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1.ATMOSPHERIC MODEL
ECMWF produces routine global analyses for the four main synoptic hours
00, 06, 12 and 18 UTC and global 10-day forecasts based on 12 UTC data
1.1 Model:
| Numerical scheme |
T213L31 (triangular truncation, resolving 213 waves
around a great circle on the globe; 31 levels between the earth's
surface and 30 km), Semi-Lagrangian formulation |
| Smallest wavelength resolved |
190 km Time-step: 15 minutes |
| Number of grid points in model |
4,154,868 |
| Variables at each grid point (recalculated
at each time-step) |
Wind, temperature, humidity (also pressure at surface
grid-points) |
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Included in model
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orography (terrain height, US Navy data-set,
10 minutes of arc resolution), three surface and sub-surface levels
(allowing for vegetation cover, gravitational drainage, capillarity
exchange, surface and sub-surface runoff, deep-layer soil temperature
and moisture), clouds (high, medium, low, convective), stratiform
and convective precipitation, carbon dioxide (345 ppmv fixed),
aerosol, ozone, solar angle, diffusion, ground & sea roughness,
ground and sea-surface temperature, ground humidity, snow-fall, snow-cover
& snow melt, radiation (incoming short-wave and out-going
long-wave), friction (at surface and in free atmosphere), gravity
wave drag, evaporation, sensible latent heat flux. |
1.2 Data assimilation:
| Analysis of |
Mass & wind (three-dimensional multi-variate analysis
on 31 model levels) Humidity (three-dimensional on model levels up
to 250 hPa)
Surface parameters (sea surface temperature from NMC Washington analysis
- update daily), soil water content, snow depth |
| Initialization |
by use of the normal modes of free oscillation of the
model atmosphere |
| Data used |
Global satellite data (SATOB, TOVS, SATEM), Global
free-data (AIREP, AMDAR, TEMP, PILOT), Oceanic data (SYNOP/SHIP, PILOT/SHIP,
TEMP/SHIP, DRIBU), Land data (SYNOP). (40,000 observational data are
used in each analysis. Data checking and validation is applied to
each parameter used.) |
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