                     module diag_integral_mod
#include <fms_platform.h>
! <CONTACT EMAIL="Fei.Liu@noaa.gov">
!  fil
! </CONTACT>
! <REVIEWER EMAIL="">
! </REVIEWER>
! <HISTORY SRC="http://www.gfdl.noaa.gov/fms-cgi-bin/cvsweb.cgi/FMS/"/>
! <OVERVIEW>
!    diag_integral_mod computes and outputs global and / or 
!    hemispheric physics integrals.
! </OVERVIEW>
! <DESCRIPTION>
! </DESCRIPTION>

!  shared modules:

use time_manager_mod, only:  time_type, get_time, set_time,  &
                             time_manager_init, &
                             operator(+),  operator(-),      &
                             operator(==), operator(>=),     &
                             operator(/=)
use mpp_mod,          only:  input_nml_file
use fms_mod,          only:  open_file, file_exist, error_mesg, &
                             open_namelist_file, check_nml_error, &
                             fms_init, &
                             mpp_pe, mpp_root_pe,&
                             FATAL, write_version_number, &
                             stdlog, close_file
use constants_mod,    only:  radius, constants_init
use mpp_mod,          only:  mpp_sum, mpp_init

!--------------------------------------------------------------------

implicit none
private

!----------------------------------------------------------------------
!    diag_integral_mod computes and outputs global and / or 
!    hemispheric physics integrals.
!----------------------------------------------------------------------

!---------------------------------------------------------------------
!----------- version number for this module -------------------

character(len=128) :: version = '$Id: diag_integral.F90,v 21.0 2014/12/15 21:42:14 fms Exp $'
character(len=128) :: tagname = '$Name: ulm $'


!---------------------------------------------------------------------
!------ interfaces ------

public      &
          diag_integral_init, diag_integral_field_init, &
          sum_diag_integral_field, diag_integral_output,  &
          diag_integral_end  

interface sum_diag_integral_field
   module procedure sum_field_2d,   &
                    sum_field_2d_hemi, &
                    sum_field_3d,   &
                    sum_field_wght_3d
end interface

private         &

!   from diag_integral_init:
          set_axis_time,  &

!   from diag_integral_field_init and sum_diag_integral_field:
          get_field_index, &

!   from diag_integral_output and diag_integral_end:
          write_field_averages,  &           

!   from write_field_averages:
          format_text_init, format_data_init, &
          get_axis_time,     &

!   from diag_integral_output:
          diag_integral_alarm, &

!   from sum_diag_integral_field:
          vert_diag_integral

!---------------------------------------------------------------------
!------ namelist -------

integer, parameter  ::    &
                      mxch = 64    ! maximum number of characters in 
                                   ! the optional output file name
real                ::    &
         output_interval = -1.0    ! time interval at which integrals
                                   ! are to be output
character(len=8)    ::    &
            time_units = 'hours'   ! time units associated with
                                   ! output_interval
character(len=mxch) ::    &
                 file_name = ' '   ! optional integrals output file name
logical             ::    &
           print_header = .true.   ! print a header for the integrals
                                   ! file ?
integer             ::    &
       fields_per_print_line = 4   ! number of fields to write per line
                                   ! of output


namelist / diag_integral_nml /      &
                                output_interval, time_units,  &
                                file_name, print_header, &
                                fields_per_print_line

!---------------------------------------------------------------------
!------- public data ------


!---------------------------------------------------------------------
!------- private data ------

!---------------------------------------------------------------------
!    variables associated with the determination of when integrals
!    are to be written.
!         Next_alarm_time  next time at which integrals are to be 
!                          written   
!         Alarm_interval   time interval between writing integrals
!         Zero_time        time_type variable set to (0,0); used as
!                          flag to indicate integrals are not being
!                          output
!         Time_init_save   initial time associated with experiment;
!                          used as a base for defining time
!---------------------------------------------------------------------
type (time_type) :: Next_alarm_time, Alarm_interval, Zero_time
type (time_type) :: Time_init_save

!---------------------------------------------------------------------
!    variables used in determining weights associated with each
!    contribution to the integrand.
!        area         area of each grid box
!        idim         x dimension of grid on local processor
!        jdim         y dimension of grid on local processor
!        field_size   number of columns on global domain
!        sum_area     surface area of globe
!---------------------------------------------------------------------
real, allocatable, dimension(:,:) :: area
integer                           :: idim, jdim, field_size
real                              :: sum_area

!---------------------------------------------------------------------
!    variables used to define the integral fields: 
!      max_len_name     maximum length of name associated with integral
!      max_num_field    maximum number of integrals allowed
!      num_field        number of integrals that have been activated
!      field_name(i)    name associated with integral i
!      field_format(i)  output format for integral i
!      field_sum(i)     integrand for integral i
!      field_count(i)   number of values in integrand i
!---------------------------------------------------------------------
integer, parameter          :: max_len_name   = 12
integer, parameter          :: max_num_field = 32    
integer                     :: num_field = 0
character(len=max_len_name) :: field_name   (max_num_field)
character(len=16)           :: field_format (max_num_field)
real                        :: field_sum    (max_num_field)
integer                     :: field_count  (max_num_field)

!---------------------------------------------------------------------
!    variables defining output formats.
!       format_text       format statement for header
!       format_data       format statement for data output
!       do_format_data    a data format needs to be generated ? 
!       nd                number of characters in data format statement
!       nt                number of characters in text format statement
!---------------------------------------------------------------------
character(len=160) :: format_text, format_data
logical            :: do_format_data = .true.
integer            :: nd, nt

!--------------------------------------------------------------------
!    miscellaneous variables.
!---------------------------------------------------------------------
integer :: diag_unit = 0             ! unit number for output file
logical :: module_is_initialized = .false.  
                                     ! module is initialized ?


