Sea ice physical properties and their application to ocean-atmosphere interaction

长期存在的海洋-大气相互作用不能通过海冰发生的概念是无效的。我们现在知道，海冰为海洋与大气的交换，尤其是二氧化碳的交换，提供了一个不同程度的有效渠道。现在人们认为，海冰（取决于其温度）在形成或增长的过程中可能会产生二氧化碳，这些二氧化碳可能会被困在冰中，最终排放到深海中。这些相互作用受其液体和气体包裹体的形状、位置和连通性的调节，其内在性质受冰内垂直温度梯度的控制，也取决于海冰的类型和年龄。我们的目的是表征海冰中液体和气体包裹体的大小、形状、位置和连通性，以及它们从形成到融化的变化。这些结果对于确定在一个年度循环中有多少大气中的二氧化碳可能通过海冰过程或海冰过程被封存在极地海洋中至关重要。***这项工作的一个重大障碍是传统的海冰取样方法。也就是说，从更大的体积中垂直移除海冰芯，并随后将其储存在-20°C。一旦海冰样本从漂浮在海洋中的海冰中向上拉出，它就不再连接海洋和大气，而控制我们感兴趣的大部分物理现象的垂直温度梯度就会受到不可挽回的影响。这与通过向上延伸的液体通道沐浴在海水中的海冰底部特别相关。一个有用的比喻是把一块海绵从水槽里拿出来。把海绵从水槽里拿出来，切成薄片看看它含有多少水，这可能不会产生实际的结果。这个项目的首要目标是方法论的发展。海冰取芯和样本储存的局限性早已为人所知；我和我的学生们将努力采用在其他领域长期使用的现有成像技术，并开发新的最先进的方法，用于对海冰内含物的形状、位置和类型进行非侵入性测量。我们想要量化的是，当海绵在水槽中漂浮的时候，它里面有多少液体和空气，而它在水槽中漂浮的时候。这项工作将大大扩展目前关于海冰如何影响极地海洋中海洋和大气之间的生物地球化学过程和二氧化碳通量的知识。这项工作的结果将包括一个长期寻求的观测衍生的海冰渗透率数据库，该数据库按相（包括液体盐水、气体和固体盐）相对划分，用于各种海冰发展阶段，作为自然范围广泛的物理条件的函数。这些结果对于验证现有的海冰盐水保留、盐水排放和温室气体通过海冰向海洋输送的理论近似和建模至关重要。* * * * *

The long-standing concept that ocean-atmosphere interaction cannot occur through sea ice is invalid. We now understand sea ice provides a variably effective conduit for ocean-atmosphere exchange, particularly for CO2. It is now thought that sea ice (depending on its temperature) may produce CO2 as it forms or grows, which may be trapped within the ice and eventually exported to the deep ocean. These interactions are modulated by the shape, location and connectivity of its liquid and gas inclusions, the intrinsic properties of which are controlled by a vertical temperature gradient within the ice and depend also on the sea ice type and age. We aim to characterize the size, shape, location and connectedness of liquid and gas inclusions in sea ice and changes therein from formation to melting. These results are imperative in determining how much atmospheric CO2 may be sequestered in polar oceans over an annual cycle both through, and as a result of, sea ice processes.***A significant obstacle to this work is the traditional methodology for sea ice sampling. That is, the vertical removal of a sea ice core from a larger volume and its subsequent storage at -20°C. Once a sea ice core sample is pulled upward and out of sea ice floating in the ocean, it's no longer connecting the ocean and atmosphere, and the vertical temperature gradient that controls much of the physics we're interested in is irreparably affected. This is especially relevant to the bottom portion of the sea ice bathed in ocean water through liquid channels extending upward into it. A useful analogy is a sponge removed from a sink of water. Removing the sponge from the sink and slicing it up it to see how much water it contained may not yield realistic results. ***The overarching goal of this program is methodological development. The limitations of sea ice coring and sample storage have been known for a long time; my students and I will endeavour to employ existing imaging techniques long used in other areas, and develop new state-of-the-art methods for the non-invasive measurement of the shape, location and type of sea ice inclusions. We would like to quantify how much liquid and air are in the proverbial sponge when it is floating in the sink, while it is floating in the sink.***This work will greatly expand current knowledge on how sea ice affects the biogeochemical processes and CO2 fluxes between the ocean and atmosphere in polar seas. Results of this work will include a long-sought observationally-derived library of permeability data for sea ice, partitioned relatively by phase, (including liquid brine, gases and solid salts) for a variety of sea ice stages of development as a function of naturally wide ranging physical conditions. These results are vitally important for verification of existing theoretical approximations and modeling of sea ice brine retention, brine drainage and greenhouse gas transport through sea ice to the ocean below. *****