Author

Topic: Environment Canada Ocean Wave Models

Sean

posted November 11, 2008 06:29 PM
Environment Canada posts Ocean Wave Models on their site at http://www.weatheroffice.gc.ca/model_forecast/wave_e.html Not sure if anyone is familiar with these models, but I am not clear on the 'runs' vs 'forecasts'. For each area listed they have a 00z and a 12z run. Does this mean that the snapshot is taken starting at 0000 GMT and 1200 GMT on a particular day? If so, which one should you choose?
From: Toronto, Ontario


David Burch

posted November 11, 2008 10:24 PM
this is a very good question, because the way they do these is exactly the way they (everyone) do the atmospheric model calculations that give us the GRIB forecasts.
The run time is the UTC of the computation. That is, a run time of 0600 means the input data used to seed the model were all valid at 06z. then this model makes what is called a 00 06 12 18 forecast. the 00 is just the valid time, so a 00 forecast is valid for 06z in this example. the 06h forecast is 6h later of 12z, etc.
In all of the model computations (for atmosphere or ocean) the "00 forecast" is the valid time of the computation. These by the way will typically be some 4 to 6h later than the actual UTC.
These matters are also discussed in the text book. Search the ebook under "valid time" to get a list of discussions.
so to summarize, the forecast times are not real times, but intervals past the computation time called run time.
From: Starpath, Seattle, WA


