Processing (Simulation)

The model itself is a command line program without any graphical user interface. Thus, it can run on different computer systems (Windows, Linux, Unix).

During initialization of the model, all input data is opened. For climate data and hydrological data the specified start date is lokated and the data is read into internal chache structures to minimize hard disc access and to maximize performance. Spatially distributed data sets (grids) are completely read in, examined for missing values, which are automatically (up to a certain limit) replaced with the mean values of adjacent cells (see also: automatic data completion). These initializing manipulations are logged in a log file.

During model execution a large number of large result files are generated, which are buffered in memory as well (thus minimizing hard disk access and maximizing perfomance but requiring sufficient RAM in the computer). Spacial data sets (grids) can be written per interval or per n intervals, per day, month or year, each as total sum or average values. Minimum and maximum value or aggregation for the vegetation period only (individual per cell!) are also possible output options.

Time series outputs can be generated for subbasins and the total basin per time step or aggregated over a pre-defined range of intervals as sums or averages. During the execution of the model the space loop is nested into the time loop. This means, that the entire model structure (i.e. all the modules like interpolation, evapotranspiration, snow model, soil model, runoff routing etc. is executed for all grid cells for one time step before a new time step starts; within a module, the entire grid is processes cell by cell before moving to the next module).