FAQ

This FAQ aims to provide basic explanations about the meaning of some model entries and to clarify scientific jargon. Please take also a look at the already uploaded model entry forms.

Explanations and comments to the model entries
How do the model types differ from each other?	Hydrodynamic: Simulation of water motions Ecosystem: Simulation of ecological processes (incl. water quality, trophic interactions) Subpart: Focus is on a certain part of the system, e.g. trophic level, specific chemical process (e.g. bubble ebullition)
How can I imagine the model structure?
How are the widths of each layer formulated?	Lagrangian structure: Model layers act as ‘control volumes’ and can modify their thickness (flexible grid) Euler structure: Thickness of each model layer is fixed (fixed grid)
What are the types of input variables?	Obligatory: State variables that are crucial to run the model Optional: State variables that can be added to reduce model assumptions
What are these different file formats?	ASCII: Standard code for electronic communcation, easily readable with a text editor .netcdf: Network common data format, written in binary and mostly used in scientific applications .csv: Comma-separated values, plain text, used to easily store tabular data .xls: Spreadsheet data from Microsoft Excel
What are these mathematical frameworks?	ODE: Ordinary differential equations like dx/dt=x PDE: Partial differential equations like the heat equation du/dt – a ( d²u/dx² + d²u/dy² ) = 0
What is the calibration step?	Fitting simulated data to observed data, mostly followed by a validation step in which the model fit is checked for a different simulated time period
What do you mean by shallow and deep?	Not clearly defined; for most applications a lake/reservoir with a mean depth below 10 m could be declared as shallow; whereas often shallow also means that the photic zone reaches to the bottom of the lake
What are the meanings of the trophic criteria?	Oligotrophic: Low concentrations of nutrients and low primary production Mesotrophic Intermediate concentrations of nutrients and moderate primary productivity: Eutrophic: High concentrations of nutrients and high primary productivity causing oxygen depletion
What are internal waves?	Oscillating gravity waves that occur in stratified surface water bodies, similar to seiches	| What are the differences regarding accessibility?	Open-source: Freely available access to source code Open-to-use: No access to source code
What are examples for the processing tools?	Pre-processing: Aggregates automatically input and boundary conditions, e.g. Janet for grid and mesh generation Post-processing: Visualizes model results and computes additional parameters from model results, e.g. GLMr for GLM or LakeAnalyzer