Impact of Typhoons on the Western Pacific Ocean DRI: Numerical Modeling of Ocean Mixed Layer Turbulence and Entrainment at High Winds
Abstract
This ongoing collaborative effort aims at measuring and modeling the response of the upper ocean to strong typhoons both in simple, open ocean conditions and in the more complex conditions caused by ocean eddies and preconditioning by prior storms. The measurement and modeling activities include a focus on the impact of surface waves; air-sea fluxes; and the temperature, salinity, and velocity structure of the upper ocean. The goals of this effort are to understand key upper ocean processes, test upper ocean models, develop and test new parameterizations of upper ocean physics, and study the feedback from the ocean to typhoon intensity. We used field observations to force Large Eddy Simulations (LES) and upper ocean turbulence models in equivalent numerical cases. We also used model-data comparison to test the theoretical basis of mixed layer turbulence scalings and parameterizations. The strategy is to test our physical theories and parameterizations of mixed layer dynamics against data by incorporating them realistically in turbulence-resolving LES models with embedded virtual measurements. Verification of the underlying theories can then be achieved through direct model-data comparison, using observations of ocean waves and turbulence under a wide range of oceanic conditions. This should lead to improved parameterizations of upper ocean turbulence. The strong and isolated wind forcing in tropical cyclones provides an ideal environment for testing theories and parameterizations of the role of surface waves in the ocean mixed layer. We have identified a closure model based primarily on the Craik-Leibovitch vortex force as likely to predict upper ocean turbulence, including under the winds of tropical cyclones. Work has therefore continued on the development of a second moment closure model that more correctly represents the effect of these vortex force terms, due to the interaction of surface wave Stokes drift and Eulerian current shear within the mixed layer.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 30, 2011
- Accession Number
- ADA557092
Entities
People
- Ramsey R. Harcourt
Organizations
- University of Washington