<p>Cool, didn't realize that the GFS was on Github.</p>
<p><a href="https://github.com/NOAA-EMC/global-workflow/wiki/Run-Global-Workflow#view-experiment-output" rel="nofollow noreferrer">Looking on down the wiki</a>, it seems like the &quot;free-forecast&quot; is associated with the deterministic model, while the &quot;cycled&quot; is associated with the Ensemble Kalman Filter. That is, the free-forecast is not constrained by data assimilation algorithms- it can just start from a restart file and go. A cycled run, however, needs multiple runs, as well as data.</p>
<p>This is all speculation based on naming conventions. If you really want an answer, perhaps <a href="https://github.com/NOAA-EMC/global-workflow/wiki" rel="nofollow noreferrer">asking the code developer</a>?</p>

CC BY-SA 4.0
2020-10-30T20:39:38.703Z
2020-10-30T20:39:38.703Z
BarocliniCplusplus
<p>What is the difference between a free forecast and a cycled model run?  <a href="https://github.com/NOAA-EMC/global-workflow/wiki/Run-Global-Workflow#run-setup-scripts-to-generate-experiment" rel="nofollow noreferrer">This GFS wiki</a> mentions both, but does not define them.</p>

<models><atmosphere-modelling>
Free forecast vs cycled model runs
DavidH
# Free forecast vs cycled model runs

(Asked by: username_0 on 2020-10-30)

What is the difference between a free forecast and a cycled model run? [This GFS wiki](https://github.com/NOAA-EMC/global-workflow/wiki/Run-Global-Workflow#run-setup-scripts-to-generate-experiment) mentions both, but does not define them.

**Tags:** models, atmosphere-modelling


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## 1 answers

### Answer by username_1 on 2020-10-30. Score: 2 | Accepted answer

Cool, didn't realize that the GFS was on Github.

[Looking on down the wiki](https://github.com/NOAA-EMC/global-workflow/wiki/Run-Global-Workflow#view-experiment-output), it seems like the "free-forecast" is associated with the deterministic model, while the "cycled" is associated with the Ensemble Kalman Filter. That is, the free-forecast is not constrained by data assimilation algorithms- it can just start from a restart file and go. A cycled run, however, needs multiple runs, as well as data.

This is all speculation based on naming conventions. If you really want an answer, perhaps [asking the code developer](https://github.com/NOAA-EMC/global-workflow/wiki)?


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