[ncl-talk] reading in ERA-20C grib file with data on model/hybrid levels
De Vries Andries
andries.devries at env.ethz.ch
Tue Mar 12 07:28:48 MDT 2019
Hi Dennis,
Thank you very much. The newer version of NCL helps indeed, hadn't thought of that simple solution. However, still I miss a few coordinate variables that I can read in the netcdf file, but not in the original grib file; the hyam and hybm variabels. Please, see the print statement of the netcdf file below. Any idea why and what can help?
Cheers,
Andries
Variable: b2
Type: file
filename: e20c_an_temp_r360x180_ml_199410
path: ../ERA20C-MOD/NC/e20c_an_temp_r360x180_ml_199410.nc
file global attributes:
CDI : Climate Data Interface version 1.9.5 (http://mpimet.mpg.de/cdi)
Conventions : CF-1.6
history : Thu Feb 14 11:02:46 2019: cdo -f nc copy /atmosdyn/devriesa/DATA/ERA20C/e20c_an_temp_r360x180_ml_199410.grib /atmosdyn/devriesa/DATA/ERA20C-MOD/NC/e20c_an_temp_r360x180_ml_199410.nc
institution : European Centre for Medium-Range Weather Forecasts
CDO : Climate Data Operators version 1.9.5 (http://mpimet.mpg.de/cdo)
dimensions:
time = 124 // unlimited
lon = 360
lat = 181
lev = 91
nhyi = 92
nhym = 91
variables:
double time ( time )
standard_name : time
units : hours since 1994-10-1 00:00:00
calendar : proleptic_gregorian
axis : T
double lon ( lon )
standard_name : longitude
long_name : longitude
units : degrees_east
axis : X
double lat ( lat )
standard_name : latitude
long_name : latitude
units : degrees_north
axis : Y
double lev ( lev )
standard_name : hybrid_sigma_pressure
long_name : hybrid level at layer midpoints
formula : hyam hybm (mlev=hyam+hybm*aps)
formula_terms : ap: hyam b: hybm ps: aps
units : level
positive : down
double hyai ( nhyi )
long_name : hybrid A coefficient at layer interfaces
units : Pa
double hybi ( nhyi )
long_name : hybrid B coefficient at layer interfaces
units : 1
double hyam ( nhym )
long_name : hybrid A coefficient at layer midpoints
units : Pa
double hybm ( nhym )
long_name : hybrid B coefficient at layer midpoints
units : 1
float t ( time, lev, lat, lon )
standard_name : air_temperature
long_name : Temperature
units : K
param : 0.0.0
________________________________________
From: Dennis Shea [shea at ucar.edu]
Sent: 12 March 2019 13:09
To: De Vries Andries
Cc: ncl-talk at ucar.edu
Subject: Re: [ncl-talk] reading in ERA-20C grib file with data on model/hybrid levels
I am using NCL 6.5.0. I have no problem reading the grib file.
%> ncl
NCAR Command Language Version 6.5.0
ncl 0> f = addfile("e20c_an_temp_r360x180_ml_199410.grib","r")
ncl 1> print(f)
ncl 2> t = f->TMP_P0_L105_GLL0
printVarSummary(t)
ncl 3> printVarSummary(t)
Variable: t
Type: float
Total Size: 2941061760 bytes
735265440 values
Number of Dimensions: 4
Dimensions and sizes: [initial_time0_hours | 124] x [lv_HYBL0 | 91] x [lat_0 | 181] x [lon_0 | 360]
Coordinates:
initial_time0_hours: [1707120..1707858]
lv_HYBL0: [ 1..91]
lat_0: [90..-90]
lon_0: [ 0..359]
Number Of Attributes: 11
center : European Center for Medium-Range Weather Forecasts
production_status : Operational products
long_name : Temperature
units : K
_FillValue : 1e+20
grid_type : Latitude/longitude
parameter_discipline_and_category : Meteorological products, Temperature
parameter_template_discipline_category_number : ( 0, 0, 0, 0 )
level_type : Hybrid level
forecast_time : 0
forecast_time_units : hours
ncl 4> printMinMax(t,0)
(0) Temperature (K) : min=170.211 max=313.993
On Tue, Mar 12, 2019 at 5:30 AM De Vries Andries <andries.devries at env.ethz.ch<mailto:andries.devries at env.ethz.ch>> wrote:
Dear NCL Team & Users,
I have an issue with reading in ERA-20C grib files from ECMWF that contain data on model levels. No matter if it is data on a regular (1x1 degree grid) or a gaussian grid (N80), I can not read the variables within the file, see for example the first print statements below.