!-----------------------------------------------------------------------
!-----------------------------------------------------------------------



                           contains



!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
!
!                     PUBLIC SUBROUTINES
!
!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

!####################################################################
! <SUBROUTINE NAME="diag_integral_init">
!  <OVERVIEW>
!    diag_integral_init is the constructor for diag_integral_mod.
!  </OVERVIEW>
!  <DESCRIPTION>
!    diag_integral_init is the constructor for diag_integral_mod.
!  </DESCRIPTION>
!  <TEMPLATE>
!   call diag_integral_init (Time_init, Time, blon, blat)
!  </TEMPLATE>
!  <IN NAME="Time_init" TYPE="time_type">
!   Initial time to start the integral
!  </IN>
!  <IN NAME="Time" TYPE="time_type">
!   current time
!  </IN>
!  <IN NAME="latb" TYPE="real">
!   array of model latitudes at cell boundaries [radians]
!  </IN>
!  <IN NAME="lonb" TYPE="real">
!   array of model longitudes at cell boundaries [radians]
!  </IN>
! </SUBROUTINE>
!
subroutine diag_integral_init (Time_init, Time, blon, blat, area_in)

!--------------------------------------------------------------------
!    diag_integral_init is the constructor for diag_integral_mod.
!--------------------------------------------------------------------

type (time_type),  intent(in), optional :: Time_init, Time
real,dimension(:,:), intent(in), optional :: blon, blat, area_in
      
!--------------------------------------------------------------------
!  intent(in),optional variables:
!
!     Time_init
!     Time
!     blon
!     blat
!
!---------------------------------------------------------------------

!---------------------------------------------------------------------
!  local variables:

      real    :: rsize
      integer :: unit, io, ierr, nc, logunit
      integer :: field_size_local
      real    :: sum_area_local

!---------------------------------------------------------------------
!  local variables:
!
!       r2
!       rsize
!       unit
!       io
!       ierr
!       seconds
!       nc
!       i,j
!   
!--------------------------------------------------------------------

!---------------------------------------------------------------------
!    if routine has already been executed, exit.
!---------------------------------------------------------------------
      if (module_is_initialized) return
 
!---------------------------------------------------------------------
!    verify that modules used by this module that are not called later
!    have already been initialized.
!---------------------------------------------------------------------
      call fms_init
      call mpp_init
      call constants_init
      call time_manager_init 

!----------------------------------------------------------------------
!    if this is the initialization call, proceed. if this was simply
!    a verification of previous initialization, return.
!--------------------------------------------------------------------
      if (present(Time_init) .and. present(Time) .and. &
          present(blon) .and. present(blat) ) then

!-----------------------------------------------------------------------
!    read namelist.
!-----------------------------------------------------------------------
      if ( file_exist('input.nml')) then
#ifdef INTERNAL_FILE_NML
        read (input_nml_file, nml=diag_integral_nml, iostat=io)
        ierr = check_nml_error(io,'diag_integral_nml')
#else   
        unit =  open_namelist_file ( )
        ierr=1; do while (ierr /= 0)
        read  (unit, nml=diag_integral_nml, iostat=io, end=10)
        ierr = check_nml_error(io,'diag_integral_nml')
        end do
10      call close_file (unit)
#endif
      endif
 
!---------------------------------------------------------------------
!    write version number and namelist to logfile.
!---------------------------------------------------------------------
      call write_version_number (version, tagname)
      logunit = stdlog()
      if (mpp_pe() == mpp_root_pe() ) &
                       write (logunit, nml=diag_integral_nml)

!--------------------------------------------------------------------
!    save the initial time to time-stamp the integrals which will be
!    calculated.
!---------------------------------------------------------------------
      Time_init_save = Time_init

!---------------------------------------------------------------------
!    define the model grid sizes and the total number of columns on
!    the processor. sum over all processors and store the global
!    number of columns in field_size.
!---------------------------------------------------------------------
      idim = size(blon,1) - 1
      jdim = size(blon,2) - 1
      field_size_local = idim*jdim
      rsize = real(field_size_local)
      call mpp_sum (rsize)
      field_size = nint(rsize)

!---------------------------------------------------------------------
!    define an array to hold the surface area of each grid column 
!    so that the integrals may be weighted properly. sum over the 
!    processor, and then over all processors, storing the total
!    global surface area in sum_area.
!---------------------------------------------------------------------
      allocate (area(idim,jdim))

      area = area_in

      sum_area_local = sum(area)
      sum_area = sum_area_local
      call mpp_sum (sum_area)

!--------------------------------------------------------------------
!    if integral output is  to go to a file, open the file on unit
!    diag_unit.
!--------------------------------------------------------------------
      if (file_name(1:1) /= ' ' ) then
        nc = len_trim(file_name)
        diag_unit = open_file (file_name(1:nc), action='write')
      endif

!---------------------------------------------------------------------
!    define the variables needed to control the time interval of
!    output. Zero time is a flag indicating that the alarm is not set,
!    i.e., integrals are not desired.  otherwise set the next time to
!    output integrals to be at the value of nml variable
!    output_interval from now.
!---------------------------------------------------------------------
      Zero_time = set_time (0,0)
      if (output_interval >= -0.01) then
        Alarm_interval = set_axis_time (output_interval, time_units)
        Next_alarm_time = Time + Alarm_interval
      else
        Alarm_interval = Zero_time
      endif
      Next_alarm_time = Time + Alarm_interval

