Data field inventory & file name interpretation

Prefix   VARIABLE                             TYPE  UNITS      COMMENTS
------   --------                             ----  -----      --------

ALL      Contains many quantities
         (use wgrib to see file inventory)
BVF2     Brunt-Vaisala frequency squared       0    1/s**2      6
CBUQ     Covariance between u and q            0    m/s*gm/gm   5
CBTZW         "     between u and T            0    K*m/s       5
CBMZW         "     between u and v            0    m**2/s**2   5
CBQW          "     between q and VVEL         0    m/s*gm/gm   1,4,6
CBTMW         "     between v and T            0    K*m/s       5  
CBTW          "     between T and VVEL         0    K*Pa/s      1,4,6  
CBUW          "     between u and VVEL         0    Pa/s*m/s    1,4,6
CBVQ          "     between v and q            0    m/s*gm/gm   5  
CBVW          "     between v and VVEL         0    m/s*Pa/s    1,4,7  
CFNLF    Cloud forcing net long wave flux      A    W/m**2      1,2
CFNSF    Cloud forcing net solar flux          A    W/m**2      1,2
CPRAT    Convective precipitation rate         A    kg/m**2/s   1,2,3,4
DSWRF    Downward solar radiation flux         A    W/m**2      1,2
GPCPRAIN GPCP precipitation est                -    kg/m**2/s   7
HGT      Geopotential height (Z)               0    gpm         5
ICEC     Ice concentration (ice=1; no ice=0)   -    fraction    7
LAND     Land-sea mask (1=land; 0=sea)         -    ----        7
LHTFL    Latent heat flux                      A    W/m**2      1,2,3,4
MNTSF    Montgomery stream function            0    m**2/s**2   6
MRDGRAIN merged precipitation est              -    kg/m**2/s   7
NLWRS    Net long wave radiation (surface)     A    W/m**2      1,2   
NSWRS    Net short wave radiation (surface)    A    W/m**2      1,2,4
PEVPR    Potential evaporation rate            A    W/m**2      6
POT      Potential temperature                 0    K           1,2,3,4
PRATE    Total Precipitation rate              A    kg/m**2/s   1,2,3,4
PRES     Pressure                              06   Pa          5
PV       Potential vorticity                   0    m**2/s/kg   6
PWAT     Precipitable water                    06   kg/m**2     5
RH       Relative humidity                     0    percent     5
RUNOF    Runoff                                A    kg/m**2     1,3,4
SHTFL    Sensible heat flux                    A    W/m**2      1,2,3,4
SOILW    Volumetric soil moisture content      6    fraction    3
SPFH     Specific humidity (q)                 06   kg/kg       5
STREAM   Stream function                       0    m**2/s      6
TCDC     Total cloud cover                     A    percent     1
TMP      Temperature (T)                       06A  K           5,9
TMP      sea surface temperature (SST)         -    K           7
UFLX     Zonal wind stress (negative)          A    N/m**2      4,10
UGRD     Zonal Wind (u)                        06   m/s         5
ULWRF    Upward long wave radiation flux       A    W/m**2      1,2
ULWRF    Upward long wave radiation flux       -    W/m**2      7
UMAS     Mass weighted zonal wind              0    gm/m*K*s    5
USWRF    Upward solar radiation flux           A    W/m**2      1,2
VFLX     Meridional wind stress (neg)          A    N/m**2      4,10
VGRD     Meridional Wind (v)                   06   m/s         5
VMAS     Mass weighted meridional wind         0    gm/m*K*s    5
VPOT     Velocity potential                    0    m**2/s      6
VVEL     Pressure vertical velocity            0    Pa/s        1,6
WEASD    Water equiv. of accum. snow depth     %6   kg/m**2     8
XPRATE   corrected precipitation               A    kg/m**2/s   1,2,3,4

0=at analysis time
6=6 hour forecast
A=0-6 hour accumulation or average of forecast starting from the analysis
*=minimum or maximum in either a 6 or 24 window.
%=combination of observations and forecast
-=observed field


1. cloud/convection parameterization dependent
2. radiation model dependent (include reflection, scattering)
3. soil/surface parameterization dependent
4. boundary layer parameterization dependent
5. observed quantity analyzed by model
6. derived quantity from assimilation
7. observed quantity
8. snow coverage heavily determined by observations & forecasts
   (depth is not observed and is crudely estimated, see TEXT\DETAILS\SNOW)
9. temperature at mean sea level is observed sea surface temperature
10. upward fluxes in GRIB are positive (unlike convention)


Inhomogeneous sampling/quality in troposphere, stratosphere and boundary layer
affect the quality of the analyses.  In regions with few observations, the 
analyses tend to be biased towards the climatology of the GCM used to make the 
"first guess".  Most quantities in the boundary layer are strongly influenced 
by physical parameterizations of boundary layer, cloud, radiation, surface 
properties, vegetation and soil.  In general, the best analyzed quantities are 
the tropospheric winds, geopotential heights and temperatures over land.
The radiation quantities are heavily dependent on the PREDICTED cloud cover.  
Precipitation is the 0 to 6 hour forecast from the model (not determined by 
rain gauges).