海洋季节内变化对太平洋-印度洋贯穿流水体输运的影响

The Pacific to Indian Ocean throughflow (PIOT), which serves as the global thermohaline conveyor belt, plays an important role in the global climate system. The oceanic intraseasonal variability (ISVs) in the PIOT region are forced by both the intraseasonal oscillation of local wind and the oceanic long waves that propagating from the Indian and Pacific Oceans. These ISVs are suggested to have significant influence on the volume transport of the PIOT. Previous studies of the oceanic ISV in PIOT region mainly focus on the eastern passages, i.e. the Makassar, Lombok and Ombai straits. The oceanic ISV in the western passages of the PIOT, say in the Sunda and Karimata straits, however, has not been investigated yet. Furthermore, the mechanism of the oceanic ISV influence on the PIOT volume transports is unclear. Based on the in situ observations of currents, salinity and temperature in Sunda and Karimata straits conducted independently by our group through China-Indonesia International Corporation, the INSTANT observation, and supplemented by remote sensing and ocean reanalysis products, this project plans to reveal the feature of oceanic ISV in the PIOT region. Using high resolution numerical model, this project also plans to investigate the dynamics of the oceanic ISV and its propagation in the PIOT region, and to estimate the influences of oceanic ISV on the volume transport between the Indian and Pacific Oceans.

太平洋-印度洋贯穿流是全球热盐输送带的关键环节，在气候系统中有重要作用。受局地大气季节内振荡和来自太平洋、印度洋的大尺度海洋波动的共同强迫，该海域海洋季节内变化极为显著，并可影响贯穿流水体输运。过去的研究仅关注贯穿流东部通道，如望加锡、龙目和翁拜海峡，忽视了贯穿流西部通道巽他和卡里马塔海峡的海洋季节内变化，且海洋季节内变化影响贯穿流水体输运的过程与机制也不清楚。本项目拟利用申请人所在研究团队通过国际合作获取的巽他和卡里马塔海峡海流、温盐连续观测、国际计划INSTANT观测、卫星遥感及海洋再分析资料，通过统计分析和赤道波理论诊断，结合高分辨率数值试验，研究太平洋-印度洋贯穿流海域海洋季节内变化特征、传播过程与机制，探讨其对热带印太洋际水体输运的影响。

太平洋-印度洋贯穿流海域海洋季节内变化极为显著，并可影响贯穿流水体输运。过去的研究仅关注贯穿流东部通道，如望加锡、龙目和翁拜海峡，忽视了贯穿流西部通道巽他和卡里马塔海峡的海洋季节内变化。本项目利用申请人所在研究团队通过国际合作获取现场观测资料，结合卫星遥感和再分析资料等，对太平洋-印度洋贯穿流海域，特别针对巽他和卡里马塔海峡季节内变化特征、过程及机制进行了研究，并探讨了其对周边海域水体输运及海洋环境的影响。取得的主要科学认识有：（1）基于卫星高度计观测研究太平洋-印度洋贯穿流海域海洋季节内信号传播路径，指出其主要是第一和第二斜压模Kelvin波；（2）基于现场海流剖面连续观测，指出巽他海峡贯穿流季节内变化显著，周期约为20~45天，振幅与季节变化振幅相当，主要驱动机制为赤道Kelvin波传播和局地Ekman输运造成海峡两端海平面高度梯度异常，从而驱动沿海峡方向的季节内海流变化，导致巽他海峡贯穿流流向发生反转，并影响巽他海峡邻近海域叶绿素浓度分布；（3）太平洋-印度洋贯穿流海域海洋季节内变化存在年际差异，在北半球春季和秋季，这一年际差异分别由ENSO和IOD主导；（4）卡里马塔海峡贯穿流主要由季风驱动，季节内变化微弱。以上研究成果共发表研究论文8篇（SCI收录7篇）。