These NCEP FNL (Final) operational global analysis and forecast data
are on 0.25-degree by 0.25-degree grids prepared operationally every
six hours. This product is from the Global Data Assimilation System
(GDAS), which continuously collects observational data from the
Global Telecommunications System (GTS), and other sources, for many
analyses. The FNLs are made with the same model which NCEP uses in
the Global Forecast System (GFS), but the FNLs are prepared about an
hour or so after the GFS is initialized. The FNLs are delayed so
that more observational data can be used. The GFS is run earlier in
support of time critical forecast needs, and uses the FNL from the
previous 6 hour cycle as part of its initialization.
The analyses are available on the surface, at 26 mandatory (and
other pressure) levels from 1000 millibars to 10 millibars, in the
surface boundary layer and at some sigma layers, the tropopause and
a few others. Parameters include surface pressure, sea level
pressure, geopotential height, temperature, sea surface temperature,
soil values, ice cover, relative humidity, u- and v- winds, vertical
motion, vorticity and ozone.
The archive time series is continuously extended to a near-current
date. It is not maintained in real-time.