菲律宾海深层和底层环流的诊断与机制分析

As connecting the tropical and subtropical ocean circulations, the Pacific low latitude west boundary currents in the Philippine Sea play a very important role in the meridional transport of mass, heat and salt in the world ocean. Previous scientists focus on the spatial and temporal characteristics of the upper-layer Philippine Sea circulation as well as its mechanism. However, the studies on deep-layer and bottom circulations in the Philippine Sea are really sparse because of few observation data. Based on integrated data sets which consist of public model outputs and historical plus in-situ observation data, we will further reveal the pattern of the Philippine Sea deep and bottom circulations and their driving mechanism using diagnostic method, theoretical analysis and numerical modelling. The factors including the passage depth, the magnitude of intruding flux, mixing and the basin topography which affect the Philippine Sea deep and bottom circulations will be discussed. Our studies will further clarify the potential impact of the deep Pacific west boundary current on the Philippine Sea deep and bottom circulations.

位于菲律宾海的低纬度西边界流是热带西太平洋环流与副热带西太平洋环流的交汇区域，对世界大洋经向质量、热量和盐量输送起着重要的作用。以往的研究侧重于该海域大洋上层风生环流特征和变异规律。由于观测资料匮乏，针对菲律宾海深层和底层环流的研究鲜有涉及。在公开模式资料、历史和现场实测资料集成基础上，本研究将借助诊断计算、简化理论分析和数值模拟手段，进一步揭示菲律宾海深层和底层环流的空间分布特征及其变异规律，探讨通道形状和通量强度、垂向混合以及海盆地形等因子对菲律宾海深层和底层环流的作用机制，阐明太平洋深层西边界流对菲律宾海深层和底层环流的潜在影响。

菲律宾海是北太平洋低纬度西边界流经过的关键区域，是热带与副热带海洋之间信号传递的关键环节，对其时空特征及变异机理的研究，对认识海洋在气候系统中的作用，具有重要的现实意义。本项目利用观测资料、模式资料等，对菲律宾海深层和底层环流进行了诊断分析、地转流计算，给出菲律宾海深层及底层环流的定量描述。通过水团分析发现菲律宾海深层水团主要为UCDW和LCDW，并详细描述了其通过雅浦海沟进入菲律宾海的分支情况。同时还发现菲律宾海深层环流存在季节变化和年际变化，在季节上，春秋两季，从雅浦海沟进入西马里亚纳海盆的海流较强，冬夏两季则较弱；在年际尺度上，菲律宾海底层水体从1990s到2010s增暖了0.002-0.01°C。利用多个航次的现场观测资料，分析了菲律宾海上游毗邻海域雅浦-马里亚纳海沟通道、马里亚纳海沟深层环流结构，计算了通道的输运量，并指出通道的环流结构和输运量对菲律宾海深层环流存在较大影响。利用数值模拟和模式资料分析了菲律宾黑潮上游流量与吕宋海峡输运量的关系，探讨反气旋涡与黑潮相互作用。通过本项目的实施，加深了对菲律宾海深层和底层环流的认识