If-less KPP

Alexander Shchepetkin
UCLA

Over the years vertical mixing schemes have been shown to be a major factor which controls success or failure of realistic ocean modeling. The problem is especially challenging because of multiple mixing regimes occurring in oceanic conditions, which makes a model focusing of a particular physical scenario to be unsuccessful, while multi-process schemes involve conceptually complex (and often not well defined) rules of transition between different regimes. The practical constraints impose the requirement that the model must be able to work at relatively coarse resolution, which puts preference to relatively a low-order closure, emphasis on careful design of numerical discretizations to escape the problem of resolution dependency of behavior of the model. This talk presents an integral version of KPP, which is built around a boundary layer algorithm capable of smooth transition between regimes of shear layer instability, Ekman layer and convective boundary layer, and which matches the correct projections in these pure limits. Also discussed are numerical techniques to counte "resolution drift", which prevents successful parameter tunnig, practical verification using results from ROMS Pacific model.