The Interannual Variability of the Brazil Current

巴西海流系统很重要，因为：（i）在表面，它携带温暖的热带水，具有强烈的涡流变化，在很大程度上影响区域天气模式;（ii）它具有独特的垂直结构，接受不同水平和纬度的几个水团的贡献;（iii）它是关闭南大西洋副热带环流的西边界流;（iv）其相对较弱的时间平均流表明其与大西洋纬向翻转环流有较强的相互作用。 很少有调查存在的巴西电流年际变化，部分原因是缺乏现场观测数据。本研究旨在通过分析大量的巴西海流直接测量数据和数值模型实验，提高对巴西海流系统的认识。 该项目包括支持一名早期职业首席研究员，指导一名博士后研究员，与巴西大学进行国际合作，以及培训大学生。本研究调查了巴西海流在年际时间尺度上的变化，及其与驱动它的大尺度机制的关系。它涉及分析水文，卫星和海洋再分析数据，并进行涡分辨模拟实验。水文数据分析将包括大量高密度断面，将研究巴西海流在不同纬度的结构、巴西海流与环流位置和强度的关系以及大规模风力的影响。 补充卫星测高和模型再分析数据将提供巴西海流平均流和涡流的准天气视图，以及Rossby波机制对海流变异的影响。将进行一项基于过程的研究，利用全球涡流允许的海洋模型模拟，以分离当地和远程风强迫的影响。这些运行将进行比较，对嵌套涡解决区域模式的西南大西洋域调查如何中尺度涡过程可能会响应和反馈的区域变化在较长的时间尺度。

The Brazil Current system is important because: (i) at the surface, it carries warm Tropical Water and has strong eddy variability, forcing in large extent regional weather patterns; (ii) it has a unique vertical structure receiving contributions from several water masses at different levels and latitudes; (iii) it is a western boundary current that closes the South Atlantic subtropical gyre; and (iv) its relative weak time-mean flow indicates strong interactions with the Atlantic meridional overturning circulation. Few investigations exist of the Brazil Current interannual variability, in part because of a lack of in-situ observational data. This study aims at improving the understanding of the Brazil Current system using analysis of a large collection of direct measurements of the Brazil Current and numerical model experiments. The project includes support for an early career principal investigator, mentoring of a postdoctoral researcher, international collaborations with Brazilian universities, and training of college students.This study investigates the variability of the Brazil Current on interannual timescales, and its relationship to the large-scale mechanisms that drive it. It involves analyzing hydrographic, satellite, and ocean reanalysis data, and performing eddy-resolving modeling experiments. The hydrographic data analysis, which will include a large number of high-density transects, will examine the structure of the Brazil Current at different latitudes, the relationship of the Brazil Current with the location and strength of the gyre, and the effect of the large-scale wind forcing. Complementary satellite altimetry and model reanalysis data will provide a quasi-synoptic view of the mean and eddy flow of the Brazil Current, as well as the impact of Rossby wave mechanisms on the current variability. A process-based study using global eddy-permitting ocean model simulations will be performed for separating the influence of local and remote wind forcing. These runs will be compared against a nested eddy-resolving regional model of the western South Atlantic domain to investigate how the mesoscale eddy processes may respond to and feedback on the regional variability at longer timescales.