The SubX models¶
PyCPT currently allows the following SubX models to be used:
NCEP CFSv2: initialized every 6 hours
EMC GEFSv12: initialized every Wednesday
ESRL FIM: initialized every Wednesday
ECCC GEM (GEPS6): initialized every Thursday in real time
Important Notes¶
Except for ECCC (Environment Canada), the hindcasts were made every Wednesday during the 1999–2016 hindcast period using a fixed version of the forecast model.
ECCC uses a different approach in which a new set of hindcasts is made every time that a that a forecast is made (i.e. every Thursday in real time). This “on-the-fly” approach allows ECCC to update their forecast model whenever they want. ECMWF also uses an on-the-fly approach.
When ECCC makes a forecast every Thursday in real time, they run a set of 20 hindcasts initialized on the same calendar date of each year 1998–2017. But note that these hindcast starts are generally not on Thursdays of the hindcast!
The CFSv2 forecasts are initialized every 6 hours with 4 members (1 member for the hindcasts). A lagged ensemble is used to augment the ensemble size, by including the initializations over 1 or more days. This involves a trade off between ensemble size and increasing lead time. PyCPT uses a 3-day lagged ensemble, which yields 12 ensemble members (3 x 4) for the hindcasts and 48 for the forecasts (3 x 16).