!--------------------------------------------------------------------
!    deallocate the local array and mark the module as initialized.
!--------------------------------------------------------------------
      module_is_initialized = .true.
   endif  ! (present optional arguments)

!-----------------------------------------------------------------------


end subroutine diag_integral_init



!######################################################################
! <SUBROUTINE NAME="diag_integral_field_init">
!  <OVERVIEW>
!    diag_integral_field_init registers and intializes an integral field
!  </OVERVIEW>
!  <DESCRIPTION>
!    diag_integral_field_init registers and intializes an integral field
!  </DESCRIPTION>
!  <TEMPLATE>
!   call diag_integral_field_init (name, format)
!  </TEMPLATE>
!  <IN NAME="name" TYPE="character">
!   Name of the field to be integrated
!  </IN>
!  <IN NAME="format" TYPE="character">
!   Output format of the field to be integrated
!  </IN>
! </SUBROUTINE>
!
 subroutine diag_integral_field_init (name, format)

!---------------------------------------------------------------------
!
!---------------------------------------------------------------------

character(len=*), intent(in) :: name, format

!---------------------------------------------------------------------
!   intent(in) variables:
!
!       name
!       format
!
!---------------------------------------------------------------------

!---------------------------------------------------------------------
!  local variables:
 
      integer :: field   ! index assigned to the current integral

!----------------------------------------------------------------------

!----------------------------------------------------------------------
!    note: no initialization is required for this interface. all needed
!    variables are initialized in the source.
!---------------------------------------------------------------------

!--------------------------------------------------------------------
!    make sure the integral name is not too long.
!--------------------------------------------------------------------
      if (len(name) > max_len_name )  then
        call error_mesg ('diag_integral_mod',  &
                ' integral name too long', FATAL)
      endif

!---------------------------------------------------------------------
!    check to be sure the integral name has not already been 
!    initialized.
!---------------------------------------------------------------------
      field = get_field_index (name)
      if (field /= 0)   then
        call error_mesg ('diag_integral_mod', &
                             'integral name already exists', FATAL)
      endif

!-------------------------------------------------------------------
!    prepare to register the integral. make sure that there are not
!    more integrals registered than space was provided for; if so, exit.
!----------------------------------------------------------------------
      num_field = num_field + 1
      if (num_field > max_num_field)  then
        call error_mesg ('diag_integral_mod', &
                              'too many fields initialized', FATAL)
      endif

!--------------------------------------------------------------------
!    register the name and output format desired for the given integral.
!    initialize its value and the number of grid points that have been
!    counted to zero.
!--------------------------------------------------------------------
      field_name   (num_field) = name
      field_format (num_field) = format
      field_sum    (num_field) = 0.0
      field_count  (num_field) = 0

!----------------------------------------------------------------------


end subroutine diag_integral_field_init


!#####################################################################

!
!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
!
!                  INTERFACE SUM_DIAG_INTEGRAL_FIELD
!
!  call sum_diag_integral_field (name, data, is, js) 
!     or
!  call sum_diag_integral_field (name, data, wt, is, js) 
!     or
!  call sum_diag_integral_field (name, data, is, ie, js, je) 
!
!  in the first option data may be either
!     real,              intent(in) :: data(:,:)  [ sum_field_2d ]
!  or
!     real,              intent(in) :: data(:,:,:) [ sum_field_3d ]
!
!-------------------------------------------------------------------
! intent(in) arguments:
!
!  character(len=*),  intent(in) :: name
!  real,              intent(in) :: wt(:,:,:)
!  integer, optional, intent(in) :: is, ie, js, je
!
!--------------------------------------------------------------------
! intent(in) arguments:
!
!     name         name associated with integral
!     data         field of integrands to be summed over
!     wt           vertical weighting factor to be applied to integrands
!                  when summing
!     is,ie,js,je  starting/ending i,j indices over which summation is 
!                  to occur
!
!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

!#####################################################################
! <SUBROUTINE NAME="sum_field_2d">
!  <OVERVIEW>
!    Perform a 2 dimensional summation of named field
!  </OVERVIEW>
!  <DESCRIPTION>
!    Perform a 2 dimensional summation of named field
!  </DESCRIPTION>
!  <TEMPLATE>
!   call sum_field_2d (name, data, is, js)
!  </TEMPLATE>
!  <IN NAME="name" TYPE="character">
!   Name of the field to be integrated
!  </IN>
!  <IN NAME="data" TYPE="real">
!   field of integrands to be summed over
!  </IN>
!  <IN NAME="is, js" TYPE="integer">
!   starting i,j indices over which summation is 
!                  to occur
!  </IN>
! </SUBROUTINE>
!
subroutine sum_field_2d (name, data, is, js)

character(len=*),  intent(in) :: name
real,              intent(in) :: data(:,:)
integer, optional, intent(in) :: is, js

!---------------------------------------------------------------------
! local variables:

      integer :: field           ! index of desired integral
      integer :: i1, j1, i2, j2  ! location indices of current data in 
                                 ! processor-global coordinates

!----------------------------------------------------------------------
!    be sure module has been initialized.
!---------------------------------------------------------------------
      if (.not. module_is_initialized ) then
        call error_mesg ('diag_integral_mod',   &
              'module has not been initialized', FATAL )
      endif

