Some GOTM Physics SOPRAN GOTM School Warnemünde: Hans Burchard Baltic Sea Research Institute Warnemünde, Germany

1D equations which are explicitly implemented into GOTM: momentum equations (x- and y-directions) potential temperature salinity turbulence equations (zero-, one-, or two-equation model) Processes included: Earth rotation (depending on latitude) external pressure gradients internal pressure gradients vertical advection equation of state (fully non-linear)

Options for these processes: External pressure gradient: prescription of surface slopes prescription of depth-mean velocity presciption of velocity time series in one point GOTM will then calculate the surface slope, which goes into the momentum equations as external pressure gradient Internal pressure gradient:prescribe horizontal gradients of T & S GOTM will then calculate the horizontal density gradient, which goes into the momentum equations as internal pressure gradient Advection of T & S may be calculated from the gradients and the velocity profile (restoring avoids run-away stratification). Variable water depthThis may be relevant when the surface elevation amplitude is high compared to mean water depth

u<0u>0   /  x < 0 Example for internal pressure gradient & advection of S tidal phase

Nudging (same as restoring): For u, v, T and S, GOTM users may chose simulations to be nudged to observations at a certain time constant  : For large , nudging is small, for small  nudging is strong, for infinite , there is no nudging.

Vertical advection: If effects of vertical advection (e.g. internal tides) should be reproduced, then a vertical velocity profile of triangular shape (zero at surface and bottom) may be prescribed. This vertical advection will affect temperature and salinity profiles.

Example of vertical advection: Observations and simulations in the Northern North Sea.

Observations of u, v, T, S, and  may be included into GOTM: The observations of u, v, T, S may be used for initial conditions, nudging, analysis. The observations of  may be used for analysis only.

For the air-sea fluxes (see modelling talk), the Kondo 1975 bulk formulae are included, the more advanced Fairall et al. (1996) formulae are about to be implemented. For the short-wave radiation Jerlov classes may be prescribed or parameters given user-defined. Spectral models will be included within the SOPRAN project. For the turbulence closure models (see modelling talk), many formulations are included, such that GOTM is a state-of-the-art library for turbulence models. So far, counter-gradient fluxes are not included, but this may change during the next years. So far for the GOTM physics.