Turbulence, mixing and biological feedbacks in the ocean mixed layer and their relevence to the coupled ocean-atmosphere system

海洋混合层中的湍流、混合和生物反馈及其与海洋-大气耦合系统的相关性

• 批准号: NE/D01073X/1
• 负责人: Stephen Belcher
• 金额: $ 11.97万
• 依托单位: University of Liverpool
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2009
• 资助国家: 英国
• 起止时间: 2009 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FD01073X%2F1
• 关键词: Turbulence; mixing; biological; feedbacks; ocean

In the Tropics, the sea surface temperature (SST) plays the dominant role in determining the atmospheric circulation. As a result, small changes in SST (of about 1 degree centigrade) can have a significant impact on tropical weather and climate. The temperature profile in the upper ocean (the top hundred metres or so), and hence the SST is strongly influenced by the heat flux through the surface of the ocean, and the amount of turbulent mixing in the ocean. The amount of mixing determines the depth of the ocean column through which the surface fluxes are distributed (the mixed layer depth) and hence the rate of change of SST. The mixing in the ocean is driven primarily by the wind stress at the surface, but there are other influences, including mixing driven by surface waves. Mixing is inhibited by warmer (and therefore less dense) water lying on top of colder water, and enhanced by cold water lying on top of warm water. There are four components of the surface heat flux; heating by absorption of solar radiation, cooling (usually) by infrared radiation, wind driven evaporation and convective heat loss from the surface. Unlike the other components of the surface flux, the solar radiation is absorbed through quite a large depth of the ocean, and small amounts can even penetrate as deep as 100m. The exact profile of this heating is determined by how clear the water is, and can have a strong influence on the amount of mixing and the rate of change of SST. One of the major factors determining the clarity of the water is the amount of phytoplankton in the water. Phytoplankton are small free floating marine plants which, like land plants, absorb solar radiation and carbon dioxide to grow (given sufficient nutrients). The phytoplankton are then consumed by zooplankton (small marine animals). The plankton are the base of the marine food chain. Because the phytoplankton need sunlight to grow, their distribution in the oceans, both horizontally and vertically, depends strongly on the availability of solar radiation as well as the availability of nutrients. However, the vertical profile of the solar radiation in the upper ocean is primarily determined by the amount and vertical profile of the phytoplankton. Because the phytoplankton and the nutrients that they need for growth are free floating, the vertical distribution of plankton and nutrients is strongly determined by the mixing in the upper ocean. These strong interactions between the mixing, phytoplankton and the absorption of the solar radiation lead to the potential for complex feedbacks, which can ultimately drive variations in SST, climate and the biological productivity of the ocean. This project plans to investigate these links and the extent to which they can be reproduced in global climate models, by detailed computer modelling of the oceanic mixed layer including the phytoplankton and zooplankton and the availability of nutrients.

在热带地区，海表温度（SST）对大气环流起着决定性的作用。因此，SST的微小变化（约1摄氏度）可对热带天气和气候产生重大影响。海洋上层（最高层约100米）的温度分布，以及由此产生的SST，都受到通过海洋表面的热通量和海洋中湍流混合量的强烈影响。混合的量决定了海洋柱的深度，表面通量通过海洋柱分布（混合层深度），因此也决定了SST的变化率。海洋中的混合主要由表面的风应力驱动，但也有其他影响，包括由表面波驱动的混合。混合被较暖（因此密度较小）的水放在较冷的水上面所抑制，而被冷水放在温水上面所增强。地表热通量有四个组成部分：通过吸收太阳辐射加热，通过红外辐射冷却（通常），风驱动蒸发和地表对流热损失。与表面通量的其他成分不同，太阳辐射被海洋相当大的深度吸收，少量甚至可以穿透100米深。这种加热的确切轮廓取决于水的清澈程度，并且对混合量和SST的变化率有很大的影响。决定水的清澈度的主要因素之一是水中浮游植物的数量。浮游植物是小型自由漂浮的海洋植物，像陆地植物一样，吸收太阳辐射和二氧化碳来生长（给予足够的营养）。浮游植物然后被浮游动物（小型海洋动物）消耗。浮游生物是海洋食物链的基础。由于浮游植物需要阳光才能生长，它们在海洋中的水平和垂直分布在很大程度上取决于太阳辐射的可用性以及营养物质的可用性。然而，在海洋上层的太阳辐射的垂直分布主要是由浮游植物的数量和垂直分布。由于浮游植物和它们生长所需的营养物质是自由漂浮的，浮游生物和营养物质的垂直分布在很大程度上取决于上层海洋的混合。混合、浮游植物和太阳辐射吸收之间的这些强烈相互作用导致了复杂反馈的可能性，最终可能导致SST、气候和海洋生物生产力的变化。该项目计划通过对包括浮游植物和浮游动物在内的海洋混合层以及营养物的可获得性进行详细的计算机建模，调查这些联系以及它们在全球气候模型中重现的程度。

项目成果

Large-eddy simulation of subsurface phytoplankton dynamics: an optimum condition for chlorophyll patchiness induced by Langmuir circulations

地下浮游植物动力学的大涡模拟：朗缪尔环流引起叶绿素斑块的最佳条件

• DOI: 10.3354/meps12490
• 发表时间: 2018
• 期刊: Marine Ecology Progress Series
• 影响因子: 2.5
• 作者: Brereton A