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本文首先指出北太平洋副热带中部模态水(简称中部模态水)的形成具有显著的“局地”特征,其形成海区在(165°E~160°W,38°N~42°N)区间.海气通量分析表明单纯的外部大气强迫场(太阳短波辐射、净热通量和风应力旋度)不能解释中部模态水形成海区的“局地”性;进一步对上层海洋层结季节变化特征的分析发现秋季(9~10月)在北太平洋中部上层海洋(<75m)(165°E~160°W,38°N~42°N)区间存在特殊的浮力频率低值区——层结稳定性“豁口”.该层结稳定性“豁口”作为“预条件(Precondition Mechanism)”机制对中部模态水形成的“局地”特征给出了合理的解释.在上述研究的基础上,基于一个上层海洋混合层热平衡方程,通过诊断分析揭示该层结稳定性“豁口”是由海表热力强迫、垂向挟卷、Ekman平流和地转平流效应共同导致的,“豁口”东、西边界的确定直接或间接地取决于海表热力强迫、Ekman冷平流和地转暖平流的纬向分布差异.
This paper first points out that the formation of the central North Pacific sub-tropical central modal water (hereinafter referred to as the central mode water) has a significant “local ” feature. The formation of the sea area ranges from (165 ° E to 160 ° W, 38 ° N to 42 ° N ) .Analysis of air-sea fluxes shows that simple external atmospheric forced fields (solar shortwave radiation, net heat flux and wind stress curl) can not explain the “local” nature of the central modal water-forming sea area; further analysis of the upper ocean The analysis of seasonal variation of the stratigraphy shows that there is a special low buoyancy frequency in the autumn (September-October) in the upper North Pacific Ocean (<75m) (165 ° E ~ 160 ° W, 38 ° N ~ 42 ° N) Zone stability of stratum “stoichiometry ” The stratum “stomatal stability ” notch “as ” Precondition Mechanism “mechanism to Based on the above studies, based on a heat balance equation of the upper ocean mixed layer, the stability of the layer is revealed through the diagnostic analysis. The ”gap“ is formed by sea surface thermal force, vertical entrapment, Ekman advection And earth-advection parallel effects, the determination of the ”east-west boundary“ of ”gap " depends directly or indirectly on the thermal force of sea surface, Ekm an The latitudinal distribution difference of cold advection and warm-warm advection.