SP 2.3 - Dynamics of convection linking the sea-surface microlayer (SML) with the bulk phase

SP 2.3 - 连接海面微层 (SML) 与体相的对流动力学

• 批准号: 496364617
• 负责人: Dr. Thomas Badewien
• 金额: --
• 依托单位: Institut für Chemie und Biologie des Meeres (ICBM)
• 依托单位国家: 德国
• 项目类别: Research Units
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/496364617?language=en
• 关键词: SP; 2.3; Dynamics; convection; linking

Our motivation lies in the fact that the dynamic link between the sea-surface microlayer (SML) and underlying bulk water via convection leads to heterogeneous properties of the SML. This in turn controls the extent of bio-photochemical reactions and air-sea gas fluxes. Convection is driven by evaporation, which cools the SML and makes it more saline. Consequently, the SML becomes denser, sinks, and is replaced by underlying bulk water. However, buoyancy-driven convection has been neglected in the research of the SML and air-sea gas exchange as a dynamic link between the atmosphere and the ocean. Our main objective is to obtain a mechanistic understanding of the dynamics between the SML and the near-surface layer (NSL). One of the main points of our proposal is that buoyancy-driven convection is a key component of the SML and air-sea interaction, despite its small-scaled nature. A mechanistic understanding of convection is essential, as the extent of bio-photochemical reactions and the air-sea exchange of trace gases, energy, and momentum will ultimately be determined by exchange processes between the SML and the NSL, and ultimately with deeper layers. We will develop an experimental setup with multiple profiling microelectrodes and an optical schlieren system to investigate convection under various external forcing. We will investigate the effect of horizontal flow due to gradients of surface tension (i.e. Marangoni effect). We will also participate in the BASS joint mesocosm experiment to investigate the influence of biogenic surfactants on the convective transport mechanism between the SML and the NSL. In the BASS joint field experiment, we will address the question to what extent variations of small-scaled convection are affected by the variability of sub-mesoscale (1 km–10 km) hydrodynamic processes near the ocean’s surface. We will deploy two research catamarans and a fleet of drifters equipped with conductivity and temperature sensors to investigate density anomalies between the SML and NSL. We will monitor external oceanic and atmospheric forcing to describe the density anomalies. Finally, we will use the gained knowledge from the lab experiments, mesocosm, and field study to develop a mathematical framework to describe temperature and salinity profiles, and their fluctuations under the influence of defined oceanic and atmospheric forcing.

我们的动机在于这样一个事实，即海洋表面微层(SML)与下伏的散体水之间通过对流的动态联系导致了SML的非均匀性质。这反过来又控制着生物光化学反应的程度和大气-海洋气体的通量。对流是由蒸发驱动的，蒸发使SML冷却，使其变得更咸。因此，SML变得更稠密，下沉，并被底层的散装水取代。然而，浮力驱动的对流作为连接大气和海洋的动力纽带，在SML和海-气交换的研究中一直被忽视。我们的主要目标是从机制上了解SML和近地表(NSL)之间的动力学。我们建议的要点之一是，浮力驱动的对流是SML和海-气相互作用的一个关键组成部分，尽管它的规模很小。从机理上理解对流是至关重要的，因为生物光化学反应的程度以及微量气体、能量和动量的海-气交换最终将由SML和NSL之间的交换过程决定，并最终与更深的层交换。我们将开发一个多个仿形微电极和光学纹影系统的实验装置来研究各种外力作用下的对流。我们将研究由于表面张力梯度(即Marangoni效应)而产生的水平流动的影响。我们还将参加BASS联合中温带实验，以研究生物表面活性剂对SML和NSL之间对流输送机制的影响。在BASS联合现场试验中，我们将讨论小尺度对流变化在多大程度上受到近海面亚中尺度(1公里-10公里)水动力过程的变化的影响。我们将部署两艘研究双体船和一支装有电导率和温度传感器的漂流船船队，以调查SML和NSL之间的密度异常。我们将监测外部海洋和大气强迫，以描述密度异常。最后，我们将使用从实验室实验、中观和野外研究中获得的知识来开发一个数学框架来描述温度和盐度分布，以及它们在明确的海洋和大气强迫影响下的波动。