User Manual | Solver settings | Wind variations

The wind GRIB files used by the solver may contain a few different wind fields:

  • 10m wind speed and direction.
  • surface wind gust.
  • NBM Oceanic probability winds.
  • GEFS / CMC ensemble mean (average) and control winds.
  • full GEFS ensemble winds.

One of the most difficult concepts to reason about, with regard to weather routing, is how to deal with forecast uncertainty. The weather routes that are generated are only as accurate as the weather forecasts we have access to. All long term weather forecast models have their forecast uncertainty grow and grow as you move later into the forecast.

There is a discussion of uncertainty in the Introduction / Uncertainty? area.

This setting is used to control the number of generated solutions when there is more than one wind field present in a file. This can be used to observe the differences in routes when built using various wind fields.

When the option is on.

If this setting is enabled, then the solver will generate solutions for each wind field it finds in the wind file.

For wind gust, the solver will use 10m wind direction and wind gust speeds. The wind gust solution is not meant to be a realistic possibility for a path you could sail. Gusts come and go, we do not experience steady wind speeds for the wind gust parameter the forecast models output. However, viewing a wind gust solution, along with a normal 10m wind solution, may give you some sense of the uncertainty in the weather.

When working with the NBM Oceanic winds, there is a single wind direction field provided, with different probability wind speeds. Each of the combinaions of wind speed and direction are solved when this option is enabled.

Ensemble files may contain many different wind fields (up to 22.) When this option is turned on, all of the wind fields present in the file are used.

When the option is off.

When this option is off, but there are multiple wind fields available in the file:

  • wind gust is ignored.
  • only the NBM Oceanic mean wind, 50% probability, is used.
  • only the ensemble mean is used.