Polar Sea Convective Instabilities

这项为期四年的研究的主要科学目标是了解海洋混合层-冰系统对大气风暴通过的响应。北极最强烈的地表冷却和风应力与这些风暴有关，如果不考虑以下因素，就无法预测它们对北冰洋热量和水收支的长期累积影响：(i)现实的混合层物理，（ii）冰热力学，（iii）三维风驱动的海洋环流。研究人员在以前的工作中表明，海洋的不稳定可能导致显著的深海对流和可能形成的底部水。触发这些不稳定性的初始能量来源可以由瞬态大气强迫提供。将开发数值模式，包括对上层海洋（温度、盐度、环流和冰）对大气风暴通过的响应的三维模拟。该数值模型将由一个具有嵌入湍流闭合混合层的现有海洋原始方程模型和一个具有真实热力学和力学性能的冰模型组成。嵌入的混合层将包括以前被忽视的物理学，以预测条件不稳定性的开始和深水的可能形成。深层对流的现实预测对于理解全球传送带的开始和海洋在气候变化中的作用是必要的。早期海洋模型的一个主要缺陷是缺乏足够的对流物理，无法真实地预测对流产生的深层水团的正确温度和盐度特性。所提出的模拟程序，包括真实的风暴强迫和真实的海洋对流，将直接将大气强迫和冰热力学与混合层动力学和格陵兰-冰岛海全球传送带的开始联系起来。这些结果将有助于在盆地和全球海洋模式中更真实地参数化亚网格尺度对流的热量、质量、动量、营养物质和示踪剂。

The major scientific objective of this proposed four-year study is to understand the coupled ocean mixed layer-ice system response to the passage of atmospheric storms. The most intense surface cooling and wind stresses in the Arctic are associated with these storms, and their long-term cumulative effects on the heat and water budgets for the Arctic Ocean cannot be predicted without including (i) realistic mixed layer physics, (ii) ice thermodynamics, and (iii) three-dimensional wind-driven ocean circulation. The investigator has shown in previous work that oceanic instabilities may lead to significant deep oceanic convection and possible formation of bottom water. The initial energy source to trigger these instabilities may be provided by transient atmospheric forcing. Numerical models will be developed including a three-dimensional simulation of the upper ocean (temperature, salinity, circulation, and ice) response to passage of atmospheric storms. This numerical model will consist of an existing ocean primitive equation model with embedded turbulence-closure mixed layer and an ice model with realistic thermodynamics and mechanical properties. The embedded mixed layer will include previously-neglected physics to predict the onset of conditional instabilities and possible formation of deep water. The realistic prediction of deep convection is necessary to understand the start of the global conveyor belt and the role of the oceans in climate change. A major deficiency in earlier ocean models has been the lack of adequate convection physics to realistically predict the correct temperature and salinity properties for the convectively-produced deeper water masses. The proposed modeling program, including realistic storm forcing and realistic ocean convection will directly tie atmospheric forcing and ice thermodynamics to mixed layer dynamics and the start of the global conveyor belt in the Greenland-Iceland Seas. The results will lead to more realistic parameterization of subgri d scale convection of heat, mass, momentum, nutrients and tracers in basin and global oceanic models.