Upwelling in the Atlantic sector of the Southern Ocean

上升流是形成混合层特征的重要过程。上升流也为气体、营养物质和其他化合物从海洋内部进入混合层并最终进入大气提供了一条通道。由于上升流速度很小，无法直接测量。最近，Rhein等人（2010年）利用在赤道东大西洋发现的氦同位素不平衡来推断上涌速度、上涌速率和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富3 He水的上涌引起的。首次对南极绕极流和威德尔海的历史氦同位素数据的调查表明，混合层中也富含氦，夏季时，来自混合层下的上升流提供了氦。虽然从历史数据集的上升流速度的第一次估计看起来很有希望，目前的氦数据缺乏足够的分辨率，在上部200- 300米，以确定水平和垂直的He梯度，必要的汇编的上升流速度和的贡献diapycnal混合。在这里，我们建议采用历史He数据，以及在POLARSTERN巡航ANT 27/2期间于2010年11月至2011年2月和POLARSTERN巡航ANT 28/3期间于2012年1月至2月采集的新的专用He数据集，以计算威德尔海和ACC的上升流速度和上升速率，以及内部和混合层之间的热通量。该提议是“涡旋和上升流：南大洋碳收支的主要因素”项目组的一部分。

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”