If you are using the explicit overland flow solver, the time step depends on the location in the model with the critical Courant criteria. The grid series output allows you to save the Courant criteria, so that you can see where the critical locations are. However, the grid series output is an average Courant number over the storing time step, where there can be hundreds of OL time steps in a storing time step. If you are experiencing very short time steps due to short duration rainfall events, for example, the critical information can be difficult to distill from the dfs2 grid series output.
To make it easier to find the critical locations, an extra parameter option was added that writes out the critical locations at every time step, if the time step is reduced below a user-defined fraction of the storing time step.
|
Parameter Name |
Type |
Value |
|---|---|---|
|
adaptive OL time step info threshold fraction |
Float |
between 0.0 and 1.0 Default = 0.01 |
The default value is 0.01. This means that if the reduced time step is less than 0.1 times the Max OL time step, then a message will be printed in the _WM.log file. Such as:
Adaptive time step info from Explictit OL solver:
OL step no: 59: ... Final time step = 1.8108 seconds
with the following four reasons:
Critical: OL Wave Courant number. Cell (8,21)...
Critical: Net outflow from OL cell to River. Cell (8,21) ...
Critical: Net OL outflow from cell. Cell: (17,19) ...
Critical: Net outflow from River to OL. River link between ...
If you experience frequent severe reductions in the OL time step when using the explicit OL solver, then this threshold can cause very large log files to be created. If you are not interested in this information, then you can reduce this threshold to reduce the frequency of the output.