DUST UP

海洋生物地球化学循环是地球系统的重要组成部分，它们是一套相互关联的物理、化学和生物过程，控制着我们的环境。生物地球化学循环不仅对海洋(其组成和其中的生命)很重要，而且对大气也很重要，特别是通过二氧化碳等温室气体和二甲基硫化物(DMS)等具有气候活性的气体。海洋生物中介的二甲基硫是大气中硫的主要自然来源。有人提出，硫的海-气循环可能通过一种涉及云形成的反馈机制来调节气候，而云的形成反过来又调节DMS的生物生产。如果我们希望能够预测气候变化，那么我们必须了解这样的反馈系统是否存在，如果存在，它的规模有多大。上层海洋中DMS的化学前体是浮游植物(微型植物)光合作用的副产品。上层海洋中浮游植物的生长受光和营养物质(氮、磷、硅酸盐和铁)的有效性控制。英国表层海洋低层大气研究(SOLAS)计划已经建立了一个野外工作计划，以调查DMS生产对这些控制因素变化的响应。这些研究的重点之一是富含铁、氮和磷的撒哈拉尘埃的作用，它有助于使热带东大西洋出现的巨大浮游生物水华得到肥沃。每年涉及约5亿吨；这一数量足以影响气候。通过部分吸收和部分反射阳光，尘埃颗粒加热空气，但冷却海洋表面。它们还促进了云的形成，云将光线反射回太空。另一个主要关注点是上升流在推动沼气浮游生产方面的作用。上升流是一种将大量营养丰富的深海冷水输送到海面的物理过程。浮游生物产量的增加是沿海地区上升流的一个众所周知的后果，例如非洲西北部海岸。我们建议使用计算机模型来模拟上层海洋中DMS的产生，以响应大气输入的铁以及来自撒哈拉沙尘和海洋上升流的营养物质。我们将构建一个非洲西北海岸和东部副热带大西洋的区域模式，并利用它来评估这些驱动因素对气候尺度上DMS通量的影响的重要性。

Oceanic biogeochemcial cycles are an important part of the earth system, these are the set of interlinked physical, chemical and biological processes that control our environment. Biogeochemical cycles are important not only in the ocean (its composition and the life within it) but also to the atmosphere, in particular through greenhouse gases such as carbon dioxide and climatically active gases such as dimethyl sulphide (DMS). Oceanic biologically mediated DMS is the dominant natural source of sulphur to the atmosphere. It has been proposed that the air-sea cycling of sulphur may regulate climate via a feed-back mechanism involving cloud formation which in turn regulates the biological produciton of DMS. If we wish to be able to predict climate change then we must understand whether such a feed-back system exists and if so, how large it is. The chemical precursors of DMS in the upper ocean are a by product of photosynthesis by phytoplankton (microscopic plants). The growth of phytoplankton in the upper ocean is controlled by the availabilty of light and nutrients (nitrogen, phsophorous, silicate and iron). The UK Surface Ocean Lower Atmosphere Study (SOLAS) program has already estabilshed a fieldwork program to investigate the response of DMS production to changes in these contolling factors. One focus of these studies is the role of iron, nitrogen and phosphorus rich Saharan dust, which helps to fertilize the huge plankton blooms that occur in the tropical eastern Atlantic. Somewhere in the region of 500 million tonnes per year is involved; an amount sufficient to affect the climate. By partly absorbing and partly reflecting sunlight, the dust particles heat the air but cool the ocean surface. They also encourage cloud formation, which reflects light back into space. Another major focus is the role of upwelling in driving planktonic production of biogases. Upwelling is a physical process which transports large quantities of cold nutrient rich deep ocean water to the surface. Enhanced planktonic production is a well known consequence of upwelling in coastal regions, such as the NW African coast. We propose to use computor models to simulate the production of DMS in the upper ocean in response to atmospheric inputs of iron, and nutrients from Saharan dust and oceanic upwelling. We will construct a regional model of the NW African coast and the eastern sub tropical Atlantic and use it to assess the significance of impacts of these drivers on DMS fluxes to the atmosphere at climate scales.