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10/17/2015 6:02 am  #1


GFS Ensemble Modeling System (GEFS)

A recent article in Scuttlebutt concerning improvements to the GFS forecasting system notes: 
"This month, NWS is set to deploy a significant improvement in the GFS Ensemble Modeling System (GEFS,,,,,
A powerful tool with particular application to offshore racing, the GEFS differs from the GFS in that it is a collection of over 20 models all based on the GFS, but each with slightly different initial conditions. The idea behind the GEFS is to recognize the fact that we cannot perfectly describe the initial state of the atmosphere. In order to model the future, we must make some assumptions as to what is happening between observation stations or locations where we do know the initial conditions in detail.  Invariably, as the forecast projects forward in time, error is induced in the forecast due to the assumptions made at the beginning. We see this in the GEFS as the forecasts of the individual members diverge from each other as time projects forward in the forecast.  In application to Ocean Racing, the GEFS allows for a more useful Optimum Route Analysis when we can see the sensitivity of the forecast to the initial conditions.  In cases where the solutions between the GEFS model members are quite similar, we can have higher confidence in the forecast and routing solutions. Alternatively, when the solutions begin to diverge between the members (and they always do over time), our confidence in the forecast and routing projections diminishes.  This trait of relating the forecasts to confidence or reliability is extremely valuable when determining what optimum route to take or race strategy to employ"

Question - Expedition has both the US and Canadian GEFS under the NOAA tab.  Will the software be able to show the senstivity of these forecast models in some manner?

Thanks
Dave Christensen
Houston Texas
 

 

10/17/2015 6:14 pm  #2


Re: GFS Ensemble Modeling System (GEFS)

There is an option to produce an optimised route for each ensemble model. This can be used for different model sources (Eg GFS, GEM, Arpege, EC etc.

You can also draw all​ models on the chart at the same time.

 

11/06/2015 3:58 am  #3


Re: GFS Ensemble Modeling System (GEFS)

Once an  optimized route is produced can you capture it as a series of waypoints?

 

11/07/2015 7:02 pm  #4


Re: GFS Ensemble Modeling System (GEFS)

Yes ...

 

11/08/2015 10:09 am  #5


Re: GFS Ensemble Modeling System (GEFS)

Ah...how?

 

11/08/2015 11:18 am  #6


Re: GFS Ensemble Modeling System (GEFS)

See the route optimisation settings page. Also described in the help for that page.

 

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