!---------------------------------------------------------------------
!    obtain the index of the current integral. make certain it is valid.
!---------------------------------------------------------------------
      field = get_field_index (name)
      if (field == 0)  then
        call error_mesg ('diag_integral_mod', &
                                    'field does not exist', FATAL)
      endif

!---------------------------------------------------------------------
!   define the processor-global indices of the current data. use the 
!   value 1 for the initial grid points, if is and js are not input.
!---------------------------------------------------------------------
     i1 = 1;  if (present(is)) i1 = is
     j1 = 1;  if (present(js)) j1 = js
     i2 = i1 + size(data,1) - 1
     j2 = j1 + size(data,2) - 1

!---------------------------------------------------------------------
!    increment the count of points toward this integral and add the 
!    values at this set of grid points to the accumulation array.
!---------------------------------------------------------------------
!$OMP CRITICAL
      field_count (field) = field_count(field) +   &
                            size(data,1)*size(data,2)
      field_sum   (field) = field_sum   (field) +  &
                            sum (data * area(i1:i2,j1:j2))

!$OMP END CRITICAL
!--------------------------------------------------------------------

 end subroutine sum_field_2d


!#######################################################################
! <SUBROUTINE NAME="sum_field_3d">
!  <OVERVIEW>
!    Perform a 3 dimensional summation of named field
!  </OVERVIEW>
!  <DESCRIPTION>
!    Perform a 3 dimensional summation of named field
!  </DESCRIPTION>
!  <TEMPLATE>
!   call sum_field_3d (name, data, is, js)
!  </TEMPLATE>
!  <IN NAME="name" TYPE="character">
!   Name of the field to be integrated
!  </IN>
!  <IN NAME="data" TYPE="real">
!   field of integrands to be summed over
!  </IN>
!  <IN NAME="is, js" TYPE="integer">
!   starting i,j indices over which summation is 
!                  to occur
!  </IN>
! </SUBROUTINE>
!
subroutine sum_field_3d (name, data, is, js)

character(len=*),  intent(in) :: name
real,              intent(in) :: data(:,:,:)
integer, optional, intent(in) :: is, js

!---------------------------------------------------------------------
! local variables:

      real, dimension (size(data,1),  &
                       size(data,2)) :: data2

      integer :: field           
      integer :: i1, j1, i2, j2  
                             
!---------------------------------------------------------------------
! local variables:
!
!     data2
!     field           ! index of desired integral
!     i1, j1, i2, j2  ! location indices of current data in 
!                       processor-global coordinates
!
!--------------------------------------------------------------------

!----------------------------------------------------------------------
!    be sure module has been initialized.
!---------------------------------------------------------------------
      if (.not. module_is_initialized ) then
        call error_mesg ('diag_integral_mod',   &
              'module has not been initialized', FATAL )
      endif

!---------------------------------------------------------------------
!    obtain the index of the current integral. make certain it is valid.
!---------------------------------------------------------------------
      field = get_field_index (name)
      if (field == 0)   then
        call error_mesg ('diag_integral_mod', &
                               'field does not exist', FATAL)
      endif

!---------------------------------------------------------------------
!   define the processor-global indices of the current data. use the 
!   value 1 for the initial grid points, if is and js are not input.
!---------------------------------------------------------------------
      i1 = 1;  if (present(is)) i1 = is
      j1 = 1;  if (present(js)) j1 = js
      i2 = i1 + size(data,1) - 1
      j2 = j1 + size(data,2) - 1

!---------------------------------------------------------------------
!    increment the count of points toward this integral. sum first
!    in the vertical and then add the values at this set of grid points 
!    to the accumulation array.
!---------------------------------------------------------------------
!$OMP CRITICAL
      field_count (field) = field_count (field) +   &
                            size(data,1)*size(data,2)
      data2 = sum(data,3)
      field_sum   (field) = field_sum   (field) +  &
                            sum (data2 * area(i1:i2,j1:j2))

!$OMP END CRITICAL
!---------------------------------------------------------------------

end subroutine sum_field_3d


!#######################################################################
! <SUBROUTINE NAME="sum_field_wght_3d">
!  <OVERVIEW>
!    Perform a 3 dimensional weighted summation of named field
!  </OVERVIEW>
!  <DESCRIPTION>
!    Perform a 3 dimensional weighted summation of named field
!  </DESCRIPTION>
!  <TEMPLATE>
!   call sum_field_wght_3d (name, data, wt, is, js)
!  </TEMPLATE>
!  <IN NAME="name" TYPE="character">
!   Name of the field to be integrated
!  </IN>
!  <IN NAME="data" TYPE="real">
!   field of integrands to be summed over
!  </IN>
!  <IN NAME="wt" TYPE="real">
!   the weight function to be evaluated at summation
!  </IN>
!  <IN NAME="is, js" TYPE="integer">
!   starting i,j indices over which summation is 
!                  to occur
!  </IN>
! </SUBROUTINE>
!
subroutine sum_field_wght_3d (name, data, wt, is, js)

character(len=*),  intent(in) :: name
real,              intent(in) :: data(:,:,:), wt(:,:,:)
integer, optional, intent(in) :: is, js

!---------------------------------------------------------------------
! local variables:

      real, dimension (size(data,1),size(data,2)) :: data2
      integer :: field, i1, j1, i2, j2

!---------------------------------------------------------------------
! local variables:
!
!     data2
!     field           ! index of desired integral
!     i1, j1, i2, j2  ! location indices of current data in 
!                       processor-global coordinates
!
!--------------------------------------------------------------------

