The role of bottom boundary turbulence for the transport of tracers in marine basins (ROBOTRACE)

本提案的主要目标是确定，分析和量化的物理过程，有助于溶解物质之间的交换沉积物-水界面，湍流BBL（底部边界层），和弱湍流内部的分层盆地。重点将是倾斜地形的影响，在那里的交换是复杂的BBL restratification，BBL湍流，和次中尺度过程，被假定为确定BBL和内部之间的流体横向交换之间的相互作用。本文将采用实验和数值模拟相结合的方法来研究这些过程。更具体地说，该项目将侧重于氧和硫化物的沉积物-水交换过程，这将通过涡流相关和微剖面系统进行现场测量。这些测量将伴随一套标准海洋学仪器以及基于船舶和系泊的湍流测量，创建一个新的数据集，包括（A）氧/硫化物的沉积物-水通量和（B）BBL和内部水柱内的湍流测量。除了现场测量外，还将根据简化沉积物模型的实施情况，结合沉积物-水界面迁移过程的参数化，进行数值调查。该模型将用于理想化的一维参数研究，以及在一个二维的BBL交换设置在一个倾斜的地形。还将建立波罗的海中部的一个完全三维的现实模型，并用于研究三维特征作为氧气/硫化物运输的涡流的作用。

The main objective of this proposal is to identify, analyse, and quantify the physical processes contributing to the exchange of dissolved substances between the sediment-water interface, the turbulent BBL (bottom boundary layer), and the weakly turbulent interior of stratified basins. The focus will be on the effect of sloping topography, where the exchange is complicated by the interplay between BBL restratification, BBL turbulence, and sub-mesoscale processes that are assumed to determine the lateral exchange of fluid between the BBL and the interior. These processes will be investigated here with a combined experimental and numerical modelling approach. More specifically, the project will focus on the sediment-water exchange processes of oxygen and sulphide, which will be measured in situ by an eddy-correlation and a microprofiling system. These measurements will be accompanied by a set of standard oceanographic instrumentation as well as ship- and mooring-based turbulent measurements, creating a novel dataset of (A) sediment-water fluxes of oxygen/sulphide with (B) turbulence measurements within the BBL and the interior water column. In addition to the in situ measurements a numerical investigation will be based on an implementation of a simplified sediment model in combination with a parameterisation of the transport processes across the sediment-water interface. This model will be used in idealised one-dimensional parameter studies as well as in a two-dimensional BBL exchange setup at a sloping topography. Also a fully three-dimensional realistic model of the central Baltic Sea will be setup and used to investigate the role of three-dimensional features as eddies on the transport of oxygen/sulphide.