Antarctic Deep Water Rates of Export (ANDREX)

地球的气候正在变化，就像它过去所做的那样。当今科学家面临的一大挑战是了解这些变化的原因和后果。许多科学家寻求这一理解的方法是运行基于计算机的气候模拟，模拟海洋、大气、冰和生物之间的复杂相互作用，这些生物被认为是推动气候变化的原因。部分得益于这些模拟，我们现在知道海洋环流在调节气候方面起着关键作用。海洋环流中最重要的因素之一就是科学家们所说的“子午线翻转环流”(MOC)。这一术语描述了高纬度地区地表水团的冷却和下沉，它们穿过深海的旅程，以及它们最终变暖并在数十年或数百年后返回地表。MOC对气候很重要，因为在海洋中的这一漫长循环中涉及的水团携带着热量、碳和其他重要的物质，如植物营养物质，这些物质通过这种方式分布在地球周围，并被长期锁在深海中。最令科学家困惑的MOC阶段之一，也是气候模拟中最不确定的过程之一，是在南极大陆附近形成的南极底层水(AABW)。AABW是充满MOC最深层的水团，冲刷全球海洋深渊，并将碳和营养物质封存在深海中。然而，尽管AABW在MOC和气候方面处于关键地位，但它仍被许多基本问题所包围。这是因为AABW是在偏远地区形成的，只有很少有海洋船只访问这些地区。因此，我们目前对AABW形成了多少，它是如何从南极海洋输出到世界其他海洋，以及AABW携带了多少碳和营养物质进入全球海洋深渊知之甚少。为了开始回答这些问题，我们计划进行一个实验，在这个实验中，我们将测量韦德尔环流中AABW的生产和出口的速度，以及相关的碳和营养物质的运输。这是一股占据南大西洋和西南印度洋南缘的椭圆形洋流，据信是形成AABW的主要区域。我们将通过(1)测量威德尔环流北缘的温度、盐度、流速、溶解气体、营养物质和碳的分布；以及(2)与美国和德国的两个科学家团队合作，分别在环流东缘和环流西南角进行类似的测量。我们将利用这一史无前例的丰富观测来构建进出韦德尔环流的水团、碳和营养物质的预算。通过这种方式，我们将能够回答一些关键问题，例如‘韦德尔环流中形成了多少AABW？’以及“AABW将多少碳和营养物质锁入全球海洋深渊？”我们对这些问题的回答将作为评估最先进的气候和海洋模型技能的基准，并确定未来的气候变化。

The Earth's climate is changing, as it has done in the past. One of the great challenges faced by scientists today is to understand the causes and consequences of these changes. The way many scientists seek this understanding is by running computer-based climate simulations that mimic the complex interactions between the ocean, atmosphere, ice and living beings that are thought to be responsible for driving climate change. It is partly thanks to these simulations that we now know that ocean circulation plays a key role in modulating climate. One of the most important elements of ocean circulation is what scientists know as the 'meridional overturning circulation' (MOC). This term describes the cooling and resulting sinking of surface water masses in high-latitude regions, their journey through the deep ocean and their eventual warming and return to the surface, after many decades or centuries. The MOC is important to climate because the water masses involved in this long circuit through the ocean carry with them heat, carbon and other significant subtances such as plant nutrients, which in this way are distributed around the planet and locked away in the deep ocean for long periods of time. One of the stages of the MOC that puzzles scientists the most, and one of the most uncertain processes in climate simulations, is the formation near the Antarctic continent of Antarctic Bottom Water (AABW). AABW is the water mass that fills the deepest layers of the MOC, flushing the global ocean abyss and sequestering carbon and nutrients in the deep ocean. Yet in spite of its key place in the MOC and climate, AABW is surrounded by many basic questions. This is because AABW is formed in remote regions that are only rarely visited by oceanographic ships. As a result, we currently know little about how much AABW is formed, how it is exported from the Antarctic seas to the rest of the world ocean, and what quantity of carbon and nutrients is carried by AABW into the global ocean abyss. In order to begin answering these questions, we plan to conduct an experiment in which we will measure the rate of AABW production and export, and the associated transports of carbon and nutrients, in the Weddell gyre. This is an oval-shaped current that occupies the southern rim of the South Atlantic and Southwest Indian oceans, and is believed to be the main region in which AABW is formed. We will do this by (1) measuring the distributions of temperature, salinity, current velocity, dissolved gases, nutrients and carbon along the northern rim of the Weddell gyre; and (2) teaming up with two groups of American and German scientists that will make similar measurements along the eastern rim of the gyre and across the gyre's southwestern corner, respectively. We will use this unprecedented richness of observations to construct a budget of the water masses, carbon and nutrients entering and leaving the Weddell gyre. In this way, we will be able to answer key questions such as 'How much AABW is formed in the Weddell gyre?' and 'What quantity of carbon and nutrients is locked away by this AABW into the global ocean abyss?'. Our answers to these questions will serve as a benchmark to evaluate the skill of state-of-the-art climate and ocean models, and to identify future climate change.