海南岛西岸上升流与暖池的数值研究

Numerical Study on the Upwelling and Warm Pool off the Western Coast of Hainan Island

关键词:  海南岛西岸  上升流  暖池  数值模型(POM)  敏感性实验

Key words:  western coast of Hainan Island  upwelling  warm pool  numerical model (POM)  sensitive experiements

摘要:

[目的]进一步探讨海南岛西岸的上升流与暖池的特征及生成机制。[方法]首先构建更为全面的控制模型(控制实验),包括日平均风场、热通量、侧边界通量、潮汐强迫以及河流径流等强迫场,然后在控制实验基础上,构建无潮汐强迫、无热通量强迫、无季风强迫等3个敏感性实验来分析3种强迫因子对海南岛西岸上升流与暖池的作用。[结果]夏季海南岛西岸存在上升流,该上升流受热通量和潮混合共同控制,缺乏其中任何一项上升流都会消失,而西南季风起反作用。另外,海南岛西岸在冬半年为暖池控制,秋季更为显著。东北季风引起的垂向混合与潜热通量对暖池起相当作用,ENSO事件对暖池的强度也有一定影响。[结论]控制实验结果与"908"调查结果及历史观测数据吻合较好,在流场与水团验证方面效果理想。另外,敏感性实验结果得出了比前人更完善的海南岛西岸上升流与暖池生成机制的观点。

Abstract:

[Objective] This study aims to further reveal the characteristics and formation mechanisms of the upwelling and warm pool off the western coast of Hainan Island.[Methods] The control model (control experiment)is firstly built, forced by the forcing of daily averaged wind and heat flux, river discharges, tidal harmonics, as well as the lateral flux.And then three sensitive experiments without tidal harmonics, heat flux or monsoon wind are constructed to analyze the effects of these three forcing factors on the upwelling and warm pool off the western coast of Hainan Island.[Results] The upwelling off the western coast of Hainan Island exists in summer and will disappear without the forcing of heat flux or tidal mixing, indicating the combined dominant effect of heat flux and tidal mixing on this upwelling, whereas the southwesterly wind plays the negative role.Additionally, there is a warm pool off the western coast of Hainan Island in winter boreal, and the strength of warm pool is stronger in fall than that in winter.The vertical mixing induced by northeasterly wind has the considerable effect as the latent heat flux on the warm pool, and the events of ENSO also affect the strength of warm pool.[Conclusions] The results of control model are consistent with the in situ results from project "908" and historical observation, including the current field and water mass validations, and new findings about the formation mechanisms of the upwelling and warm pool off the western coast of Hainan Island are achieved based on the sensitive experiments.