The data if available on spectral grid or gaussian grid, needs to be remapped onto a regular lat lon grid, so that it can be analysed using Met.3D. The following code snippet provides a minimal example to perform the remapping.

#!/bin/bash

#####################################################################################
# Minimal examples of basic CDO commands for remapping ERA5 data onto a regular grid 
#
# Link to the Met.3D documentation
# https://collaboration.cen.uni-hamburg.de/display/Met3D/Welcome+to+Met.3D
#
# Link to the cdo documentation 
# https://code.mpimet.mpg.de/projects/cdo/wiki/Cdo#Documentation
#
# Link to a cdo reference sheet
# https://code.mpimet.mpg.de/projects/cdo/embedded/cdo_refcard.pdf
#
#####################################################################################


###########
# define path to the folder storing the ERA5 data as provided by the ECMWF
# (GRIB data with spatial coordinate systems "Gaussian Grid" or "Spherical Harmonics")
DATAFOLDER=/path/to/ERA5-data-folder/


##########
# define path to the folder for storing the remapped ERA5 data-files
POSTPROCESSEDDATAFOLDER=/path/to/Results-Folder/
mkdir -p ${POSTPROCESSEDDATAFOLDER}


##########
# define path to a file characterizing the grid to which the ERA5 data will be remapped
TARGETGRIDFILE=/path/to/targetgridfile.txt

# See below for an examplar gridFile for remapping with CDO to a regular lat-lon grid : 
# --> "cdo_gridFile_regular_LatLon_minimalExample.txt"


##########
# define input and output data files	
INFILE=/path/to/ERA5_Data_File
OUTFILE=/path/to/ERA5_Data_on_regular_grid

	
##########	
# bilinear remapping from reduced Gaussian grid to regular Lat-Lon grid 
# and conversion from GRIB to NETCDF
cdo -f nc4 -remapbil,${TARGETGRIDFILE} -setgridtype,regular ${OUTFILE} ${INFILE}


##########
# bilinear remapping from spectral grid to Gaussian grid to regular Lat-Lon grid
cdo -f nc4 -remapbil,${TARGETGRIDFILE} -sp2gpl ${INFILE} ${OUTFILE}

The contents of the 'cdo_gridFile_regular_LatLon_minimalExample.txt' in this example are as below:

gridtype = lonlat
gridsize = 90381
xsize = 641
ysize = 141
xfirst = -80
xinc = 0.25
yfirst = 85
yinc = -0.25
  • No labels