subroutine globalaverage2d(ngrid,var,globaverage2d)

      use comgeomfi_h    
      use geometry_mod, only: cell_area
      implicit none

!==================================================================
!     Purpose
!     -------
!  
!     Inputs
!     ------ 
!     ngrid                 Number of vertical columns
!
!     Authors
!     ------- 
!     Tanguy Bertrand 2015
!     
!==================================================================

#include "dimensions.h"

!-----------------------------------------------------------------------
!     Arguments
      INTEGER ngrid
      REAL var(ngrid)

      ! LOCAL VARIABLES
      INTEGER ig

      ! OUTPUT
      REAL globaverage2d
!-----------------------------------------------------------------------

      globaverage2d = 0.d0
      DO ig=2,ngrid-1
           globaverage2d = globaverage2d + var(ig)*cell_area(ig)
      END DO
      globaverage2d = globaverage2d + var(1)*cell_area(1)*iim
      globaverage2d = globaverage2d + var(ngrid)*cell_area(ngrid)*iim
      globaverage2d = globaverage2d/(totarea+(cell_area(1)+cell_area(ngrid))*(iim-1))

      end subroutine globalaverage2d