how to convert Grib1 to Netcdf using R?

问题

I have just downloaded some climate data in grib format. I want to use "R" to convert it to NetCDF format.

Furthermore, as the file consists of different variables, I would like to extract one variable at a time into individual files.

回答1:

It's hard to answer this without your specific file. You should look into producing reproducible examples, especially if you're posting to the R board.

For R, check out library(raster) and library(ncdf4). I just grabbed the first grib1 file I saw, and put together a quick example.

library(raster)
library(ncdf4)

download.file(url = 'ftp://ftp.hpc.ncep.noaa.gov/grib/20130815/p06m_2013081500f030.grb', destfile = 'test.grb')

(r <- raster('test.grb'))

n <- writeRaster(r, filename = 'netcdf_in_youR_comp.nc', overwrite = TRUE)

回答2:

I know you ask for a solution using R, but it is much more straightforward to perform this task from the command line with cdo:

cdo -f nc copy test.grb test.nc 

That's all you need to do. Use "-f nc4" if you want netcdf4 conventions.

To extract a variable you can first see what the variable names are using

ncdump -h test.nc

then, once you know the name of the variable you want to extract to a separate file, you can use

cdo selvar,varname test.nc var.nc 

回答3:

you can use ncl installed on you computer

library(ncdf)
 system(ncl_convert2nc  xxxx.grb, internal = TRUE)
 my.nc <- open.ncdf("result.nc")
 print(my.nc)

来源：https://stackoverflow.com/questions/18501257/how-to-convert-grib1-to-netcdf-using-r