Pycnocline Mixing in Shelf Seas

大陆架海在河口和海洋之间提供了一个过渡区，在那里碳、营养物质、沉积物和污染物进行交换。欧洲西北大陆架的海流和混合以潮汐与海床的相互作用为主，约80%的区域在夏季发生密度分层。这些地区的生物初级生产水平很高。然而，在这些层状流体的关键界面上，营养物质和碳的交换很少被理解，因此在数值模型中很少被代表。该项目旨在编制世界上最大的陆架海斜流和水文测量观测数据库，并利用最先进的计算机建模和新的观测技术来调查、量化和参数化导致这一关键界面通量的物理机制和过程。特别是我们将对斜斜湍流和由剪切不稳定引起的混合有更好的理解。我们将检验这样一个假设，即这些机制，或机制之间的相互作用，将斜斜剪切驱动到超过临界阈值的水平，超过这个阈值，就会出现灾难性的稳定性损失，导致间歇性混合。将开发和测试这种混合的参数化。

The continental shelf seas provide a transition zone between estuaries and the ocean across which carbon, nutrients, sediments and contaminants are exchanged. The currents and mixing on the NW European continental shelf are dominated by the tide interacting with the sea bed, with density stratification occurring during summer months across ~80% of the region. Significant levels of biological primary production occur in these regions. However, the exchange of nutrients and carbon across these critical interfaces of stratified fluid is poorly understood and so is poorly represented in numerical models.This project aims to compile the world's largest observational data base of shelf sea pycnocline turbulence and hydrographic measurements and to exploit state-of-the-art computer modelling and new observational technology to investigate, quantify, and parameterise the physical mechanisms and processes responsible for the fluxes across this critical interface. In particular we will develop improved understanding of pycnocline turbulence and mixing promoted by shear instability. We will test the hypothesis that these mechanisms, or interaction between mechanisms, drives pycnocline shear to levels which exceed a critical threshold beyond which there is a catastrophic loss of stability resulting in episodic mixing. Parameterisations for this mixing will be developed and tested.