mechanisms. El Nino-Southern Oscillation (ENSO) and low boundary thermal conditions in the Northern Hemisphere mid-high latitudes are two crucial predictability sources for the EASM. Mega-ENSO is a newly revealed ENSO mode. The co-mingled effects of mega-ENSO and the low boundary thermal forcings in the Northern Hemisphere mid-high latitudes on the EASM variability are yet to be understood. This project aims to analyze the statistical linkages between the EASM and the prior mega-ENSO/low boundary thermal forcings in the Northern Hemisphere mid-high latitudes, examine the potential physical mechanisms on how the latter two infuence the EASM, and establish a physical empirical prediction model for the EASM. Through hindcast with the physcial empirical model, the revealed physical mechanisms would be further verified.