Merge levels
Added by Waheed Iqbal over 10 years ago
Hello
Cdo version is :
cdo -V
Climate Data Operators version 1.6.2rc3 (http://code.zmaw.de/projects/cdo)
and OS is Fedora 19:
I am unable to merge four files of uwind into a single file that will have four pressure levels.
Here are the details:
Input files:
file1_925.nc (has variable ua925 0 t,y,x Eastward Wind)
file2_850.nc (has variable ua825 0 t,y,x Eastward Wind)
file3_500.nc (has variable ua500 0 t,y,x Eastward Wind)
file4_200.nc (has variable ua200 0 t,y,x Eastward Wind)
Desired Output file:
I want a file file_final.nc (variable ua 4 t,z,y,x Eastward Wind)
I have tried merge, cat etc but they do not serve the purpose.
Please help me to solve this problem?
Thanks in advance.
Waheed
Replies (2)
RE: Merge levels - Added by Matt Thompson over 10 years ago
Waheed,
"cdo merge" worked for me. I took a file with around 48 levels of U and split them apart with "splitlevel". I then took 6 of these:
$ ls Ulev00000*
Ulev000001.nc4 Ulev000002.nc4 Ulev000003.nc4 Ulev000004.nc4 Ulev000005.nc4 Ulev000007.nc4
$ cdo infon Ulev000001.nc4
-1 : Date Time Level Gridsize Miss : Minimum Mean Maximum : Parameter name
1 : 2000-04-15 00:00:00 1 16380 0 : -11.440 25.533 83.944 : U
cdo infon: Processed 16380 values from 1 variable over 1 timestep ( 0.00s )
$ cdo merge Ulev00000* comboU.nc4
cdo merge: Processed 98280 values from 6 variables over 6 timesteps ( 0.01s )
$ cdo info comboU.nc4
-1 : Date Time Level Gridsize Miss : Minimum Mean Maximum : Parameter ID
1 : 2000-04-15 00:00:00 1 16380 0 : -11.440 25.533 83.944 : -1
2 : 2000-04-15 00:00:00 2 16380 0 : -18.550 19.201 65.850 : -1
3 : 2000-04-15 00:00:00 3 16380 0 : -24.682 13.400 60.121 : -1
4 : 2000-04-15 00:00:00 4 16380 0 : -31.325 8.5258 54.017 : -1
5 : 2000-04-15 00:00:00 5 16380 0 : -39.248 6.0766 50.995 : -1
6 : 2000-04-15 00:00:00 7 16380 0 : -43.078 3.6568 47.119 : -1
cdo info: Processed 98280 values from 1 variable over 1 timestep ( 0.00s )
Is your cdo returning an odd error?
Matt
RE: Merge levels - Added by Waheed Iqbal over 10 years ago
Hi Matt
I tried "cdo merge", no error is returned. The detail of the procedure that I adopted is as following:
I used
cdo merge file1_925.nc file2_850.nc file3_500.nc file4_200.nc out1.nc cdo merge: Processed 2609360 values from 4 variables over 104 timesteps ( 0.16s)
this out1.nc has four variables (as each file had different name of variable) and only one z level (level=0).
To overcome the problem of different names in each file, I changed the variable of each file to "u" by using the
cdo command "cdo chname" and then executed the command:
$ cdo merge file_925.nc file_850.nc file_500.nc file_200.nc out3.nc cdo merge (Warning): Duplicate entry of parameter u in file_850.nc! cdo merge: Processed 2609360 values from 4 variables over 104 timesteps ( 0.14s )
This out2.nc file has one variable at 4 levels (but when i set set z lev 1 (or 2,3,4) grads returns "LEV set to 0 0 ").
also I am unable to display the variable, here is the error message from Grads:
ga-> d u
Data Request Error: Invalid grid coordinates
World coordinates convert to non-integer grid coordinates
Variable = u Dimension = 2
Error ocurred at column 1
DISPLAY error: Invalid expression
Expression = u
I guess the problem is that my input files do not have the z co-ordinates (as you can see the variable: ua850 0 ,t,y,x) and in your case z coordinate will be present: you have splitted the levels from a file which had the z coordinate and hence the "cdo merge" command worked for you!
If I ncdump or cdo sinfo any input file the level is "0" (surface) but in actual that is not the case!
May be it will be required to first add the z coordinate to each file and then merge?
Any help/suggestions will be greatly appreciated.
Waheed