Waarschijnlijk het meest gehanteerde weermodel voor de middellange termijn ter wereld, het GFS (Global Forecast System), wordt vanaf komende zomer aangepast en dat levert hoogst waarschijnlijk een nauwkeurigere uitvoer op.
Het model wordt zo frequent gebruikt, omdat de uitvoerdata vrij toegankelijk voor iedereen is (dit in tegenstelling tot data van het ECMWF) en het voor de hele wereld gedraaid wordt. Van wikipedia:
"The Global Forecast System (GFS) is a global numerical weather prediction computer model run by NOAA. This mathematical model is run four times a day and produces forecasts up to 16 days in advance, but with decreasing spatial and temporal resolution over time. It is widely accepted that beyond 7 days the forecast is very general and not very accurate.
The model is run in two parts: the first part has a higher resolution and goes out to 180 hours (7 days) in the future, the second part runs from 180 to 384 hours (16 days) at a lower resolution. The resolution of the model varies in each part of the model: horizontally, it divides the surface of the earth into 35 or 70 kilometre grid squares; vertically, it divides the atmosphere into 64 layers and temporally, it produces a forecast for every 3rd hour for the first 180 hours, after that they are produced for every 12th hour.
This is the only global model for which all output is available, for free, over the internet (as a result of U.S. law), and as such is the basis for non-state weather companies."
De upgrade:
EFFECTIVE JUNE 22 2010...BEGINNING WITH THE 1200 COORDINATED UNIVERSAL TIME /UTC/ RUN...THE NATIONAL CENTERS FOR ENVIRONMENTAL PREDICTION /NCEP/ WILL UPGRADE THE GLOBAL FORECAST SYSTEM /GFS/. THE RESOLUTION OF THE GLOBAL FORECAST MODEL WILL BE INCREASED FROM T382 /35 KM/ TO T574 /27 KM/.
THE HIGH RESOLUTION PORTION OF THE FORECAST WILL BE EXTENDED FROM 180 HRS TO 192 HRS. WITH THIS EXTENSION 3 HOURLY OUTPUT WILL BE MADE AVAILABLE OUT TO 192 HOURS.
THIS WILL RESULT IN SIGNIFICANT CHANGES IN THE DEFINITION OF PARAMETERS IN THE 192 HOUR PRESSURE GRIB /PGRB/ AND FLUX FILES. THERE WILL ALSO BE SIGNIFICANT CHANGES IN MODEL PHYSICS ASSOCIATED WITH THIS CHANGE. IN ADDITION MODIFICATIONS WILL BE MADE TO THE CONTENTS OF THE GLOBAL DATA ASSIMILATION SYSTEM /GDAS/ AND GFS PGRB FILES.
CHANGES IN MODEL PHYSICS INCLUDE:
RADIATION AND CLOUD OVERLAP
GRAVITY WAVE DRAG
HURRICANE RELOCATION
NEW PLANETARY BOUNDARY LAYER SCHEME
NEW MASS FLUX SHALLOW CONVECTION
UPDATED DEEP CONVECTION SCHEME
POSITIVE DEFINITE TRACER TRANSPORT SCHEME
THE NEW PARAMETER FOR THE GFS FORECAST PRESSURE GRIB FILES IS:
MAX WIND GUST
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