The COPYGB grid definition parameters for Lambert Conformal grids are listed below:
copygb -g"255 3 NX NY STARTLAT STARTLON 8 CENLON DX DY POLE 64 TRUELAT1 TRUELAT2" -x in.grb out.grb
| where | ||
| 255 3 | User-defined Lambert Conformal grid | |
| NX | Number of points on latitude circle | |
| NY | Number of points on longitude meridian | |
| STARTLAT | Southwest corner latitude * 1000 (lat = -90 ... 90) | |
| STARTLON | Southwest corner longitude * 1000 (lon = -180 ... 180) | |
| 8 | ||
| CENLON | Center longitude * 1000 | |
| DX | Longitudinal increment in meters | |
| DY | Latitudinal increment in meters | |
| POLE | Northern (0) or southern (128) hemisphere | |
| 64 | ||
| TRUELAT1 | First true latitude * 1000 | |
| TRUELAT2 | Second true latitude * 1000 |
Please note that all of the grid definition parameters must be integers. All latitude and longitude values are given in thousandths of a degree. The grid increments are given in meters.
User-Defined Lambert Conformal Grid
Rather than defining a Lambert Conformal manually, we'll use the output of wgrib to define the grid we'd like to use. Let's look again at the wgrib output for NCEP grid 212:
Here is the grid definition:
Lambert Conf: Lat1 12.190000 Lon1 -133.459000 Lov -95.000000
Latin1 25.000000 Latin2 25.000000 LatSP 0.000000 LonSP 0.000000
North Pole (185 x 129) Dx 40.635000 Dy 40.635000 scan 64 mode 8
Translate this definition to the COPYGB grid specification as follows:
- NX = 185
- NY = 129
- STARTLAT = 12190
- STARTLON = -133459
- CENLON = -95000
- DX = 40635
- DY = 40635
- TRUELAT1 = 25000
- TRUELAT2 = 25000
Plug these numbers into the grid specification and run COPYGB follows:
-xg"255 3 185 129 12190 -133459 8 -95000 40635 40635 0 64 25000 25000" \
$MET_TUTORIAL_DATA/input/sample_fcst/2009123112/arw-fer-gep1/d01_2009123112_02400.grib \
$MET_TUTORIAL_DATA/output/copygb/d01_2009123112_02400.grib_lambert
Lastly, run wgrib on the COPYGB output and make sure the grid matches the one listed above:
