Collaborative Research: Modeling Thermobaric Effects in Antarctic Deep Ocean Convection

这个合作项目是对海洋中的温压不稳定性及其对南大洋深层对流的影响的模拟研究。温压不稳定性是指海水的可压缩性是压力的非线性函数，因此覆盖在较暖和较咸的层上的较冷和较新鲜的层可能是静态稳定的，但如果受到扰动，则会变得不稳定。人们很早就知道这在理论上是可能的，但直到最近才被认为是一种实际上可能发生在南大洋的影响，特别是可能解释了威德尔海出现Polynyas(海冰内相当大的开阔水域)的可能原因。这次对热压性对深海对流影响的评估将基于一个数值大涡模拟(LES)模式，该模式能够直接模拟对流羽流和大尺度海洋流动特征，这些特征将在强烈的热压性颠覆时被预期。基于先前在威德尔海的海洋巡航中观察到的条件而初始化和强迫的LES模式的初步结果，这项拟议的工作将把一系列精心构建的模式运行与观测相结合，以确定关键的倾覆过程。

This collaborative project is a modeling study of thermobaric instability in the ocean, and its effect on deep convection in the Southern Ocean. Thermobaric instability refers to the fact that the compressibility of sea water is a non-linear function of pressure, so that a colder and fresher layer overlying a warmer and a saltier layer may be statically stable, but become unstable if it is disturbed. That this is theoretically possible has been known for a long time, but only recently has it been considered as an effect that could actually occur in the Southern Ocean, specifically as the potential explanation of the episodic occurrence of polynyas (sizable areas of open water within the sea-ice pack) in the Weddell Sea. This evaluation of the impact of thermobaricity on deep ocean convection will be based on a numerical Large Eddy Simulation (LES) model capable of simulating directly the convection plumes and large scale oceanic flow features that would be expected with intense thermobaric overturn. Based on preliminary results of an LES model initialized and forced by conditions observed during previous oceanographic cruises to the Weddell Sea, this proposed work will combine a carefully structured series of model runs with observations to identify critical overturning processes.