Ocean mixing and internal waves

在过去的几十年里，海洋学家创建了海洋的数值模型，类似于天气模型。随着计算能力的提高，天气模型也得到了改进，这使得模拟观测到的海洋现象的更大比例成为可能。例如，最初的海洋模型过于粗糙，无法解决大约10公里尺度的海洋漩涡，但现在可以做到这一点，至少可以进行短期预测。不幸的是，有些重要的海洋现象太小了，任何可以想象的计算机都无法处理。一个恰当的例子是海洋混合，它发生在厘米尺度上，远远低于今天模型的10公里限制。海洋测量表明，这种混合以复杂的模式发生，而用模式进行的敏感性测试表明，这些模式的微小变化会造成海洋整体状态的巨大变化。这让海洋学家陷入了困境。唯一的解决方案似乎是参数化混合，即仅使用模型可以直接处理的大尺度属性来近似其影响。我的工作集中在创建各种海洋混合现象的参数化。未来几年的重点将是沿海水域高频内波引起的混合。在NSERC和CFCAS的资助下，我的小组收集了一组特别详细的观测结果。希望是将此与小规模数值模拟一起使用，以开发这种混合模式的更可靠的参数化。

Over the past several decades, Oceanographers have created numerical models of the ocean, akin to weather models. As with weather models, improvements have come along as computing power has increased, making it possible to simulate a wider fraction of the observed ocean phenomena. For example, the first ocean models were too coarse to resolve the approximately ten-kilometre scale ocean eddies, but it is now becoming possible to do this, at least for short-term predictions. Unfortunately, there are important ocean phenomena that are too small to be handled by any imaginable computer. A case in point is ocean mixing, which occurs on centimetre scales, far below the 10-kilometre limit of today's models. Ocean measurements reveal that this mixing occurs in complicated patterns, and sensitivity tests with models indicate that small variations in those patterns create large changes in the overall state of the ocean. That leaves Oceanographers in a bind. The only solution seems to be to parameterize the mixing, i.e. to approximate its affects using only the large-scale properties that the models can handle directly. My work centres on creating such parameterizations of various ocean mixing phenomena. The focus over the next several years will be mixing caused by high-frequency internal waves in coastal waters. Funded by NSERC and CFCAS, my group has amassed a particularly detailed set of observations of the phenomenon. The hope is to use this along with small-scale numerical simulations to develop more reliable parameterizations of this mode of mixing.