Upwelling in the Atlantic sector of the Southern Ocean

上升流是决定混合层特性的重要过程。上升流还为海洋内部的气体、营养物质和其他化合物进入混合层并最终进入大气提供了一条途径。由于上升流速度很小，所以不能直接测量。最近，Rhein等人（2010）利用在赤道东大西洋发现的氦同位素不平衡来推断上升流速度、上升流速率以及混合层与海洋内部之间的垂直热通量。混合层中的不平衡是由内部的富3he水上涌引起的。剩余的3He通过热液活动进入深海。对南极环极流（ACC）和威德尔海的历史氦同位素数据的首次调查表明，混合层也富含3He，在夏季，混合层下方的水上涌提供3He。虽然从历史数据集对上升流速度的初步估计看起来很有希望，但目前的氦数据缺乏足够的分辨率来确定200-300m以上的水平和垂直He梯度，这是编制上升流速度和河床混合贡献所必需的。本文拟采用历史He数据和2010年11月- 2011年2月polpolstern巡航ant27 /2和2012年1月- 2月polpolstern巡航ANT28/3期间新的专用He数据集，计算威德尔海和ACC的上升流速度和速率，以及内部和混合层之间的热通量。该提案是“涡旋和上升流：南大洋碳收支的主要因素”小组的一部分。

Upwelling is an important process in setting the characteristic of the mixed layer. Upwelling also provides a pathway for gases, nutrients, and other compounds from the ocean’s interior into the mixed layer and ultimately into the atmosphere. Since the upwelling velocities are small, they cannot be measured directly. Recently, Rhein et al. (2010) exploited the helium isotope disequilibria found in the equatorial eastern Atlantic to infer upwelling speeds, upwelling rates, and vertical heat fluxes between the mixed layer and the ocean’s interior. The disequilibrium in the mixed layer is caused by upwelling of 3He-enriched water from the interior. The surplus 3He is introduced into the deep ocean by hydrothermal activities.A first survey of historical Helium isotope data in the Antarctic Circumpolar Current (ACC) and the Weddell Sea showed, that the mixed layer is also enriched with 3He, which in summer months is supplied by upwelling of water from below the mixed layer. Although the first estimates of upwelling velocities from the historical data set look promising, the present Helium data lack a sufficient resolution in the upper 200-300m to determine the horizontal and vertical He gradients, necessary for the compilation of the upwelling velocity and of the contribution of diapycnal mixing. Here we propose to take the historical He data, and a new dedicated He data sets to be taken in November 2010 – February 2011 during the POLARSTERN cruise ANT 27/2 and January- February 2012 during POLARSTERN cruise ANT28/3 to calculate upwelling speeds and –rates in the Weddell Sea and the ACC, as well as heat fluxes between the interior and the mixed layer.This proposal is part of the Cluster “ Eddies and Upwelling: Major Factors in the Carbon Budget ofthe Southern Ocean”