!----------------------------------------------------------------------
!    be sure module has been initialized.
!---------------------------------------------------------------------
      if (.not. module_is_initialized ) then
        call error_mesg ('diag_integral_mod',   &
              'module has not been initialized', FATAL )
      endif

!---------------------------------------------------------------------
!    obtain the index of the current integral. make certain it is valid.
!---------------------------------------------------------------------
      field = get_field_index (name)
      if (field == 0)   then
        call error_mesg ('diag_integral_mod', &
                               'field does not exist', FATAL)
      endif

!---------------------------------------------------------------------
!   define the processor-global indices of the current data. use the 
!   value 1 for the initial grid points, if is and js are not input.
!---------------------------------------------------------------------
      i1 = 1;  if (present(is)) i1 = is
      j1 = 1;  if (present(js)) j1 = js
      i2 = i1 + size(data,1) - 1
      j2 = j1 + size(data,2) - 1

!---------------------------------------------------------------------
!    increment the count of points toward this integral. sum first
!    in the vertical (including a vertical weighting factor) and then 
!    add the values at this set of grid points to the accumulation 
!    array.
!---------------------------------------------------------------------
!$OMP CRITICAL
      field_count (field) = field_count (field) +   &
                            size(data,1)*size(data,2)
      data2 = vert_diag_integral (data, wt) 
      field_sum(field) = field_sum   (field) +  &
                         sum (data2 * area(i1:i2,j1:j2))

!$OMP END CRITICAL
!----------------------------------------------------------------------


end subroutine sum_field_wght_3d

  
!#######################################################################
! <SUBROUTINE NAME="sum_field_2d_hemi">
!  <OVERVIEW>
!    Perform a 2 dimensional hemispherical summation of named field
!  </OVERVIEW>
!  <DESCRIPTION>
!    Perform a 2 dimensional hemispherical summation of named field
!  </DESCRIPTION>
!  <TEMPLATE>
!   call sum_field_2d_hemi (name, data, is, ie, js, je)
!  </TEMPLATE>
!  <IN NAME="name" TYPE="character">
!   Name of the field to be integrated
!  </IN>
!  <IN NAME="data" TYPE="real">
!   field of integrands to be summed over
!  </IN>
!  <IN NAME="is, js, ie, je" TYPE="integer">
!   starting/ending i,j indices over which summation is 
!                  to occur
!  </IN>
! </SUBROUTINE>
!
subroutine sum_field_2d_hemi (name, data, is, ie, js, je)

character(len=*),  intent(in) :: name
real,              intent(in) :: data(:,:)
integer,           intent(in) :: is, js, ie, je

!---------------------------------------------------------------------
! local variables:
   integer :: field, i1, j1, i2, j2

!---------------------------------------------------------------------
! local variables:
!
!     field           ! index of desired integral
!     i1, j1, i2, j2  ! location indices of current data in 
!                       processor-global coordinates
!
!--------------------------------------------------------------------

!----------------------------------------------------------------------
!    be sure module has been initialized.
!---------------------------------------------------------------------
      if (.not. module_is_initialized ) then
        call error_mesg ('diag_integral_mod',   &
              'module has not been initialized', FATAL )
      endif

!---------------------------------------------------------------------
!    obtain the index of the current integral. make certain it is valid.
!---------------------------------------------------------------------
      field = get_field_index (name)
      if (field == 0)    then
        call error_mesg ('diag_integral_mod', &
                               'field does not exist', FATAL)
      endif

!----------------------------------------------------------------------
!    define the processor-global indices of the current data. this form
!    is needed to handle case of 2d domain decomposition with physics 
!    window smaller than processor domain size.
!----------------------------------------------------------------------
      i1 = mod ( (is-1), size(data,1) ) + 1
      i2 = i1 + size(data,1) - 1

!--------------------------------------------------------------------
!    for a hemispheric sum, sum one jrow at a time in case a processor
!    has data from both hemispheres.
!--------------------------------------------------------------------
      j1 = mod ( (js-1) ,size(data,2) ) + 1
      j2 = j1

!----------------------------------------------------------------------
!    increment the count of points toward this integral. include hemi-
!    spheric factor of 2 in field_count. add the data values at this 
!    set of grid points to the accumulation array.
!----------------------------------------------------------------------
!$OMP CRITICAL
      field_count (field) = field_count (field) + 2* (i2-i1+1)*(j2-j1+1)
      field_sum   (field) = field_sum   (field) +  &
                            sum (data(i1:i2,j1:j2)*area(is:ie,js:je))

!$OMP END CRITICAL
!---------------------------------------------------------------------


 end subroutine sum_field_2d_hemi



!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
!
!                  END INTERFACE SUM_DIAG_INTEGRAL_FIELD
!
!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


!##################################################################
! <SUBROUTINE NAME="diag_integral_output">
!  <OVERVIEW>
!    diag_integral_output determines if this is a timestep on which
!    integrals are to be written. if not, it returns; if so, it calls
!    write_field_averages.
!  </OVERVIEW>
!  <DESCRIPTION>
!    diag_integral_output determines if this is a timestep on which
!    integrals are to be written. if not, it returns; if so, it calls
!    write_field_averages.
!  </DESCRIPTION>
!  <TEMPLATE>
!   call diag_integral_output (Time)
!  </TEMPLATE>
!  <IN NAME="Time" TYPE="time_type">
!   integral time stamp at the current time 
!  </IN>
! </SUBROUTINE>
!
subroutine diag_integral_output (Time)

