Some effects of the Atlantic circulation and of river discharges on the residual circulation of the North Sea

In a previous paper the simulation of the tidal and wind generated mean residual circulation in the North Sea was studied, with special references to pollution problems. In that paper, the influence of the Atlantic circulation on the North Sea has been neglected. Referring to the above mentioned paper, in this study the net inflow via the Dover Strait, Kattegat and rivers is simulated in the model. The model runs were repeated, yielding a significant improvement in comparison with observed data. © 1979 Deutsches Hydrographisches Institut

Geochemical cycles in an ocean general circulation model. Preindustrial tracer distributions

A state-of-the-art report is given of the Hamburg model of the oceanic carbon cycle. The model advects geochemical tracers important to the carbon cycle by the currents of a general circulation model. The geochemical cycling is driven by a Michaelis - Menten type production kinetics. The model is an extension of the Bacastow and Maier-Reimer (1990) model. It is based-on-a more realistic current field and includes a mechanism of lysocline - sediment interaction. Principal variables are SIGMACO2, alkalinity. phosphate, oxygen, and silicate. The carbon variables are defined for C-12, C-13, and C-14 separately. In addition to these carbon isotopes, 39A and deltaO-18 of dissolved oxygen are predicted. The model predicts realistic global patterns of tracer distribution. In the equatorial eastern Pacific, however, the structures are exaggerated due to a strong upwelling which is a common feature of coarse resolution models of the general circulation of the ocean

An explicit numerical model to simulate upwelling events

A three-dimensional numerical model for upwelling has been developed and tested under various boundary conditions. Gridsize and bottom topography are variable; the driving force is windstress. A version o f the model was applied to data from the “ Upwelling 75” experim ent. Certain wind-induced events observed in the data are reproduced reasonably well, although wind input is done by m eans of linear approx­ imation. Typical upwelling conditions can be achieved and the influence of bottom topography can be shown

Climatology of the HOPE-G Global Ocean - Sea Ice General Circulation Model

TM2 is a three-dimensional atmospheric transport model which solves the continuity equation for an arbitrary number of atmospheric tracers on an Eulerian grid spanning the entire globe. It is driven by stored meteorological fields from analyses of a weather forecast model or from output of an atmospheric general circulation model. Tracer advection is calculated using the “slopes scheme” of Russell and Lerner [1981]. Vertical transport due to convective clouds is computed using a simplified version of the cloud mass flux scheme of Tiedke [1989]. Turbulent vertical transport is calculated by stability dependent vertical diffusion according to the scheme by Louis [1979]

What controls the oceanic dimethylsulfide (DMS) cycle ? A modeling approach

We implemented a process-based DMS module into the global carbon cycle ocean model (HAMOCC5) which includes a simple module for plankton dynamics and investigated the regional and seasonal variations of the marine sulfur cycle. The turnover rates within the DMS cycle are only poorly known. Therefore we developed, on the basis of a global DMS data set, an optimization routine for the free parameters controlling DMS production and removal. The resulting seasonal and regional distributions of DMS concentration are fully consistent with the underlying hydrodynamical and biogeochemical processes. We investigated a series of DMS model approaches with various complexities. The distinction between different DMS producing phytoplankton species and the consideration of the regionally and seasonally varying bacterial activity on converting dDMSP to DMS and on DMS consumption appears to have a crucial effect on the quality of the results in the given model conception

The Hamburg Ocean Primitive Equation Model HOPE

HOPE is a primitive-equation model of the global ocean circulation, but may also be used for regional studies. Prognostic variables are the three-dimensional horizontal velocity fields, the sea-surface elevation, and the thermohaline variables. The equa- tions are discretized on prescribed horizontal surfaces using Arakawa-E-type grids. Two time levels are used for the integration. A Hibler-type dynamic sea-ice model allows a prognostic calculation of sea-ice thick- ness, compactness, and velocities. The thermodynamic growth of sea ice is calculated with heat balance equations using simple bulk formulae. A snow layer is included. HOPE is in particular useful for altimetry data assimilation purposes because of the prognostic calculation of the sea-surface elevation