Ocean mixing and internal waves

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.