MESoscale Ocean eddies and Climate Predictions (MESO-CLIP)

中尺度海洋漩涡（MOEs）是在世界海洋中普遍存在的水漩涡（通常直径几百公里）。moe相当于海洋中的大气天气系统。与天气系统类似，moe不能提前很长时间预测。在海洋的计算机模型中，只有当模型能够分辨的空间尺度足够小时，moe才能发展。通常，一个模式需要能够分辨大约30公里（中纬度地区）的尺度，才能开始产生moe。一个海洋模型被认为是允许涡流的。要想很好地表示moe，需要至少10公里的空间尺度。具有这种分辨率的海洋模型通常被称为涡流分辨率。直到最近，用于气候预测的气候模式中的网格分辨率太粗（100公里以上），无法模拟moe。这种情况现在正在改变，正在开发的最新一代气候模型使用的海洋成分允许涡流（很快就会解决涡流）。在高分辨率模式中moe发生的时间和地点取决于初始条件（模式模拟开始时的温度、盐度和速度）。即使初始条件的微小变化最终也会导致不同的MOE场。这类似于天气模式，当初始条件在预报开始时受到干扰时，通常会在几天内采用不同的模式。moe如何反馈气候变率和可预测性在很大程度上仍然未知。然而，最近的一些研究表明，moe可能在年际到年代际的时间尺度上影响海洋和大气的变化。目前正在开发的尖端气候模式使用允许涡流（如英国的HadGEM3-H）和涡流分解（如美国的CM2.6）海洋，因此有必要更好地了解moe如何影响基于此类模式的预测。MESO-CLIP的主要目标将是确定初始条件（温度、盐度、速度）如何在允许涡流/解析海洋模型中受到干扰，以评估预报的不确定性。我们将使用分层的数值模式：(i)以水平网格分辨率为1/4度（赤道25公里）和1/12度（赤道9公里）运行的非耦合全球海洋模式，（ii）英国气象局目前正在开发的最新的耦合海洋-大气模式（HadGEM3-H），它使用1/4度的海洋成分，以及（iii）涡旋分辨率（1/20度）的理想耦合海洋-大气模式。有了这组模式，我们将能够解决海洋moe的存在如何影响海洋和大气的可预测性和可变性，以及耦合过程（海洋和大气之间的相互作用）可能有多重要。因此，MESO-CLIP将提供有关当前和未来用于气候预测的高分辨率耦合模式预测不确定性的宝贵知识。

Mesoscale ocean eddies (MOEs) are swirls of water (typically a few hundred km in diameter) that are ubiquitous in the World Ocean. MOEs are the oceanic equivalent of weather systems in the atmosphere. In analogy to weather systems MOEs cannot be predicted a long time in advance. In computer models of the ocean MOEs can only develop if the spatial scale that the model can resolve is small enough. Typically a model needs to be able to resolve scales of about 30km (at mid-latitudes) to start generating MOEs. An ocean model is then said to be eddy-permitting. For a good representation of MOEs the resolved spatial scales need to be at least 10 km. Ocean models with that resolution are often referred to as eddy-resolving. Until recently, the grid resolution in climate models used for climate prediction was too coarse (100 km and more) for MOEs to be simulated. This is now changing and the latest generation of climate models under development use ocean components that are eddy-permitting (and soon eddy-resolving). When and where MOEs occur in high resolution models depends on initial conditions (the temperature, salinity and velocities at the beginning of the model simulation). Even small changes in initial conditions will eventually lead to different MOE fields. This is analogous to weather patterns typically adopting different patterns in a matter of days when the initial conditions are perturbed at the beginning of a forecast. How MOEs feed back on climate variability and predictability is still largely unknown. However, some recent studies suggest that MOEs could affect ocean and atmosphere variability on interannual to decadal timescales. Cutting edge climate models currently under development use eddy-permitting (e.g. HadGEM3-H in the UK) and eddy-resolving (e.g. CM2.6 in the US) oceans and therefore there is a need to get a better understanding of how MOEs affect forecasts based on such models. The main goal of MESO-CLIP will be to determine how initial conditions (temperatures, salinities, velocities) have to be perturbed in eddy-permitting/resolving ocean models to assess the uncertainty in forecasts. We will use a hierarchy of numerical models: (i) an uncoupled global ocean model run at horizontal grid resolutions of 1/4degree (25km at Equator) and 1/12degree (9 km at Equator), (ii) the latest coupled ocean-atmosphere model currently under development at the UK MetOffice (HadGEM3-H) which uses a 1/4degree ocean component, and (iii) an eddy-resolving (1/20degree) resolution idealised coupled ocean-atmosphere model. With this set of models we will be able to address how the presence of MOEs in the ocean affect the predictability and variability of ocean and atmosphere and how important coupled processes (interactions between the ocean and the atmosphere) are likely to be. MESO-CLIP will therefore provide valuable knowledge about forecast uncertainties in present and future high resolution coupled models that will be used for climate predictions.