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Hi John, Yes, you can get the current length of the frtime dimension by first finding out the dimension ID of the unlimited dimension (using an NF90_INQUIRE function call), then using NF90_INQUIRE_DIMENSION to get the length. You should not have to allocate enough memory to read all of a variable into memory at once. If you dimension your program variables large enough to hold just one time slice of data, then you can just read one time slice (also called a "record") at a time, using the NF90_GET_VAR function, specifying a START argument and a COUNT argument. There is an example that uses the unlimited dimension and reads a record at a time in the file examples/F90/pres_temp_4D_rd.f90 in the netCDF distribution. You can also see it online here: http://www.unidata.ucar.edu/software/netcdf/examples/programs/pres_temp_4D_rd.f90 For a 1D variable, to read the Nth record you would specify START = (/ N /) COUNT = (/ 1 /) For a 2D variable dimensioned in the netCDF file as float var(frtime, gates); if you want to read the Nth record into a Fortran-90 variable declared REAL VAR(GATES) for example, use: START = (/ 1, N /) ! start at the first gate of the Nth record COUNT = (/ GATES, 1 /) ! get GATES values along the gates dimension, ! but only 1 frtime (record) value --Russ Russ Rew UCAR Unidata Program address@hidden http://www.unidata.ucar.edu Ticket Details =================== Ticket ID: AQT-176214 Department: Support netCDF Priority: Normal Status: Closed