I have downloaded monthly mean wind speed of terraclimate data for 20 years (2000-2019) which have NetCDF format, but unfortunately, each year has a single NetCDF file, and I want to merge them all to have a single wind speed which is from 2000 to 2019. So, I am using xarray in python to join these NETCDF files, and this is my code:
import xarray as xr
import glob
ds = xr.open_mfdataset("C:\Users\Nazanin\Desktop\other\nc*.nc")
ds.to_netcdf('Final.nc')
but it gives me this error:
Exception has occurred: ValueError
Variable 'ws' has conflicting _FillValue (32768) and missing_value (-32768). Cannot encode data.
File "C:\Users\Nazanin\Desktop\other\nc\nc.py", line 4, in
ds.to_netcdf('Final.nc')
Could anybody help me to fix this problem?
As far as I know "missing_value" and "_FillValue" both should be the same by definition, but it being different wont affect the merging process if done in another way.
There are 2 solutions you can try out depending on what suits you,
1) Firstly, I would suggest you performed the merging of NetCDF files with Climate Data Operators (cdo) itself. You could just achieve it in 1 or 2 lines.
Just browse to the directory consisting of all the ".nc" files.
cdo mergetime *.nc Output.nc
The "Output.nc" will have all the merged data irrespective of the different missing/fill values.
(OR)
Now there is no function in python with which you can explicitly modify the "_FillValue" or "_missing_value" of all these Netcdf files, You might have to extract the variables one by one into a python object, then bind them and create a new Netcdf file. That would take a lot of time as well as a lengthy code to write, I've done it in R, So I am sure that the second method works perfectly.
2) I've attached an R script along with this Answer that merges all the "Netcdf" files in a DIRECTORY given that all the NC files have the same latitude and longitude dimensions.
Just Install R and Rstudio and Open the R script in it.
You'll have to change the following line in the Script in Section 2.
SEC 2 : Change the Path of the DIRECTORY to "C:\Users\Nazanin\Desktop\other\"
which is where all your nc files are.
Both these methods work like a charm (although the 2nd one is better) and in case if there's still an issue, you could just share your NetCDF file(s) here and I'll see if there is any other alternative method.
Mohammed Cassim Sannan Thank you for your help. I have another question. I have six CSV files which I have sent in this link (https://drive.google.com/drive/folders/1GQtyY1mI1YrK8GFP9SEo7dZfFHexKro3?usp=sharing). If you open them you will understand that each of these files has 720 rows and 360 columns which indicates longitude and latitude respectively. I should tell you that the first point of latitude is -89.75, the first point of longitude is -179.75, and the resolution of these data is 0.5 degrees. I want to convert them to a NetCDF file which has the following properties:
Dimensions:
longitude = 720
latitude = 360
time = 6
Variables:
longitude
Size: 720x1
Dimensions: longitude
Datatype: single
Attributes:
long_name = 'longitude'
units = 'degrees_east'
latitude
Size: 360x1
Dimensions: latitude
Datatype: single
Attributes:
long_name = 'latitude'
units = 'degrees_north'
time
Size: 6x1
Dimensions: time
Datatype: single
Attributes:
long_name = 'time'
units = 'days since 1900-1-1'
calendar = 'gregorian'
tmp
Size: 720x360x6
Dimensions: longitude, latitude,time
Datatype: single
Attributes:
long_name = 'monthly mean temperature'
units = 'degrees Celsius'
correlation_decay_distance = 1200
_FillValue = 9.969209968386869e+36
missing_value = 9.969209968386869e+36
Could you please help me?
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