Results from 14 neutrally buoyant RAFOS floats in the western equatorial Pacific Ocean

In the western equatorial Pacific the low-salinity core of Antarctic Intermediate Water (AAIW) is found at about 800 m depth between potential density levels Sigma-theta = 27.2 and 27.3. The pathways of AAIW and the degradation of its core are studied, from the Bismarck Sea to the Caroline Basins and into the zonal equatorial current system. Both historical and new observational data, and results from numerical circulation model runs are used. The observations include hydrographic stations from German and Japanese research vessels, and Eulerian and Lagrangian current measurements. The model is the JAMSTEC high-resolution numerical model based on the Modular Ocean Model (MOM 2). The general agreement between results from the observations and from the model enables us to diagnose properties and to provide new information on the AAIW. The analysis confirms the paramount influence of topography on the spreading of the AAIW tongue north of New Guinea. […]

在西部赤道太平洋，南极次级水（AAIW）的低盐度核心位于约800米深度，介于潜在密度水平Sigma-theta = 27.2至27.3之间。本研究探讨了AAIW的传输路径及其核心的退化，范围从俾斯麦海至卡罗琳海盆，直至区域性的赤道洋流系统。研究采用了历史和新的观测数据，以及数值环流模型运行的结果。观测数据包括来自德国和日本研究船的海洋学站数据，以及欧拉型和拉格朗日型洋流测量。所使用的模型是基于模块化海洋模型（MOM 2）的JAMSTEC高分辨率数值模型。观测结果与模型结果的总体一致性，使我们能够诊断其特性，并就AAIW提供新的信息。分析证实了地形对AAIW舌部向北新几内亚扩散的至关重要作用。