# Introduction to the calculation domain

This module handles all tasks related to the definition of the computational domain - except reading in variables from file. The required information depends on the and also on the complexity of the model simulation to be done.
The mandatory varible read from the file containing the bathymetry and coordinate information (presently only NetCDF is supported) is guiding subsequent tasks. can take the following values:

1:
equi-distant plane grid - , are constant - but not necessarily equal
2:
equi-distant spherical grid - , are constant - and again not necessarily equal
3:
curvilinear grid in the plane - , are both functions of (i,j). The grid must be orthogonal

For all values of the bathymetry given on the T-points (see the GETM manual for definition) must be given.

Based on the value of the following additional variables are required:

1:
proper monotone coordinate informtion in the xy-plane with equidistant spacing. The name of the coordinate variables are and .
2:
proper monotone coordinate informtion on the sphere with equidistant spacing in longitude and latitude. The names of the coordinate variables are and .
3:
position in the plane of the grid-vertices. These are called X-points in GETM. The names of these two variables are and .

In addition to the above required grid information the following information is necessary for specific model configurations:

A:
and
If is false information about the latitude of U- and V-points are required for calculating the Coriolis term correctly. For and are calculated based on an additional field i.e. the latitude of the T-points. For i.e. the latitude of the X-points will have to be provided in order to calculate and .
B:
, and
The longitude, latitude positions of the T-points are required when using forcing from a NWP-model. and are used to do spatial interpolation from the meteo-grid to the GETM model and is the rotation of the local grid from true north.

In addition to the information above a few files are optionally read in . Information about open boundaries, modifications to the bathymetry and the calculation masks are are done via simple ASCII files.

Subsections
kklingbe 2017-10-02