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! This is part of the netCDF package.
! Copyright 2006 University Corporation for Atmospheric Research/Unidata.
! See COPYRIGHT file for conditions of use.
! This example writes some surface pressure and temperatures. It is
! intended to illustrate the use of the netCDF fortran 90 API. The
! companion program nc4_sfc_pres_temp_rd.f90 shows how to read the netCDF
! data file created by this program.
! This program is part of the netCDF tutorial:
! http://www.unidata.ucar.edu/software/netcdf/docs/netcdf-tutorial
! Full documentation of the netCDF Fortran 90 API can be found at:
! http://www.unidata.ucar.edu/software/netcdf/docs/netcdf-f90
! $Id: nc4_sfc_pres_temp_wr.f90,v 1.12 2010/04/06 19:32:09 ed Exp $
program nc4_sfc_pres_temp_wr
use netcdf
implicit none
! This is the name of the data file we will create.
character (len = *), parameter :: FILE_NAME = "nc4_sfc_pres_temp.nc"
integer :: ncid
! We are writing 2D data, a 12 x 6 lon-lat grid. We will need two
! netCDF dimensions.
integer, parameter :: NDIMS = 2
integer, parameter :: NLATS = 6, NLONS = 12
character (len = *), parameter :: LAT_NAME = "latitude"
character (len = *), parameter :: LON_NAME = "longitude"
integer :: lat_dimid, lon_dimid
! In addition to the latitude and longitude dimensions, we will also
! create latitude and longitude netCDF variables which will hold the
! actual latitudes and longitudes. Since they hold data about the
! coordinate system, the netCDF term for these is: "coordinate
! variables."
real :: lats(NLATS), lons(NLONS)
integer :: lat_varid, lon_varid
real, parameter :: START_LAT = 25.0, START_LON = -125.0
! We will write surface temperature and pressure fields.
character (len = *), parameter :: PRES_NAME="pressure"
character (len = *), parameter :: TEMP_NAME="temperature"
integer :: pres_varid, temp_varid
integer :: dimids(NDIMS)
! It's good practice for each variable to carry a "units" attribute.
character (len = *), parameter :: UNITS = "units"
character (len = *), parameter :: PRES_UNITS = "hPa"
character (len = *), parameter :: TEMP_UNITS = "celsius"
character (len = *), parameter :: LAT_UNITS = "degrees_north"
character (len = *), parameter :: LON_UNITS = "degrees_east"
! We will create some pressure and temperature data to write out.
real, dimension(:,:), allocatable :: temp_out
real, dimension(:,:), allocatable :: pres_out
real, parameter :: SAMPLE_PRESSURE = 900.0
real, parameter :: SAMPLE_TEMP = 9.0
! Loop indices
integer :: lat, lon
! Allocate memory.
allocate(pres_out(NLONS, NLATS))
allocate(temp_out(NLONS, NLATS))
! Create pretend data. If this were not an example program, we would
! have some real data to write, for example, model output.
do lat = 1, NLATS
lats(lat) = START_LAT + (lat - 1) * 5.0
end do
do lon = 1, NLONS
lons(lon) = START_LON + (lon - 1) * 5.0
end do
do lon = 1, NLONS
do lat = 1, NLATS
pres_out(lon, lat) = SAMPLE_PRESSURE + (lon - 1) * NLATS + (lat - 1)
temp_out(lon, lat) = SAMPLE_TEMP + .25 * ((lon - 1) * NLATS + (lat - 1))
end do
end do
! Create the file.
call check( nf90_create(FILE_NAME, nf90_netcdf4, ncid) )
! Define the dimensions.
call check( nf90_def_dim(ncid, LAT_NAME, NLATS, lat_dimid) )
call check( nf90_def_dim(ncid, LON_NAME, NLONS, lon_dimid) )
! Define the coordinate variables. They will hold the coordinate
! information, that is, the latitudes and longitudes. A varid is
! returned for each.
call check( nf90_def_var(ncid, LAT_NAME, NF90_REAL, lat_dimid, lat_varid) )
call check( nf90_def_var(ncid, LON_NAME, NF90_REAL, lon_dimid, lon_varid) )
! Assign units attributes to coordinate var data. This attaches a
! text attribute to each of the coordinate variables, containing the
! units.
call check( nf90_put_att(ncid, lat_varid, UNITS, LAT_UNITS) )
call check( nf90_put_att(ncid, lon_varid, UNITS, LON_UNITS) )
! Define the netCDF variables. The dimids array is used to pass the
! dimids of the dimensions of the netCDF variables.
dimids = (/ lon_dimid, lat_dimid /)
call check( nf90_def_var(ncid, PRES_NAME, NF90_REAL, dimids, pres_varid) )
call check( nf90_def_var(ncid, TEMP_NAME, NF90_REAL, dimids, temp_varid) )
! Assign units attributes to the pressure and temperature netCDF
! variables.
call check( nf90_put_att(ncid, pres_varid, UNITS, PRES_UNITS) )
call check( nf90_put_att(ncid, temp_varid, UNITS, TEMP_UNITS) )
! End define mode.
call check( nf90_enddef(ncid) )
! Write the coordinate variable data. This will put the latitudes
! and longitudes of our data grid into the netCDF file.
call check( nf90_put_var(ncid, lat_varid, lats) )
call check( nf90_put_var(ncid, lon_varid, lons) )
! Write the pretend data. This will write our surface pressure and
! surface temperature data. The arrays of data are the same size as
! the netCDF variables we have defined.
call check( nf90_put_var(ncid, pres_varid, pres_out) )
call check( nf90_put_var(ncid, temp_varid, temp_out) )
! Close the file.
call check( nf90_close(ncid) )
! If we got this far, everything worked as expected. Yipee!
print *,"*** SUCCESS writing example file nc4_sfc_pres_temp.nc!"
contains
subroutine check(status)
integer, intent ( in) :: status
if(status /= nf90_noerr) then
print *, trim(nf90_strerror(status))
stop 2
end if
end subroutine check
end program nc4_sfc_pres_temp_wr
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