Physical and Biological Controls of CO2 Levels in the Southern Ocean: A Multi-Tracer Approach

9530824码头本研究项目是美国联合全球海洋通量研究(JGOFS)南大洋方案的一部分，旨在(1)更好地了解南大洋有机和无机碳的通量，(2)确定调节这些通量的大小和变化的物理、生态和生物地球化学因素和过程，以及(3)将这些通量置于当代全球碳循环的背景下。这项工作是在南大洋实验中合作的44个项目之一，该实验是南极极地锋区以南的一项为期三年的努力，目的是追踪碳通过有机和无机路径从空气-海洋界面通过整个水柱进入海底沉积物的流动。实验将利用两艘船，RVIB纳撒尼尔·B·帕尔默号和R/V汤普森号。海洋模型表明，南大洋是海洋吸收人类活动产生的二氧化碳的重要区域。然而，几乎没有数据来证实这些模型的预测。南大洋的三个特征可能对该区域作为二氧化碳汇的强度产生重大影响：深水上涌关闭海面，高风速导致海-气热量和气体的快速交换，以及生物生产力在开阔海洋和冰缘都发生。这三个过程之间的相互作用控制着地表二氧化碳浓度，从而控制着海气交换的方向和大小。该项目将结合化学测量和风力驱动的环流模型，确定该地区深水上升流如何与表层交换二氧化碳，以及海气交换和生物生产力如何抵消上升流对地表二氧化碳水平的影响。测量和模拟活动将定量解释南大洋二氧化碳的海气通量如何受到环流、气体交换和生物生产力的影响。模型结果将被用来预测海洋表面二氧化碳水平和溶解的无机碳库中碳同位素的比率如何响应不同大气条件引起的环流速度和路径的变化。这些结果将有助于重建以海洋沉积物和大陆冰芯的替代测量为基础的南大洋二氧化碳水平的过去状况。***

9530824 Quay This research project is part of the US Joint Global Ocean Flux Study (JGOFS) Southern Ocean Program aimed at (1) a better understanding of the fluxes of carbon, both organic and inorganic, in the Southern Ocean, (2) identifying the physical, ecological and biogeochemical factors and processes which regulate the magnitude and variability of these fluxes, and (3) placing these fluxes into the context of the contemporary global carbon cycle. This work is one of forty-four projects that are collaborating in the Southern Ocean Experiment, a threeyear effort south of the Antarctic Polar Frontal Zone to track the flow of carbon through its organic and inorganic pathways from the air-ocean interface through the entire water column into the bottom sediment. The experiment will make use of two ships, the RVIB Nathaniel B. Palmer and the R/V Thompson. The Southern Ocean has been implicated, by ocean models, as an important region of oceanic uptake of anthropogenically produced carbon dioxide. There is however, little data to corroborate these model predictions. There are three characteristics of the Southern Ocean that likely have a major impact on the strength of this region as a carbon dioxide sink: deep waters upwell close the surface, high wind speeds cause rapid air-sea exchange of heat and gases, and biological productivity occurs both in the open ocean and at the ice edge. The interplay between these three processes controls the surface carbon dioxide concentrations and thus the direction and magnitude of air- sea gas exchange. This project will use a combination of chemical measurements and a wind-driven circulation model to determine how deep water upwelling in this region exchanges carbon dioxide with the surface layer, and how air-sea exchange and biological productivity offset the effects of upwelling on the surface carbon dioxide levels. The measurement and modeling activities will yield a quantitative explan ation of how the air-sea flux of carbon dioxide in the Southern Ocean is affected by circulation, gas exchange and biological productivity. The model results will be used to predict how the surface carbon dioxide levels and the ratio of carbon isotopes in the dissolved inorganic carbon pool of the ocean respond to changes in circulation rates and pathways caused by different atmospheric conditions. These results will help reconstructions of past conditions of CO2 levels in the Southern Ocean that are based on proxy measurements in marine sediments and continental ice cores. ***