Collaborative Research: Carbon Levels at the Arctic Salinity-Stratified Sea Ice Edge (CLASSSIE)

第一部分：北冰洋覆盖着北极，每年冬天北冰洋表面都会结冰，海冰厚度可达1-3米。当海水结冰时，冰会排出盐分，因此冰层主要由淡水组成。因此，当海冰在夏天融化时，它会产生一层薄薄的淡水层，漂浮在下面较咸的海水上。传统的海洋测量很少测量这个新鲜的海层，因为船只通常从大约5米深的深度收集数据。然而，这些淡水透镜可能会对大气-海洋气体交换发挥关键作用，包括二氧化碳，二氧化碳是导致全球变暖的主要气体，北冰洋夏季海冰覆盖的近一半消失。北冰洋被认为吸收了大约10%的人类二氧化碳排放。尽管如此，这个数字是高度不确定的，部分原因是在表面观察的稀少。该项目旨在通过在科考船和名为Wave Glider的自主水面平台上对波弗特海的淡水层进行采样来解决这一不确定性来源。我们将把淡水层的化学成分与其正下方的咸水进行比较，并利用这些数据来修正对整个北极地区二氧化碳吸收的估计，这些影响以前从未测量过，北极经历了季节性的海冰融化，面积高达德克萨斯州的2.5倍。对海洋碳吸收的更好估计有助于我们更好地了解全球碳预算，并监测减缓气候变化的努力。项目科学家将培训一名博士生，并与乌里大学梅特卡夫研究所的科学传播专家合作，通过一系列网络研讨会让记者和公众参与北冰洋科学。第二部分：北冰洋约占人类排放二氧化碳的10%，这有助于减少气候变化的影响。然而，我们对北冰洋碳汇的了解是不确定的，因为观测的数量以及它们是如何收集的。北极变暖的速度比地球上其他任何地方都快，导致海冰覆盖面积发生了戏剧性的变化。消退的海冰留下的更新鲜的融水层通常持续1到5周。它的二氧化碳水平与只有几米深的水中的二氧化碳水平不同，在那里，船只通常会根据进水口的位置进行采样。由于海洋对碳的吸收是由海洋表面的二氧化碳水平决定的，因此融化水与通常由船只采样的二氧化碳之间的差异需要对这些基于船舶的测量进行修正。这一修正将影响北冰洋季节性无冰区域的碳汇，覆盖面积为0.35至175万平方公里(面积比德克萨斯州大2.5倍)。北冰洋盐度-层化海冰边缘碳汇(CLASSSIE)是一个测量波弗特海边缘冰区关键碳系统参数的项目。该项目将与NASA物理海洋学项目资助的科学家合作，开展一个名为海冰边缘盐度和层化(SASSIE)的项目。Sassie将包括一艘船和名为波浪滑翔机的自动水面飞行器的测量结果。CLASSSIE将从船上测量融水层和融水层下的碳含量，并从其中一个波浪滑翔机进行同样的测量。根据这些测量，CLASSSIE将确定有融水输入的海洋的盐度和二氧化碳水平之间的关系。利用盐度和二氧化碳水平之间的经验关系，将建议对融水层进行修正，并将其与计算机模型的融水层统计数据结合起来，生成修改后的北冰洋二氧化碳水平地图。最后，将使用修改后的地图创建对北冰洋碳汇的修订估计。改进对北冰洋碳汇的估计将有助于限制全球碳预算，这对监测气候变化缓解至关重要。该项目将培养一名博士生。CLASSSIE还将与位于URI的梅特卡夫研究所合作，开发一个由四部分组成的网络研讨会系列，以吸引记者、公众观众和感兴趣的研究人员参与北冰洋科学。这一奖项反映了NSF的法定使命，并通过使用基金会的学术价值和更广泛的影响审查标准进行评估，被认为值得支持。

Part 1:The Arctic Ocean covers the North Pole and its surface is frozen each winter with a layer of sea ice that can be 1-3 meters thick. When seawater freezes, the ice expels the salt so that the layer of ice is composed mostly of freshwater. Therefore, when the sea ice melts in summer, it creates a thin layer of freshwater that floats on the saltier seawater beneath it. Traditional oceanographic measurements rarely measure this fresh layer because ships typically collect data from a depth of about 5 m. Yet, these freshwater lenses may play a key role influencing the atmosphere-ocean exchange of gases, including carbon dioxide, the principal gas responsible for global warming and the loss of nearly half of the summertime sea ice coverage of the Arctic Ocean. The Arctic Ocean is thought to absorb about 10% of the human emissions of carbon dioxide. Still, this number is highly uncertain, owing partly to the scarcity of observations at the very surface. This project aims to address that source of uncertainty by sampling the freshwater layer in the Beaufort Sea, both aboard a Research Vessel and on an autonomous surface platform called Wave Glider. We will compare the chemistry of the fresh layer to the saltier water just beneath it and use these data to correct estimates of carbon dioxide uptake for this previously-unmeasured impact across the entire portion of the Arctic that experiences seasonal sea ice melt, an area up to 2.5 times the size of Texas. Better estimates of ocean carbon uptake help us better understand the global carbon budget and monitor efforts to slow climate change. Project scientists will train a Ph.D. student and work with science communication experts at URI’s Metcalf Institute to engage journalists and public audiences in Arctic Ocean science through a webinar series.Part 2:The Arctic Ocean takes up about 10% of the carbon dioxide that humans emit, which helps diminish the effects of climate change. However, our knowledge about the Arctic Ocean carbon sink is uncertain due to the number of observations and how they are collected. The Arctic is warming faster than anywhere else on Earth, leading to dramatic changes in sea ice cover. The fresher meltwater layer left behind by the retreating sea ice typically lasts for 1 to 5 weeks. It has different carbon dioxide levels than the water just a few meters deeper, where ships generally have sampled due to the locations of their water intakes. Because the uptake of carbon by the ocean is determined by the carbon dioxide levels right at the surface, this difference between the meltwater and what is typically sampled by ships requires a correction to these ship-based measurements. This correction will affect the carbon sink over an area of the seasonally ice-free Arctic Ocean covering 0.35 to 1.75 million km2 (an area up to 2.5 times larger than Texas).Carbon Levels at the Arctic Salinity–Stratified Sea Ice Edge (CLASSSIE) is a project to measure key carbon system parameters in the marginal ice zone of the Beaufort Sea. The project will collaborate with scientists funded by the NASA Physical Oceanography program in a project called Salinity and Stratification at the Sea Ice Edge (SASSIE). SASSIE will include measurements from a ship and autonomous surface vehicles called Wave Gliders. CLASSSIE will make carbon measurements in and under the meltwater layer from the ship and do the same from one of the Wave Gliders. From these measurements, CLASSSIE will determine a relationship between salinity and carbon dioxide levels for an ocean with meltwater input. Using that empirical relationship between salinity and carbon dioxide levels, a correction in the meltwater layer will be proposed and combined with meltwater layer statistics from a computer model to produce a modified map of Arctic Ocean carbon dioxide levels. Finally, a revised estimate of the Arctic Ocean carbon sink will be created with the modified map. Refining estimates of the Arctic Ocean carbon sink will help constrain the global carbon budget, which is crucial to monitoring climate change mitigation. The project will train a Ph.D. student. CLASSSIE will also work with the Metcalf Institute at URI to develop a four-part webinar series to engage journalists, public audiences, and interested researchers in Arctic Ocean science.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.