!---------------------------------------------------------------------
!    diag_integral_output determines if this is a timestep on which
!    integrals are to be written. if not, it returns; if so, it calls
!    write_field_averages.
!---------------------------------------------------------------------

type (time_type), intent(in) :: Time

!-----------------------------------------------------------------------
!  intent(in) variables:
!
!         Time     integral time stamp at the current time 
!                  [ time_type ]
!
!---------------------------------------------------------------------

!----------------------------------------------------------------------
!    be sure module has been initialized.
!---------------------------------------------------------------------
      if (.not. module_is_initialized ) then
        call error_mesg ('diag_integral_mod',   &
              'module has not been initialized', FATAL )
      endif

!---------------------------------------------------------------------
!    see if integral output is desired at this time. 
!---------------------------------------------------------------------
      if ( diag_integral_alarm(Time) ) then   

!---------------------------------------------------------------------
!    write the integrals by calling write_field_averages. upon return 
!    reset the alarm to the next diagnostics time.
!---------------------------------------------------------------------
        call write_field_averages (Time)
        Next_alarm_time = Next_alarm_time + Alarm_interval
      endif

!-----------------------------------------------------------------------


end subroutine diag_integral_output


!#######################################################################
! <SUBROUTINE NAME="diag_integral_end">
!  <OVERVIEW>
!    diag_integral_end is the destructor for diag_integral_mod.
!  </OVERVIEW>
!  <DESCRIPTION>
!    diag_integral_end is the destructor for diag_integral_mod.
!  </DESCRIPTION>
!  <TEMPLATE>
!   call diag_integral_end (Time)
!  </TEMPLATE>
!  <IN NAME="Time" TYPE="time_type">
!   integral time stamp at the current time 
!  </IN>
! </SUBROUTINE>
!
subroutine diag_integral_end (Time)

!--------------------------------------------------------------------
!    diag_integral_end is the destructor for diag_integral_mod.
!--------------------------------------------------------------------

type (time_type), intent(in) :: Time

!----------------------------------------------------------------------
!    be sure module has been initialized.
!---------------------------------------------------------------------
      if (.not. module_is_initialized ) then
        call error_mesg ('diag_integral_mod',   &
              'module has not been initialized', FATAL )
      endif

!---------------------------------------------------------------------
!    if the alarm interval was set to Zero_time (meaning no integral 
!    output during the model run) call write_field_averages to output
!    the integrals valid over the entire period of integration. 
!---------------------------------------------------------------------
      if (Alarm_interval == Zero_time ) then  
!       if (Alarm_interval /= Zero_time ) then  
!       else
        call write_field_averages (Time)
      endif

!---------------------------------------------------------------------
!    deallocate module variables.
!---------------------------------------------------------------------
      deallocate (area)

!---------------------------------------------------------------------
!    mark the module as uninitialized.
!---------------------------------------------------------------------
      module_is_initialized = .false.

!--------------------------------------------------------------------

end subroutine diag_integral_end




!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
!                                
!                    PRIVATE SUBROUTINES
!                                
!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%




!#######################################################################
! <FUNCTION NAME="set_axis_time">
!  <OVERVIEW>
!    Function to convert input time to a time_type
!  </OVERVIEW>
!  <DESCRIPTION>
!    Function to convert input time to a time_type
!  </DESCRIPTION>
!  <TEMPLATE>
!   time = set_axis_time (atime, units)
!  </TEMPLATE>
!  <IN NAME="atime" TYPE="real">
!   integral time stamp at the current time 
!  </IN>
!  <IN NAME="units" TYPE="character">
!   input units, not used
!  </IN>
! </FUNCTION>
!
function set_axis_time (atime, units) result (Time)

!--------------------------------------------------------------------
!
!--------------------------------------------------------------------

real,             intent(in) :: atime
character(len=*), intent(in) :: units
type(time_type)  :: Time

!---------------------------------------------------------------------
!  intent(in) variables:
!
!       atime
!       units
!
!  result:
!
!       Time
!
!--------------------------------------------------------------------

!---------------------------------------------------------------------
!  local variables:

      integer          :: sec     ! seconds corresponding to the input
                                  ! variable atime
      integer          :: day = 0 ! day component of time_type variable

!--------------------------------------------------------------------
!    convert the input time to seconds, regardless of input units.
!--------------------------------------------------------------------
      if (units(1:3) == 'sec') then
         sec = int(atime + 0.5)
      else if (units(1:3) == 'min') then
         sec = int(atime*60. + 0.5)
      else if (units(1:3) == 'hou') then
         sec = int(atime*3600. + 0.5)
      else if (units(1:3) == 'day') then
         sec = int(atime*86400. + 0.5)
      else
         call error_mesg('diag_integral_mod', &
                         'Invalid units sent to set_axis_time', FATAL)
      endif

!--------------------------------------------------------------------
!    convert the time in seconds to a time_type variable.
!--------------------------------------------------------------------
      Time = set_time (sec, day)


end function set_axis_time

!######################################################################
! <FUNCTION NAME="get_field_index">
!  <OVERVIEW>
!   get_field_index returns returns the index associated with an 
!   integral name.
!  </OVERVIEW>
!  <DESCRIPTION>
!   get_field_index returns returns the index associated with an 
!   integral name.
!  </DESCRIPTION>
!  <TEMPLATE>
!   index = get_field_index (name)
!  </TEMPLATE>
!  <IN NAME="name" TYPE="real">
!   Name associated with an integral
!  </IN>
! </FUNCTION>
!
function get_field_index (name) result (index)

