Skip Navigation Links www.nws.noaa.gov 
NOAA logo - Click to go to the NOAA home page National Weather Service   NWS logo - Click to go to the NWS home page
Climate Prediction Center
 
 

 
About Us
   Our Mission
   Who We Are

Contact Us
   CPC Information
   CPC Web Team

 
HOME > Monitoring_and_Data > Oceanic and Atmospheric Data > Reanalysis: Atmospheric Data > wgrib2-grid
 

wgrib2: -grid

Introduction

The -grid option prints out the grid information.

-sh-2.05b$ wgrib2 new.grb2 -s -grid
1:0:d=2005082812:HGT:1000 mb:78 hour fcst:grid_template=0:
        lat-lon grid:(360 x 181) units 1e-06 scan WE:NS res 48
        lat 90 to -90 by 1
        lon 0 to 359 by 1

Staggered Grids, wgrib2 2.0.8+

Staggered grids are often used in grid point (as opposed to spectral) atmospheric models. (Arakawa, A.; Lamb, V.R. (1977). "Computational design of the basic dynamical processes of the UCLA general circulation model". Methods in Computational Physics: Advances in Research and Applications. 17: 173–265.) There are advantages in storing the model grids in grib for both the modeler and the user. The advantages are compactness, and a standard format. The user also has the advantage of eliminating an extra interpolation step. The staggering information is stored in the last 4 bits of flag table 3.4. If these bits are all zero, there is no staggering.

Staggered grids in GRIB work by

  1. A "fundamental" grid is defined
  2. staggered grid could have an 0 dx offset in the X direction
  3. or staggered grid could have an 1/2 dx offset in the X direction
  4. or staggered grid could have 0 dx offset for odd rows and 1/2 dx for even rows (all in the X direction)
  5. staggered grid could have an 0 dy offset in the Y direction
  6. or staggered grid could have an 1/2 dy offset in the Y direction
  7. staggered grid could have fewer points in the row or column if the offset is non-zero
This scheme allows encoding the Arakawa A-E Egrids. The wgrib2 -grid will show the staggering. The storage description was updated in v2.0.8 to be
  1. nx*ny: length of the row is nx, there are ny rows
  2. nx*(ny-1): length of the row is nx, there are ny-1 rows
  3. trim-x*ny: length of the row is either nx or nx-1, there are ny rows
  4. trim-x*(ny-1): length of the is either nx or nx-1, there are ny-1 rows

Usage

-grid
See also: -nxny, -nlons

NOAA/ National Weather Service
National Centers for Environmental Prediction
Climate Prediction Center
5830 University Research Court
College Park, Maryland 20740
Climate Prediction Center Web Team
Page last modified: May 15, 2005, updated Nov 29, 2018
Disclaimer Privacy Policy