Komt doordat de PARA een heel andere manier van rekenen heeft.
Huidige model:
The GFS model is a spectral model with an approximate horizontal resolution of 13 km for the first 10 days and 27 km from 240 to 384 hours (16 days). In the vertical, the model is divided into 64 layers and temporally, it produces forecast output every hour for the first 120 hours,[1] three hourly through day 10 and 12 hourly through day 16. The output from the GFS is also used to produce model output statistics.
De paralelle run:
In 2019, as a result of the recent tenfold increase in computing power, an upgrade to the GFS model is planned that will increase its horizontal resolution to 9 km and 128 layers out to 16 days, compared to the current run of 13 km and 64 layers out to 10 days. [7]
As of the 12z run on 19 July 2017, the GFS model has been upgraded. Unlike the recently upgradedECMWF, the new GFS behaves a bit differently in the tropics and in other regions compared to the previous version[8]. This version accounts more accurately for variables such as theMadden–Julian oscillationand theSaharan Air Layer.
Long-term plans are for the GFS to receive a new core with dynamic scaling that uses thefinite volume method. The resulting model, being developed under the name FV3, will retain the GFS moniker.[9]The proposal comes after eight years of testing a potential replacement model, the flow-following, finite-volume icosahedral model; the FIM proved to be slower and not appreciably more accurate than the GFS. Initial testing of the FV3 showed promise, outperforming theIntegrated Forecast Systemin terms of hurricane tracks during the 2017 hurricane season (the IFS had been the most accurate operational model in predicting the paths).
De vraag is nu nog waar de ensembles gebruik van gaan maken, of dat de verstoorde situaties zijn gebaseerd op de (nu) para run, of door blijven werken met de huidige oper runs methodiek is vooralsnog de grote vraag.