Whats the difference between the GEFS Operational run and the Control run?

[Jonathan Lang]

Just a quick question that has had me lost since joining the site.

[Paul]

The operational run is the mean GFS run, the control run is the GFS ensemble run which is started without any adjustments made to it's initial data.

[Winter1981]

Hi

I am also trying to understand the difference between the operational and control run.

Paul - you say above that the operational run is the mean GFS run. However, if I look at the graphs there is separate line for the GFS mean and it is different to the operational. Confused!

Thanks for your help

[Gibli]

Operational run = high resolution model, no change to initial conditions

Control run = as operational model but a lower resolution model (i.e. less horizontal and vertical grid points)

Ensemble runs = the lower resolution model (same as control run) but with small changes to initial condtions

[Radiating Dendrite]

Is the control not a bit pointless then?

I wonder if anyone really knows as I have heard so many conflicting reports of what each is etc.

So long as it shows cold that is the main thing in winter and warmth in summer!

[SomeLikeItHot]

No the control is a "control" when it differs from the op then you know the resolution is having an effect on the outcome.

Helps identify when the Ensemble spread is due to initial condition variations as opposed to resolution issues.

Eg given the below graph

We get a similar result until the 8th of April. Then something quite different. Doesn't invalidate the rest of the ensembles, but does make you aware that the differences could be due increasingly just to resolution issues.

Also I note that a point difference (T850 at one location) may only represent a small difference to the overall evolution just magnified at that one point, you would need to look at the overall synoptics.