05.05.2014: FB1-Seminar

 11:00 h, Hörsaal, Düsternbrooker Weg 20

Abstract

The effect of Langmuir circulation (LC) on vertical mixing is parameterized in the ocean mixed layer (OML) model, based on the analysis of LES results using PALM (Noh et al. 2011). Parameterization of LC effects is carried out in terms of the modifications of the mixing length scale as well as the inclusion of the contribution from the Stokes force in momentum and TKE equations, in the OML model developed by Noh and Kim (1999) and Noh et al. (2002). In this way vertical mixing becomes stronger in the presence of LC only for weaker stratification and shallower depths with the larger enhancement for stronger LC, as in the model suggested by Li and Garrett (1997). The performance of the new OML model is examined by the comparison with LES results for the case of the wind-mixed layer deepening. The new OML model is then applied to MRI.COM, the OGCM developed by MRI (Tsujino et al. 2011), and its effect is investigated. The parameterization of LC effects is found to affect mainly the high-latitude ocean, in which stratification is weak. The new OML model helps to rectify the underestimation of the mixed layer depth in the high-latitude ocean, which is a common error in most OGCMs, while avoiding producing a more diffuse thermocline in the tropical ocean.

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