When I convert the grib file to netcdf format, using the tool cdo {cdo -f nc copy {infile} {outfile}}, there is no problem; I can read in the netcdf file and variables without any problem, see the second print statement below. Ideally, however, I would like to use NCL to read in the grib files without converting them first to netcdf format. Any idea how to achieve this?
Two side comments (1) I can read in ERA-20C grib files with data on pressure levels, surface, or isentropic levels without any problem problem; there is no need to convert them to netcdf format, and (2) Also, I can read in ERA-Interim grib files with data on model levels without any problems that are downloaded in the same manner & format as the ERA-20C data.
@NCL TEAM; I copied an example ERA-20C file in grib and netcdf format with temperature on model levels for the year 199410 to ftp.cgd.ucar.edu<http://ftp.cgd.ucar.edu>
Kind regards,
Andries
-----------------------------------------------------------------------------------------------------------------------------------------------------------------
READING IN ERA-20C GRIB FILE WITH DATA ON MODEL LEVELS; CANNOT READ VARIABLES
-----------------------------------------------------------------------------------------------------------------------------------------------------------------
Copyright (C) 1995-2015 - All Rights Reserved
University Corporation for Atmospheric Research
NCAR Command Language Version 6.3.0
The use of this software is governed by a License Agreement.
See http://www.ncl.ucar.edu/ for more details.
ncl 0> a=addfile("e20c_an_temp_r360x180_ml_199410.grib","r")
ncl 1> print(a)
print(a)
Variable: a
Type: file
filename: (null)
path: e20c_an_temp_r360x180_ml_199410.grib
file global attributes:
dimensions:
variables:
-----------------------------------------------------------------------------------------------------------------------------------------------------------------
READING IN ERA-20C NETCDF FILE WITH DATA ON MODEL LEVELS; READS VARIABLES
-----------------------------------------------------------------------------------------------------------------------------------------------------------------
Copyright (C) 1995-2015 - All Rights Reserved
University Corporation for Atmospheric Research
NCAR Command Language Version 6.3.0
The use of this software is governed by a License Agreement.
See http://www.ncl.ucar.edu/ for more details.
ncl 0> a=addfile("e20c_an_temp_r360x180_ml_199410.nc<http://e20c_an_temp_r360x180_ml_199410.nc>","r")
ncl 1> print(a)
Variable: a
Type: file
filename: e20c_an_temp_r360x180_ml_199410
path: e20c_an_temp_r360x180_ml_199410.nc<http://e20c_an_temp_r360x180_ml_199410.nc>
file global attributes:
CDI : Climate Data Interface version 1.9.5 (http://mpimet.mpg.de/cdi)
Conventions : CF-1.6
history : Thu Feb 14 11:02:46 2019: cdo -f nc copy /atmosdyn/devriesa/DATA/ERA20C/e20c_an_temp_r360x180_ml_199410.grib /atmosdyn/devriesa/DATA/ERA20C-MOD/NC/e20c_an_temp_r360x180_ml_199410.nc<http://e20c_an_temp_r360x180_ml_199410.nc>
institution : European Centre for Medium-Range Weather Forecasts
CDO : Climate Data Operators version 1.9.5 (http://mpimet.mpg.de/cdo)
dimensions:
time = 124 // unlimited
lon = 360
lat = 181
lev = 91
nhyi = 92
nhym = 91
variables:
double time ( time )
standard_name : time
units : hours since 1994-10-1 00:00:00
calendar : proleptic_gregorian
axis : T
double lon ( lon )
standard_name : longitude
long_name : longitude
units : degrees_east
axis : X
double lat ( lat )
standard_name : latitude
long_name : latitude
units : degrees_north
axis : Y
double lev ( lev )
standard_name : hybrid_sigma_pressure
long_name : hybrid level at layer midpoints
formula : hyam hybm (mlev=hyam+hybm*aps)
formula_terms : ap: hyam b: hybm ps: aps
units : level
positive : down
double hyai ( nhyi )
long_name : hybrid A coefficient at layer interfaces
units : Pa
double hybi ( nhyi )
long_name : hybrid B coefficient at layer interfaces
units : 1
double hyam ( nhym )
long_name : hybrid A coefficient at layer midpoints
units : Pa
double hybm ( nhym )
long_name : hybrid B coefficient at layer midpoints
units : 1
float t ( time, lev, lat, lon )
standard_name : air_temperature
long_name : Temperature
units : K
param : 0.0.0
_______________________________________________
ncl-talk mailing list
ncl-talk at ucar.edu<mailto:ncl-talk at ucar.edu>
List instructions, subscriber options, unsubscribe:
http://mailman.ucar.edu/mailman/listinfo/ncl-talk
More information about the ncl-talk
mailing list