Ice-Ocean interactions and the circulation of salty oceans on Icy Moons

冰-海洋相互作用和冰卫星上咸海洋的环流

• 批准号: 2599615
• 金额: --
• 依托单位: University of Reading
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2021
• 资助国家: 英国
• 起止时间: 2021 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2599615
• 关键词: Ice; Ocean; interactions; circulation; salty

The potential for life is considerably increased in the presence of liquid water, an energy source, and nutrients. There is growing evidence that some of the Icy moons of the solar system (e.g., Europa) harbor liquid oceans, putting them at the forefront of the search for extra-terrestrial life. But it remains unclear whether these oceans are salty, that is, contain potential nutrients useful for life.From a dynamical point of view, a salty ocean is expected to behave in a very differently to a freshwater ocean. This is in part due to the non-linearities of the equation of state for salty water (notably cabelling and thermobaricity). In the case of a subglacial ocean, transports of heat and freshwater/salt are also tightly coupled because of processes at the ice-ocean interface, some of which are strongly salinity-dependent (e.g., freezing point).The working hypothesis of this project is that the differences in ocean circulation due to salinity could be observable through signatures on the outer ice shell and the magnetic field, giving us a probe into the chemical composition of oceans of Icy moons and one of the conditions for life.This PhD project is a first step in this direction by addressing the following objectives:1. Clarify and quantify the differences in circulation between salty and freshwater oceans,2. Determine potential signatures of these circulations on the ice shell (e.g., rates/pattern of ice renewal)Few studies have addressed the 3-dimensional ocean circulation of the Icy moons. None has explicitly accounted for the ocean-ice interaction and a realistic representation of the coupled heat/water/salt fluxes at the ocean-ice interface. As a result, effects of salt on the 3D ocean state have not been addressed. On a shorter term than that required to evaluate the habitability of the icy moons, the present work is a step change in understanding the dynamics and evolution of these moons, eventually feeding into missions such as the ESA's Jupiter Icy Moons Explorer JUICE. The approach will combine numerical modelling with a state-of-the-art General Circulation Model and idealized theoretical models of the ocean.

在液态水、能量源和营养物质的存在下，生命的潜力大大增加。越来越多的证据表明，太阳系中的一些冰质卫星（例如，欧罗巴）拥有液态海洋，使它们处于寻找外星生命的最前沿。但目前还不清楚这些海洋是否是咸的，也就是说，是否含有对生命有用的潜在营养物质。从动力学的角度来看，咸海洋的行为与淡水海洋非常不同。这部分是由于盐水状态方程的非线性（特别是cabelling和温压性）。就冰下海洋而言，由于冰-海界面的过程，热量和淡水/盐的传输也紧密耦合，其中一些过程强烈依赖于盐度（例如，该项目的工作假设是，由于盐度的海洋环流的差异可以通过外部冰壳和磁场上的特征来观察，从而让我们探索冰卫星海洋的化学成分和生命的条件之一。这个博士项目是朝着这个方向迈出的第一步，解决了以下目标：1.澄清和量化咸水和淡水海洋之间的环流差异，2。确定冰壳上这些环流的潜在特征（例如，冰更新的速率/模式）很少有研究涉及冰卫星的三维海洋环流。没有明确占海洋-冰的相互作用和耦合的热/水/盐通量在海洋-冰界面的现实代表。因此，盐对3D海洋状态的影响尚未得到解决。在比评估冰冷卫星的可居住性所需的时间更短的时间内，目前的工作是理解这些卫星的动力学和演化的一个步骤，最终将投入到欧空局的木星冰冷卫星探测器JUICE等任务中。该方法将把联合收割机数值模型与最先进的大气环流模型和理想化的海洋理论模型结合起来。