!---------------------------------------------------------------------
!   get_field_index returns returns the index associated with an 
!   integral name.
!---------------------------------------------------------------------

character(len=*),  intent(in) :: name
integer                       :: index

!--------------------------------------------------------------------
!  intent(in) variables:
!
!       name
!
!   result:
!
!       index
!
!--------------------------------------------------------------------

!---------------------------------------------------------------------
!   local variables:

      integer :: nc
      integer :: i

!---------------------------------------------------------------------
!
!--------------------------------------------------------------------
      nc = len_trim (name)
      if (nc > max_len_name)  then
        call error_mesg ('diag_integral_mod',  &
                                        'name too long', FATAL)
      endif

!--------------------------------------------------------------------
!    search each field name for the current string. when found exit
!    with the index. if not found index will be 0 upon return, which
!    initiates error condition.
!--------------------------------------------------------------------
      index = 0
      do i = 1, num_field
        if (name(1:nc) ==     &
                       field_name(i) (1:len_trim(field_name(i))) ) then
          index = i
          exit
        endif
      end do

!---------------------------------------------------------------------



 end function get_field_index


!#####################################################################
! <SUBROUTINE NAME="write_field_averages">
!  <OVERVIEW>
!    Subroutine to sum multiple fields, average them and then write the result
!    to an output file.
!  </OVERVIEW>
!  <DESCRIPTION>
!    Subroutine to sum multiple fields, average them and then write the result
!    to an output file.
!  </DESCRIPTION>
!  <TEMPLATE>
!   call  write_field_averages (Time)
!  </TEMPLATE>
!  <IN NAME="Time" TYPE="time_type">
!   integral time stamp at the current time 
!  </IN>
! </SUBROUTINE>
!
subroutine write_field_averages (Time)

!---------------------------------------------------------------------
!
!---------------------------------------------------------------------

type (time_type), intent(in) :: Time

!--------------------------------------------------------------------
!  intent(in) variables:
!
!      Time
!
!--------------------------------------------------------------------

!--------------------------------------------------------------------
!   local variables:

      real    :: field_avg(max_num_field)
      real    :: xtime, rcount
      integer :: nn, ninc, nst, nend, fields_to_print
      integer :: i, kount
      integer(LONG_KIND) :: icount
!--------------------------------------------------------------------
!   local variables:
!
!      field_avg
!      xtime
!      rcount
!      nn
!      ninc
!      nst
!      nend
!      fields_to_print
!      i
!      kount
!
!--------------------------------------------------------------------

!--------------------------------------------------------------------
!    each header and data format may be different and must be generated
!    as needed.
!---------------------------------------------------------------------- 
      fields_to_print = 0
      do i = 1, num_field

!--------------------------------------------------------------------
!    increment the fields_to_print counter.  sum the integrand and the
!    number of data points contributing to it over all processors. 
!--------------------------------------------------------------------
        fields_to_print = fields_to_print + 1
        rcount = real(field_count(i))
        call mpp_sum (rcount)
        call mpp_sum (field_sum(i))
        icount = rcount

!--------------------------------------------------------------------
!    verify that all the data expected for an integral has been 
!    obtained.
!--------------------------------------------------------------------
        if (icount == 0 ) call error_mesg &
                     ('diag_integral_mod',  &
                      'field_count equals zero for field_name ' //  &
                       field_name(i)(1:len_trim(field_name(i))), FATAL )
        kount = icount/field_size
        if ((field_size)*kount /= icount) then
           print*,"name,pe,kount,field_size,icount,rcount=",trim(field_name(i)),mpp_pe(),kount,field_size,icount,rcount
           call error_mesg &
                 ('diag_integral_mod',  &
                  'field_count not a multiple of field_size', FATAL )
        endif
!----------------------------------------------------------------------
!    define the global integral for field i. reinitialize the point
!    and data accumulators.
!----------------------------------------------------------------------
        field_avg(fields_to_print) = field_sum(i)/  &
                                     (sum_area*float(kount))
        field_sum  (i) = 0.0
        field_count(i) = 0
      end do

!--------------------------------------------------------------------
!    only the root pe will write out data.
!--------------------------------------------------------------------
      if ( mpp_pe() /= mpp_root_pe() ) return

!---------------------------------------------------------------------
!    define the time associated with the integrals just calculated.
!---------------------------------------------------------------------
      xtime = get_axis_time (Time-Time_init_save, time_units)

!---------------------------------------------------------------------
!    generate the new header and data formats.
!---------------------------------------------------------------------
      nst = 1
      nend = fields_per_print_line
      ninc = (num_field-1)/fields_per_print_line + 1
      do nn=1, ninc
        nst = 1 + (nn-1)*fields_per_print_line
        nend = MIN (nn*fields_per_print_line, num_field)
        if (print_header)  call format_text_init (nst, nend)
        call format_data_init (nst, nend)
        if (diag_unit /= 0) then
          write (diag_unit,format_data(1:nd)) &
                 xtime, (field_avg(i),i=nst,nend)
        else
          write (*, format_data(1:nd)) &
                 xtime, (field_avg(i),i=nst,nend)
        endif
      end do

!-----------------------------------------------------------------------


end subroutine write_field_averages




!#######################################################################
! <SUBROUTINE NAME="format_text_init">
!  <OVERVIEW>
!    format_text_init generates the header records to be output in the
!    integrals file.
!  </OVERVIEW>
!  <DESCRIPTION>
!    format_text_init generates the header records to be output in the
!    integrals file.
!  </DESCRIPTION>
!  <TEMPLATE>
!   call  format_text_init (nst_in, nend_in)
!  </TEMPLATE>
!  <IN NAME="nst_in, nend_in" TYPE="integer">
!    starting/ending integral index which will be included
!                    in this format statement
!  </IN>
! </SUBROUTINE>
!
subroutine format_text_init (nst_in, nend_in)

