This archive contains answers to questions sent to Unidata support through mid-2025. Note that the archive is no longer being updated. We provide the archive for reference; many of the answers presented here remain technically correct, even if somewhat outdated. For the most up-to-date information on the use of NSF Unidata software and data services, please consult the Software Documentation first.
> Organization: NCAR/ACD > Keywords: 199405122005.AA14988 Hi Wanli, > I am a new user to netCDF. I need to download a lot of > datasets in netCDF on IBM RS6000 > (AIX3.2) for my FORTRAN program. > Now I have installed netCDF package on the workstation(AIX3.2) > followed README > > export CFLAGS="" > export FC=xlf > configure --prefix=/scratch/wanliwu/nmcdata > make "all" > make "test" > make "install" > make "clean" > > It seems so far so good for the installation. > > Is the netCDF ready for me? if not, what else should I do? go to > fortran directory to do some > similiar make again? > if it is ready , how can I do in my FORTRAN program to connect to the > dataset, say I get a dataset in netCDF -- hgt85.nc ? What I want is > tranfor the netCDF data to FORTRAN data so that my numerical model can read > it ? Your FORTRAN program has to make calls to the netCDF library subroutines to open the netCDF file and read data from the file into FORTRAN arrays. To read the data, you will need to know the names of the variables in the netCDF dataset. For this purpose, the "ncdump" program is useful. For example, % ncdump -c hgt85.nc will tell you the names and shapes of variables in the file, as well as their attributes and coordinate values. This is all documented in the netCDF User's Guide, which is part of the software distribution but also available online using Mosaic at http://www.unidata.ucar.edu/packages/netcdf/ To open the file in a FORTRAN program, look at the netCDF User's Guide to see how to call the NCOPN subroutine. For example: INCLUDE 'netcdf.inc' ... INTEGER NCID, RCODE ... NCID = NCOPN('hgt85.nc.nc', NCNOWRIT, RCODE) To get data from a netCDF variable named "Z" into your FORTRAN array named "RH", for example, read the netCDF User's Guide to learn how to use the NCVID and NCVGT subroutines: PARAMETER (NDIMS=3) ! number of dimensions PARAMETER (TIMES=3, LATS=5, LONS=10) ! dimension sizes INTEGER NCID, RCODE INTEGER ZID ! variable ID INTEGER START(NDIMS), COUNT(NDIMS) ! hyperslab DOUBLE RH(LONS, LATS, TIMES) DATA START /1, 1, 1/ ! start at first value DATA COUNT /LONS, LATS, TIMES/ ! how many values in each dimension ... ZID = NCVID (NCID, 'Z', RCODE) ! get ID CALL NCVGT (NCID, ZID, START, COUNT, RH, RCODE) ! read the values This is just an example. You will need to read the documentation to use the netCDF library. Also, questions about the netCDF library should be sent to "address@hidden" so that they will be directed to the right person to answer the question. __________________________________________________________________________ Russ Rew UCAR Unidata Program address@hidden P.O. Box 3000 (303)497-8645 Boulder, Colorado 80307-3000