The Arctic Ocean - Ventilation Timescales, Anthropogenic Carbon and Variability in a Changing Environment

北冰洋 - 通风时间尺度、人为碳和不断变化的环境中的变化

• 批准号: 456675218
• 负责人: Professor Dr. Werner Aeschbach
• 金额: --
• 依托单位: Forschungsbereich 2: Marine Biogeochemie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/456675218?language=en
• 关键词: Arctic; Ocean; Ventilation; Timescales; Anthropogenic

In the Arctic, climate change is most apparent. This shows for example in the strong decrease of the Arctic Ocean’s sea ice cover, which in turn influences the region’s heat balance and the circulation in the ocean and the atmosphere. The formation of deep water encompasses the transport of dissolved gases into the ocean’s interior, known as ventilation. The corresponding uptake of anthropogenic carbon, which is disproportionally large in the Arctic Ocean, acts as an important buffer for greenhouse gas emissions. Its knowledge is crucial for reliable climate scenarios.The ventilation timescales can be determined by measurements of certain tracers, which carry time information by their time dependent input function or radioactive decay. However, classical tracers such as CFC-12 and sulfurhexafluoride (SF6) as well as a series of modern, so called “Medusa Tracers” are not detectable in the deepest parts of the Arctic Ocean. The new Atom Trap Trace Analysis (ATTA) method now allows for measurements of the radioisotope 39Ar in seawater and thus for coverage of exactly the age range that could not be precisely resolved in the past. In combination with the mentioned tracers as well as radiocarbon (14C), age distribution functions and ventilation timescales can thus be determined for the entire water column. This approach is complemented by measurements of noble gases to determine saturation anomalies at the surface as well as the long-lived anthropogenic radioisotopes 236U und 129I, which act as markers of Atlantic water and enable the study of the exchange between the North Atlantic and the Arctic Ocean.In this project we will take and measure samples for all mentioned tracers during an expedition on the icebreaker ODEN in the Central Arctic Ocean in 2021. The data serve to determine model parameters of transit time distributions, which in turn provide the basis for the calculation of the water column inventory of anthropogenic carbon. The results will be compared to biogeochemical approaches and used to estimate ocean acidification rates. The complementing tracer data provide insights about the circulation in the North Atlantic realm and about processes at the ocean surface. To analyze the decadal changes expected to result from climatic effects, we will additionally analyse historic tracer data from the Arctic.Furthermore, from the combination of different innovative methods we expect important methodical insights as well as data-based boundary conditions for ocean models. The results of this project will thus make extensive contributions to an improved understanding of the circulation and ventilation of the Arctic Ocean, the carbon uptake capacity of the oceans and the consequences of the changing Arctic and global climate.

在北极，气候变化最为明显。例如，这表现在北冰洋海冰覆盖的大幅减少，这反过来又影响了该地区的热平衡以及海洋和大气的环流。深水的形成包括溶解气体进入海洋内部的运输，即通风。相应的人为碳吸收，在北冰洋中是不成比例的大，是温室气体排放的重要缓冲。它的知识对于可靠的气候情景至关重要。通风时间尺度可以通过测量某些示踪剂来确定，这些示踪剂通过其与时间相关的输入函数或放射性衰变来携带时间信息。然而，经典的示踪剂，如CFC-12和六氟化硫（SF6），以及一系列现代的，所谓的“美杜莎示踪剂”，在北冰洋的最深处是检测不到的。新的原子阱痕量分析（ATTA）方法现在可以测量海水中的放射性同位素39Ar，从而精确覆盖过去无法精确解决的年龄范围。结合上述示踪剂和放射性碳（14C），可以确定整个水柱的年龄分布函数和通风时间尺度。这种方法还辅以稀有气体的测量，以确定地表的饱和度异常，以及长寿命的人为放射性同位素236U和129I，它们作为大西洋水的标志，使研究北大西洋和北冰洋之间的交换成为可能。在这个项目中，我们将在2021年在北冰洋中部的破冰船ODEN上进行一次探险期间，对所有提到的示踪剂进行取样和测量。这些数据用于确定传输时间分布的模型参数，从而为计算水柱人为碳存量提供依据。结果将与生物地球化学方法进行比较，并用于估计海洋酸化率。补充的示踪数据提供了关于北大西洋环流和海洋表面过程的见解。为了分析预计由气候影响引起的年代际变化，我们还将分析来自北极的历史示踪剂数据。此外，从不同创新方法的结合中，我们期望得到重要的方法见解以及基于数据的海洋模型边界条件。因此，该项目的成果将为进一步了解北冰洋的环流和通风、海洋的碳吸收能力以及北极和全球气候变化的后果作出广泛贡献。