SUBROUTINE read_map2D(filename, varname, timestep, inverse, varout)
  ! Open file and read one variable for one timestep.
  ! Return variable for the given timestep.
  USE dimphy
  USE netcdf, ONLY: nf90_open, nf90_close, nf90_nowrite, nf90_noerr, nf90_get_var, nf90_inq_varid
  USE lmdz_grid_phy
  USE lmdz_phys_para
  USE lmdz_print_control, ONLY: lunout

  IMPLICIT NONE

  ! Input arguments
  CHARACTER(len = *), INTENT(IN) :: filename     ! name of file to read
  CHARACTER(len = *), INTENT(IN) :: varname      ! name of variable in file
  INTEGER, INTENT(IN) :: timestep     ! actual timestep
  LOGICAL, INTENT(IN) :: inverse      ! TRUE if latitude needs to be inversed
  ! Output argument
  REAL, DIMENSION(klon), INTENT(OUT) :: varout  ! The variable read from file for the given timestep

  ! Local variables
  INTEGER :: j
  INTEGER :: nid, nvarid, ierr
  INTEGER, DIMENSION(3) :: start, count
  CHARACTER(len = 20) :: modname = 'read_map2D'

  REAL, DIMENSION(nbp_lon, nbp_lat) :: var_glo2D     ! 2D global
  REAL, DIMENSION(nbp_lon, nbp_lat) :: var_glo2D_tmp ! 2D global
  REAL, DIMENSION(klon_glo) :: var_glo1D     ! 1D global

  ! Read variable from file. Done by master process MPI and master thread OpenMP
  IF (is_mpi_root .AND. is_omp_root) THEN
    ierr = nf90_open(trim(filename), nf90_nowrite, nid)
    IF (ierr /= nf90_noerr) CALL write_err_mess('Problem in opening file')

    ierr = nf90_inq_varid(nid, trim(varname), nvarid)
    IF (ierr /= nf90_noerr) CALL write_err_mess('The variable is absent in file')

    start = (/1, 1, timestep/)
    count = (/nbp_lon, nbp_lat, 1/)
    ierr = nf90_get_var(nid, nvarid, var_glo2D, start, count)
    IF (ierr /= nf90_noerr) CALL write_err_mess('Problem in reading varaiable')

    ierr = nf90_close(nid)
    IF (ierr /= nf90_noerr) CALL write_err_mess('Problem in closing file')

    ! Inverse latitude order
    IF (inverse) THEN
      var_glo2D_tmp(:, :) = var_glo2D(:, :)
      DO j = 1, nbp_lat
        var_glo2D(:, j) = var_glo2D_tmp(:, nbp_lat - j + 1)
      END DO
    END IF

    ! Transform the global field from 2D to 1D
    CALL grid2Dto1D_glo(var_glo2D, var_glo1D)

    WRITE(lunout, *) 'in read_map2D, filename = ', trim(filename)
    WRITE(lunout, *) 'in read_map2D, varname  = ', trim(varname)
    WRITE(lunout, *) 'in read_map2D, timestep = ', timestep
  ENDIF

  ! Scatter gloabl 1D variable to all processes
  CALL scatter(var_glo1D, varout)

CONTAINS
  SUBROUTINE write_err_mess(err_mess)
    USE lmdz_print_control, ONLY: lunout
    USE lmdz_abort_physic, ONLY: abort_physic
    IMPLICIT NONE
    CHARACTER(len = *), INTENT(IN) :: err_mess

    WRITE(lunout, *) 'Error in read_map2D, filename = ', trim(filename)
    WRITE(lunout, *) 'Error in read_map2D, varname  = ', trim(varname)
    WRITE(lunout, *) 'Error in read_map2D, timestep = ', timestep

    CALL abort_physic(modname, err_mess, 1)

  END SUBROUTINE write_err_mess

END SUBROUTINE read_map2D