Value Of the Rapid array for climate predictions (VALOR)

大西洋子午线翻转环流(AMOC)包括温暖的表层水向北移动和寒冷的深水向南移动。净影响是将~1PW的热量向北输送。这些热量被释放到中高纬度的大气中，在那里它起到了使气候变暖的作用，特别是在北欧。AMOC的未来行为在气候预测中是一个非常重要的问题。政府间气候变化专门委员会(IPCC)提出的预测表明，为了应对温室气体强迫，AMOC可能会放缓，从而减少大西洋向北输送的热量，并导致北欧降温，从而抵消人为变暖的影响。此外，来自古气候记录的证据表明，AMOC可以经历非常快速的过渡，例如在十多年内完全关闭。温室气体水平的增加可能会引发如此迅速的变化，给欧洲和大西洋盆地周围其他地区的社会带来潜在的严重后果。面对这样的风险，显然有必要对AMOC的未来行为做出更好、更定量的预测。这样的预报可以为未来AMOC可能的快速变化提供早期预警。快速阵列是观察AMOC当前状态的测量系统。该阵列成立于2004年，首次提供对AMOC的直接和连续测量，根据快速观察方案，这些测量将保持十年。Valor项目的首要目标是评估这些观测结果对于预测AMOC未来行为及其对气候的影响的价值。该项目将探讨与潜在的AMOC预测系统的设计有关的一系列问题。为了实现其目标，Valor将以各种方式利用快速观察。首先，这些观测值将作为独立数据用于评估当前海洋“分析”的质量(“分析”提供对给定时间海洋状况的定量描述。)接下来，它们将被用来改进分析。最后，他们将被用来为一大套“后播”提供开始条件。后播是对过去某个日期的预测，它只利用在那个日期可以获得的信息。然后，可以将这些预测与实际发生的情况进行比较，以评估预测技能。Valor将进行一系列事后预测实验，以量化快速观测可以在多大程度上提高对AMOC及其对气候影响的预测技能。该项目的一个重要方面是，它涉及直接参与业务气候预报的机构：气象局哈德利中心(Mohc)和欧洲中期天气预报中心。通过从一开始就让这些合作伙伴参与，该项目将受益于他们的经验和专业知识，通过研究取得的科学进步将直接提供给更好的气候预测。

The Atlantic Meridional Overturning Circulation (AMOC) involves a northward movement of warm surface waters balanced by a southward movement of cold deep waters. The net effect is to transport ~1PW of heat northwards. This heat is released to the atmosphere in mid-high latitudes, where it acts to warm the climate, notably in northern Europe. The future behaviour of the AMOC is an issue of major importance in climate prediction. Forecasts presented by the Intergovernmental Panel on Climate Change (IPCC) suggest that, in response to greenhouse gas forcing, the AMOC may slow down, reducing the northward transport of heat by the Atlantic Ocean, and leading to a cooling of northern Europe that could offset anthropogenic warming. Moreover, there is evidence from palaeoclimate records that the AMOC can undergo very rapid transitions such as a total shutdown within little more than a decade. It is possible that increasing levels of greenhouse gases could trigger such a rapid change with potentially serious consequences for societies in Europe and other regions surrounding the Atlantic basin. In the face of such risks, there is an obvious need for better, more quantitative, forecasts of the future behaviour of the AMOC. Such forecasts could provide early warning of possible rapid changes in the AMOC in future The RAPID array is a measurement system for observing the current state of the AMOC. Established in 2004, the array is providing direct and continuous measurements of the AMOC for the first time, and under the RAPID-WATCH programme these measurements will be maintained for a decade. The overarching goal of the VALOR project is to assess the value of these observations for predicting the future behaviour of the AMOC, and its impacts on climate. The project will explore a range of issues concerning the design of a potential AMOC prediction system. To achieve its goals VALOR will exploit the RAPID observations in a variety of ways. First the observations will be used as independent data to assess the quality of current ocean 'analyses' (An 'analysis' provides a quantitative description of the state of the ocean at a given time.). Next, they will be used to improve the analyses. Finally, they will be used to provide the starting conditions for a large set of 'hindcasts'. Hindcasts are predictions made from a date in the past, which only make use of information that would have been available at that date. These predictions can then be compared to what actually happened to assess prediction skill. VALOR will carry out a suite of hindcast experiments to quantify the extent to which the RAPID observations can improve the skill of predictions of the AMOC and its impacts on climate. An important dimension of the project is that it involves agencies who are directly involved in operational climate forecasting: the Met Office Hadley Centre (MOHC) and the European Centre for Medium Range Weather Forecasting. By involving these partners from the start the project will benefit from their experience and expertise, and the scientific advances achieved through the research will feed directly into better climate predictions.