Processes Influencing Carbon Cycling: Observations of the Lower limb of the Antarctic Overturning (PICCOLO)

环绕南极洲大陆的广阔而遥远的海洋统称为南大洋。这一地区拥有山区海洋，冬季黑暗，强风，冰冻温度和冰的严峻环境，是全球海洋中最少探索和观察的地区之一。然而，由于这些极端情况，它在地球气候系统中发挥着巨大且尚未量化的作用。在这个区域，大量的热量和二氧化碳在大气和海洋之间交换。控制这些大气-海洋交换的物理机制是NERC ORCHESTRA方案的主题。我们建议在PICCOLO内专注于化学和生物学在这些交流中发挥的作用。特别是，PICCOLO将专注于了解海水中所含碳的转化机制，因为它上升到南极洲附近的表面，与大气，冰，浮游植物和浮游动物相互作用居住在近表面，然后下降到海洋深处。PICCOLO将对靠近南极洲的地区进行海洋研究考察，因为计算机模型和卫星图像显示，这些地区对碳过程至关重要。这些地区的海水结冰会将盐释放到下面的水中，使其密度增加，从而导致下沉。强风导致海冰被推离南极海岸线，留下被称为冰穴的开放水域。在冰穴中，夏季的水有足够的光照，使浮游植物生长，并提供密集的沃茨，这些海水沉入深海，形成一条巨大的海洋传送带，对地球的气候系统产生巨大影响。PICCOLO团队将测量控制该地区生物和化学过程的关键变量，包括铁、营养物质、浮游植物和浮游动物。至关重要的是，研究小组将研究这个生物和化学系统不同部分之间的控制速率项。PICCOLO团队将利用最新技术，包括自主潜艇、滑翔机和浮子，在海冰下等其他无法进入和以前未研究的区域观察这些过程。最雄心勃勃的是，我们将把一艘潜艇锚在冰穴内的海床上，让它在一个冬季收集数据，第二年春天再将其回收。PICCOLO团队将在海豹身上安装仪器，这些仪器将在海豹在水中上下潜水时不断获取数据，并通过卫星通信链路实时将数据发回给科学家。PICCOLO团队将使用最先进的计算机模型分析这些丰富的新数据，以测试我们关于整个复杂的物理，化学和生物过程如何影响碳的想法。从概念上讲，我们将通过系统跟踪一个假想的水包裹，观察大气和海洋之间的过程，表层的生物过程，上层和下层海洋之间的交换以及碳的最终命运。PICCOLO假说涉及以下方面：㈠控制海洋和大气之间二氧化碳交换的因素以及紫外线在控制海水中二氧化碳浓度方面的作用; ㈡光、铁和营养物在水中浮游生物如何处理碳方面的作用; ㈢控制海洋上层向深海输出碳的中介过程; ㈣在碳全球旅程的下一阶段将其带入深海的过程。

The vast, remote seas which surround the continent of Antarctica are collectively known as the Southern Ocean. This region with its severe environment of mountainous seas, winter darkness, strong winds, freezing temperatures and ice is unsurprisingly one of the least explored and under-observed parts of the global ocean. However, because of these extremes, it plays a large and still unquantified role in Earth's climate system. In this region, large amounts of heat and carbon dioxide are exchanged between the atmosphere and the ocean. The physical mechanisms controlling these atmosphere-ocean exchanges are the subject of the NERC ORCHESTRA programme. We propose within PICCOLO to concentrate on the role that chemistry and biology play within those exchanges. In particular, PICCOLO will focus on understanding the mechanisms that transform the carbon contained in the seawater as it rises to the surface near Antarctica, interacts with the atmosphere, ice, phytoplankton and zooplankton inhabiting the near surface, before descending to the ocean depths. PICCOLO will undertake an ocean research expedition to the region close to Antarctica, as computer models and satellite images show that these are areas crucial for carbon processes. Freezing seawater in these regions releases salt into the water below, making it denser and therefore causing it to sink. Strong winds cause the sea ice to be pushed away from the Antarctic coastline, leaving areas of open water called polynyas. Within the polynyas the water has enough light during the summer to allow phytoplankton to grow, as well as providing dense waters which sink to the deep, driving a giant ocean conveyor belt which has a large impact upon Earth's climate system. The PICCOLO team will measure the key variables that control the biological and chemical processes in this region including iron, nutrients, phytoplankton and zooplankton. Crucially the team will study the controlling rate terms between different parts of this biological and chemical system. The PICCOLO team will make use of the latest technologies, including autonomous submarines, gliders and floats, to observe these processes in otherwise inaccessible and previously unstudied areas such as under the sea ice. Most ambitiously we will anchor a submarine to the seabed within a polynya and leave it over a winter season to collect data, recovering it the following spring. The PICCOLO team will put instruments on seals which will continuously take data as they dive up and down through the water, sending it back to scientists in real-time via satellite communication links. This wealth of novel data will be analysed by the PICCOLO team, using state of the art computer models, to test our ideas about how the whole complex set of physical, chemical and biological processes affects carbon. Conceptually we will follow an imaginary parcel of water through the system looking at processes between the atmosphere and ocean, biological processes in the surface layer, exchanges between the upper and lower ocean and the final fate of the carbon. The PICCOLO hypotheses address the following: (i) Factors controlling the exchange of carbon dioxide between the ocean and atmosphere and the role of ultra-violet light in controlling the concentration of carbon dioxide in seawater;(ii) The role of light, iron and nutrients in how carbon is processed by the plankton in the water; (iii) The mediating processes governing the export of carbon from the upper ocean to depth;(iv) The processes that take the carbon into the deep ocean on the next stage of its global journey.