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  Weather: Global fcst

ASP: Atmosphere-Surface Prediction system


Global Domain


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Real Time Standard Forecast Plots of Interest

Select plots can be seen here for the global domain: the model is still in test mode, so there could be an occasional missed forecast or outputs to be improved upon. The model uses a platte-carre projection (lat-lon) on a (finite difference) C-grid. Currently, runs are usually done on grids of (degrees, lon X lat):

  • 0.93750 X 0.75000 (default, about 80x80km at mid latitudes),
  • 1.12500 X 0.84375... or
  • 1.40625 X 1.12500 or
  • 1.87500 X 1.40625

See plots to know which resolution was used for the current forecast (indicated in upper right part of plots). Above a critical latitude, Fourier Filtering (polar filtering) of mass variables is used (i.e. the product of the specific density and T, u, v are filtered, along with psurf). The latitudinal grid spacing has been selected such that grid boxes are approximately squares at the cut-off latitude (generally in mid-latitudes). The initial fields and 3.5 day forecasts (0 to 84 hour forcasts, every 12 hours) can be seen below by clicking on the appropriate links (below). The model uses the same physics and dynamic core as the limited area model version of ASP. The global model uses a larger grid spacing than the LAM model, so fields are slightly more smooth. The model is initialized using input GFS data (interpolated to the ASP grid), and a short forward and backward adiatatic integration using a digital filter. The model uses big-brother assimilation of T, u, v and psurf during the first 12h of the forecast (using GFS forecast data), which is then tapered off by 18h. The description of the global grid, polar filtering, boundary conditions etc...can be found in the ASP documentation pages.

Feel free to send any comments (aaron.a.boone@gmail.com).


Sub Domains

Several sub domains on the global grid are shown: NA=North America, EU=Europe, AF=Africa, and EA=East Asia. Hemisphere=a satellite view of a hemisphere (using an Orthographic Projection). The Default is centered over the central north Atlantic. Note that global plots might, at times, extend beyond the 3.5 default forecast (out to 5, 7 or even 10 days).


Field NANA EUEU EAEA AFAFHemisphere
300 Hgt, WindV, WindS 0-36h 48-84h 0-36h 48-84h 0-36h 48-84h 0-36h 48-84h 0-84h
500 Hgt, WindV, AbsVort 0-36h 48-84h 0-36h 48-84h 0-36h 48-84h 0-36h 48-84h 0-84h
700 Hgt, WindV, VVel 0-36h 48-84h 0-36h 48-84h 0-36h 48-84h 0-36h 48-84h 0-84h
850 Hgt, WindV, Tair 0-36h 48-84h 0-36h 48-84h 0-36h 48-84h 0-36h 48-84h 0-84h
Lowest model level T, RH, and wind vectors 0-36h 48-84h 0-36h 48-84h 0-36h 48-84h 0-36h 48-84h
PSurf, Total Precip, 500-1000 Thck 0-36h 48-84h 0-36h 48-84h 0-36h 48-84h 0-36h 48-84h 0-84h
PSurf, Froz Precip, 5400m Thck, 850mb-0deg 0-36h 48-84h 0-36h 48-84h 0-36h 48-84h 0-36h 48-84h
700 Hgt, 850-500 mb RHavg 0-36h 48-84h 0-36h 48-84h 0-36h 48-84h 0-36h 48-84h
500 Hgt, Surface Pressure 0-36h 48-84h 0-36h 48-84h 0-36h 48-84h 0-36h 48-84h 0-84h

    Key:
  • Hgt = Geopotential Height (m)
  • WindS = Wind speed
  • WindV = Wind vectors
  • Tair = Air Temperture
  • AbsVort = Absolute Vorticity
  • VVel = Vertical velocity defined as -omega (+ for upward motion)
  • Qair = Specific Humidity
  • Precip = Cummulative total (convective and stratiform) Precipitation for each forecast interval
  • Thck = Pressure thickness
  • Lowest Model Level = Currently corresponds to eta=0.997 or about 30 m above the ground (less in high altitude zones)
  • Near-Surf = 2m Tair and 10m Wind speed (i.e. at the level of standard measurements)
  • TSurf = Surface temperature: combined surface vegetation and upper thin soil layer or SST (Sea Surface Temp.)

Standard Atmosphere: Pressure-Height correspondence

As a reference, the pressure levels above correspond to the approximate heights below in meters (and feet) for a standard atmosphere. This can be used as a rough estimate of the height of the dust plumes shown in the plots above.

Pressure (HPa or mb) height (meters)height (feet)
100 16170 53051
200 11770 38616
300 9160 30053
500 5570 18274
700 3000 9843
850 1460 4790
925 760 2493
1013.25 0 0

Please send any comments to aaron.a.boone@gmail.com



Disclaimer

Please note that this page has nothing to do with my employer, CNRS, or where I am employed, at the National Center for Meteorological Research (Centre National de Recherches Meteorologiques: CNRM) at Meteo-France. The opinions expressed herein are my own, and are not a reflection of those where I work or of my employer.

Acknowledgement

Finally, a special thanks is extended to the United States National Centers for Environmental Prediction (NCEP) for making GFS analysis and forecast data freely available in near real time, which makes applications and research such as this possible.