Running a nested Simulation with the WS Eta

Version 3.1 of the SOO/STRC WS Eta includes non-concurrent 1 way nesting capability. What this means is that in order to run a nested (fine mesh) simulation you must first complete a coarse mesh run and process the model output at 1 hour frequency. These data will then provide the initial and boundary condition data for the nested run. One advantage of nesting is that you can get away with a smaller interior domain, and grid spacing than you otherwise could with a single grid. The downside is that you still need to make 2 simulations and it takes additional time to process the coarse mesh for the nested run.

To run a nested simulation you will need to:

1) edit the NEST_<PARAMETER> variables in eta_run.csh to define your nested forecast

2) Set SAVE_FOR_NEST in eta_convert.csh to YES

3) Run the coarse mesh simulation as you would any simulation:

a) run eta_download.csh

b) run eta_run.csh

c) run eta_convert.csh

If you have set SAVE_FOR_NEST to YES then eta_convert.csh will processes the WS ETa model 1-hourly grib files and move them to the $ETA_PREP directory for use in the nested forecasts. No other processing will be done.

4) Run eta_download.csh to processes the coarse mesh grib files now located in $ETA_PREP

% eta_download.csh WSE <CYCLE> <INIT> <FINAL> 01 C <YYMMDD>

5) Run the eta_run.csh script to run the nested simulation. Pass the "N" argument.

% eta_run.csh N

6) Run eta_convert.csh

% eta_convert.csh N

7) Enjoy the model output

Note that if you are using eta_autorun.csh script then all you will have to do is configure your nested run in eta_run.csh and set SAVE_FOR_NEST to YES in eta_convert.csh. Everything else will be taken care of.