Deep Ocean Ventilation Through Antarctic Intermediate Layers (DOVETAIL)

[9528806 . smethe]拟议的项目是一项多机构综合研究的一部分，研究的是威德尔海新形成的底水流出及其向南大西洋扩散的情况。它建立在早期成功的研究基础上，这些研究包括：流入东威德尔海的中间水团，它们在威德尔环流内的改变，以及它们与西威德尔海底水形成过程的相互作用。这项研究被称为通过南极中间层的深海通风（DOVETAIL），包括六个组成部分，涉及水文测量、自然示踪剂实验和建模研究。这项研究将在威德尔海和斯科舍海在威德尔-斯科舍汇合处汇合的德雷克海峡以东的中心进行，并将与德国和西班牙的国家南极计划合作进行。这一特殊组成部分涉及作为威德尔环流水停留时间和运动的示踪剂的氟氯化碳浓度的测量。这项研究有四个相关的目标。首先是对汇合处威德尔海原水的数量和理化特性进行评价。第二是描述与威德尔-斯科舍合流内密集的南极水域扩张和下沉有关的主要过程。第三是估计世界海洋的通风率，第四是估计区域海洋运输和水文结构的季节性波动，并评估季节至年际变化对威德尔海水通风率的可能影响。深海的通风作用，即表层以下的水体上升到海面，以补充大气中的气体，并向大气释放热量，这是南极特有的现象，它通过影响全球二氧化碳的储存量，并通过调节南半球季节性海冰的数量和范围，对全球变化产生重大影响。该组件将测量三种氯氟烃（也称为氟利昂或CFC）： F-11、F-12和F-113。由于这些人为气体的大气浓度已被相当精确地追踪了近50年，它们的海洋值以及它们的比值可以用来提供精确的时间估计，自从一个给定的水样最后一次暴露在大气中以来，并推断威德尔海水团改变和混合过程的时间尺度。＊＊＊

9528806 Smethie The proposed project is part of a multi-institutional integrated study of the outflow of newly formed bottom water from the Weddell Sea and its dispersion into the South Atlantic Ocean. It builds upon earlier successful studies of the inflow of intermediate water masses into the Eastern Weddell Sea, their modification within the Weddell Gyre, and their interaction with bottom water formation processes in the western Weddell Sea. The study is called Deep Ocean Ventilation Through Antarctic Intermediate Layers (DOVETAIL) and includes six components involving hydrographic measurements, natural tracer experiments, and modeling studies. The study will be centered east of the Drake Passage where water masses from the Weddell Sea and the Scotia Sea come together in the Weddell-Scotia Confluence, and will be carried out in cooperation with the national antarctic programs of Germany and Spain. This particular component concerns the measurement of the chlorofluorocarbon concentration as a tracer of residence time and movement of Weddell Gyre water. The study has four related objectives. The first is to assess the quantity and the physical and chemical characteristics of Weddell Sea source waters for the confluence. The second is to describe the dominant processes associated with spreading and sinking of dense antarctic waters within the Weddell-Scotia Confluence. The third is to estimate the ventilation rate of the world ocean, and the fourth is to estimate seasonal fluctuations in the regional ocean transport and hydrographic structure and to assess the likely influence of seasonal to interannual variability on rates of ventilation by Weddell Sea waters. Ventilation of the deep ocean -- the rising of sub-surface water masses to the surface to be recharged with atmospheric gases and to give up heat to the atmosphere -- is a uniquely antarctic phenomenon that has significant consequences for global change by affecting the global reser voir of carbon dioxide, and by modulating the amount and extent of seasonal sea ice in the southern hemisphere. This component will make measurements of three species of chlorofluorocarbons (also known as freons or CFC's): F-11, F-12, and F-113. Since the atmospheric concentration of these anthropogenic gases has been tracked quite precisely for almost fifty years, their oceanic values, and the ratios of their values can be used to provide accurate estimates of the time since a given water sample was last exposed to the atmosphere, and to infer the time scales of water mass modification and mixing processes in the Weddell Sea. ***