RAPID: Microstructure Observations of Rapid Surface Freshening in the Labrador Sea

RAPID：拉布拉多海表面快速清新的微观结构观测

• 批准号: 1036097
• 负责人: Jonathan Lilly
• 金额: $ 10.66万
• 依托单位: NorthWest Research Associates, Incorporated
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-05-01 至 2011-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1036097&HistoricalAwards=false
• 关键词: RAPID; Microstructure; Observations; Rapid; Surface

A longstanding mystery in deep convection regions concerns the rapid surface capping after deep convection. In the Labrador Sea, this capping takes the form of a thin freshwater layer, regularly seen across the entire 600 km diameter basin in April or May shortly after the deepest convection in March. This freshwater appears to have been imported from the boundary currents at the basin's periphery, but Ekman transport distributed over the 30 m mixed layer would be far too slow. Since models of overturning circulation variability frequently begin with a freshwater perturbation over the deep water formation region, the mechanism for transporting boundary freshwater to the convected interior is an important link in the climate system.The origin of the rapid freshwater capping will be investigated during the spring 2010 hydrographic cruise across the Labrador Sea by the Bedford Institute of Oceanography (BIO). A novel measurement platform, the Air-Sea Interaction Profiler (ASIP) developed by Brian Ward of the University of Galway, will be used. This upward-profiling autonomous instrument records microstructure temperature and conductivity as well as turbulent shear, and in particular resolves the uppermost centimeters of the ocean including the centimeter scale salinity skin layer. Repeated measurements will give an indication of the spatial and temporal variability with far greater resolution than the roughly 50 km CTD station spacing. Microstructure shear measurements would help quantify the turbulent mixing within the halocline and therefore shed light on its formation. Different lateral flux processes could be distinguished by their degree of vertical and horizontal homogeneity and by the associated levels of mixing activity. This untethered instrument will sample the upper ten meters which are normally contaminated by the ship wake in the CTD stations.The intellectual merit of this project is an improved understanding of freshwater transport and halocline formation in the deep convecting region of the Labrador Sea, one of the key regions in the Atlantic Meridional Overturning Circulation. The primary broader impact is the relevance this work has for our understanding of climate variability, in particular, the sensitivity of the overturning circulation to freshwater perturbations. A post-doc will received training in making at sea measurements in a multi-national project.

深度对流区域中的一个长期谜团涉及深度对流后的迅速表面上限。在拉布拉多海，该封顶采用了薄薄的淡水层的形式，在四月或3月对流最深的对流后不久，经常在整个600公里的盆地上经常看到。这种淡水似乎是从盆地外围的边界电流进口的，但是分布在30 m混合层上的Ekman运输太慢了。由于倾覆循环变异性的模型经常始于深水形成区域的淡水扰动，因此将淡水运输到对流内部的机制是气候系统的重要联系。快速淡水封盖的起源将在2010年春季的水文巡游中，由贝德福德研究所（Bedford Institute of Oceanagraphy）（Bio）（Bio）（Bio）（Bio）进行。戈尔韦大学的布莱恩·沃德（Brian Ward）开发的一个新颖的测量平台，是空气交互作用者（ASIP）。这种向上的自主仪器记录了微观结构温度和电导率以及湍流剪切，尤其是解决了海洋上最高的海洋，包括厘米尺度的盐度皮肤层。重复测量将显示出比大约50 km CTD站间距更大的空间和时间变异性。微结构剪切测量将有助于量化卤素内的湍流混合，因此阐明了其形成。不同的侧向过程可以通过其垂直和水平均匀性的程度以及混合活性的相关水平来区分。这种不受束缚的仪器将采样通常被CTD站中船只尾流污染的上米，该项目的智力优点是对拉布拉多海深对流区域的淡水运输和卤素形成的理解，这是拉布拉多海的深入对流，这是大西洋集星上的推翻循环中的关键区域之一。最广泛的影响是这项工作对我们对气候变异性的理解的相关性，尤其是推翻循环对淡水扰动的敏感性。大多数人将在一个跨国项目的海上测量中接受培训。