Pycnocline Mixing in Shelf Seas (Pycnmix)

大陆架海洋是河口和海洋之间的过渡区，碳、营养物、沉积物和污染物在此进行交换。欧洲大陆架西北部的海流和混合主要由与海床相互作用的潮汐控制，夏季约80%的区域出现密度分层。在这些地区，生物初级生产水平很高。然而，人们对营养物和碳在分层流体的这些关键界面上的交换知之甚少，因此在数值模型中也没有得到充分的体现，本项目旨在汇编世界上最大的陆架海密度跃层湍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，并参数化的物理机制和过程负责通量通过这个关键的界面。特别是，我们将提高对密度跃层湍流和剪切不稳定性促进的混合的理解。我们将测试的假设，这些机制，或机制之间的相互作用，驱动密度跃层剪切的水平超过一个临界阈值，超过该阈值有一个灾难性的损失，导致在幕式混合的稳定性。将制定和测试这种混合的参数。

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.