DMI operates a regional 3D ocean model BSHcmod for the North Sea - Baltic, in order to provide information about the physical state of the Danish and nearby waters in the near future. The Figure to the right shows the model domain for the 3D grid. The parameter shown is the water depth.

The BSHcmod code was developed in the early 1990'ies at Bundesamt für Seeschifffahrt und Hydrographie (BSH) in Hamburg, Germany. It has undergone extensive revision in the DMI implementation. Basically the same code is used in the Baltic HIROMB co-operation, where the Danish institute Danish Maritime Safety Administration participates.

Three types of input is applied: surface fields, point sources, and open boundary conditions. Heat flux through the sea bed is parameterized. BSHcmod is forced by DMI's numerical weather prediction model DMI-HIRLAM. The following parameters are used:

• 10 metre wind speed and direction
• mean sea level atmospheric pressure
• surface (2 metre) air temperature
• surface air (2 metre) humidity
• cloud cover

BSHcmod calculates Surface energy fluxes (mechanical, radiative, thermodynamic) using bulk parameterisation formulae.

Point source data are

• freshwater fluxes from 79 rivers
  • in real-time (German rivers only)
  • obtained from a swedish hydrological model
  • annual climatology
• nutrient from the same rivers (optional)

Open boundary data are:

• tidal sea surface elevation
• monthly climatological hydrography

BSHcmod optionally assimilates one or more types of observered or modelled data:

• sea surface temperature from satellite
• vertical profiles of hydrography
• daily open boundary hydrography data

This facility has not been put in operational use as of yet.

BSHcmod runs every 6 hours, i.e. 4x/day. A run produces a 5 day forecast of the 3-dimensionel state of the ocean.

BSHcmod calculates

• sea level
• water temperature
• salinity
• ocean currents
• ice thickness and concentration

at 15 min.intervals. Temperature, salt and current is calculated for the entire water column, top to bottom, at ~ 50 fixed depth levels. Sea level at selected, coastal points is calculated in 10 minute time resolution.

Output parameter table.

The DMI-BSHcmod model set-up consists of 5 model domains:

• NOAMOD - 2-dimensional mesocale model, that calculates sea level as a function of wind speed and air pressure. Generates boundary data (external surge) for the regional 3-dimensionan model
• North Sea - Baltic Sea - 3-dimensional regional model with subdomains
• Transition Area - high resolution model of the waters south of Skagen and west of Bornholm
• Wadden Sea - high resolution model of the Germasn Bight
• Limfjord - high resolution fjord (appended) model (lacks run-off data)

Model	NOAMOD	BSHcmod North Sea - Baltic Sea	BSHcmod Transition Area	BSHcmod Wadden Sea	BSHcmod Limfjord
Spatial resolution	6' lat 10' lon (6 n.m.)	3' lat 5' lon (3 n.m.)	30" lat 50" lon (0.5 n.m.)	1' lat 1'24" lon (1 n.m.)	12" lat 20" lon (0.2 n.m.)
Vertical layers	1	50	52	24	9
Max. top layers thickness	900m	8m	2m	8m	2m
Time step: Barotropic Baroclinic: Ice	15s - -	30s 90s 900s	15s 90s 900s	30s 90s 900s	10s 20s 900s
Atm. forcing	Hirlam T15	Hirlam S03	Hirlam S03	Hirlam S03	Hirlam S03
Area: longitude	21W-13E	4W-30E	9E-15E	6E-10E	8E-10E
Area: latitude	48N-66N	Baltic Sea: 48N-66N North Sea: 48N-59N	53N-57½N	53N-56N	57N-58N
Open boundaries	Radiation condition	Surge contribution from NOAMOD tidal wave (17 constituents) monthly climatology fields for T and S via a sponge layer	nested in regional model	nested in regional model	boundary data from regional and transition area model