!----------------------------------------------------------------------
!    format_text_init generates the header records to be output in the
!    integrals file.
!----------------------------------------------------------------------

integer, intent(in), optional :: nst_in, nend_in

!---------------------------------------------------------------------
!  intent(in),optional variables:
!
!       nst_in       starting integral index which will be included
!                    in this format statement
!       nend_in      ending integral index which will be included
!                    in this format statement
!
!--------------------------------------------------------------------

!--------------------------------------------------------------------
!   local variables:

      integer :: i, nc, nst, nend

!--------------------------------------------------------------------
!   local variables:
!
!        i
!        nc
!        nst
!        nend
! 
!---------------------------------------------------------------------

!---------------------------------------------------------------------
!    only the root pe need execute this routine, since only it will 
!    be outputting integrals.
!---------------------------------------------------------------------
      if (mpp_pe() /= mpp_root_pe()) return

!----------------------------------------------------------------------
!    define the starting and ending integral indices that will be
!    included in this format statement.
!----------------------------------------------------------------------
      if (present (nst_in) ) then
        nst = nst_in
        nend = nend_in
      else
        nst = 1
        nend = num_field
      endif

!--------------------------------------------------------------------
!    define the first 11 characters in the format statement.
!--------------------------------------------------------------------
      nt = 11
      format_text(1:nt) = "('#    time"

!--------------------------------------------------------------------
!    generate the rest of the format statement, which will cover
!    integral indices nst to nend. if satndard printout is desired,
!    cycle through the loop.
!--------------------------------------------------------------------
      do i=nst,nend
        nc = len_trim(field_name(i))
        format_text(nt+1:nt+nc+5) =  '     ' // field_name(i)(1:nc)
        nt = nt+nc+5
      end do

!---------------------------------------------------------------------
!    include the end of the format statement.
!---------------------------------------------------------------------
      format_text(nt+1:nt+2) = "')"
      nt = nt+2

!--------------------------------------------------------------------
!    write the format statement to either an output file or to stdout.
!--------------------------------------------------------------------
      if (diag_unit /= 0) then
        write (diag_unit, format_text(1:nt))
      else
        write (*, format_text(1:nt))
      endif

!---------------------------------------------------------------------


end subroutine format_text_init



!#######################################################################
! <SUBROUTINE NAME="format_data_init">
!  <OVERVIEW>
!    format_text_init generates the format to be output in the
!    integrals file.
!  </OVERVIEW>
!  <DESCRIPTION>
!    format_text_init generates the format to be output in the
!    integrals file.
!  </DESCRIPTION>
!  <TEMPLATE>
!   call  format_data_init (nst_in, nend_in)
!  </TEMPLATE>
!  <IN NAME="nst_in, nend_in" TYPE="integer">
!    starting/ending integral index which will be included
!                    in this format statement
!  </IN>
! </SUBROUTINE>
!
subroutine format_data_init (nst_in, nend_in)

!---------------------------------------------------------------------
!    format_data_init generates the format that will write out the
!    integral data.
!---------------------------------------------------------------------

integer, intent(in), optional :: nst_in, nend_in
   
!--------------------------------------------------------------------
!  intent(in),optional variables:
!
!       nst_in       starting integral index which will be included
!                    in this format statement
!       nend_in      ending integral index which will be included
!                    in this format statement
!
!--------------------------------------------------------------------

!--------------------------------------------------------------------
!   local variables:

      integer :: i, nc, nst, nend

!--------------------------------------------------------------------
!   local variables:
!
!        i
!        nc
!        nst
!        nend
! 
!---------------------------------------------------------------------

!--------------------------------------------------------------------
!    define the start of the format, which covers the time stamp of the
!    integrals. this section is 9 characters long.
!--------------------------------------------------------------------
      nd = 9
      format_data(1:nd) = '(1x,f10.2'

!--------------------------------------------------------------------
!    define the indices of the integrals that are to be written by this
!    format statement.
!--------------------------------------------------------------------
      if ( present (nst_in) ) then
        nst = nst_in
        nend = nend_in
      else
        nst = 1 
        nend = num_field
      endif

!-------------------------------------------------------------------
!    complete the data format. use the format defined for the 
!    particular integral in setting up the format statement.
!-------------------------------------------------------------------
      do i=nst,nend
         nc = len_trim(field_format(i))
         format_data(nd+1:nd+nc+5) =  ',1x,' // field_format(i)(1:nc)
         nd = nd+nc+5
      end do

!-------------------------------------------------------------------
!    close the format statement.
!-------------------------------------------------------------------
      format_data(nd+1:nd+1) = ')'
      nd = nd + 1

!-------------------------------------------------------------------



end subroutine format_data_init



!#######################################################################
! <FUNCTION NAME="get_axis_time">
!  <OVERVIEW>
!    Function to convert the time_type input variable into units of
!    units and returns it in atime.
!  </OVERVIEW>
!  <DESCRIPTION>
!    Function to convert the time_type input variable into units of
!    units and returns it in atime.
!  </DESCRIPTION>
!  <TEMPLATE>
!   atime = get_axis_time (Time, units)
!  </TEMPLATE>
!  <IN NAME="Time" TYPE="time_type">
!   integral time stamp
!  </IN>
!  <IN NAME="units" TYPE="character">
!   input units of time_type
!  </IN>
! </FUNCTION>
!
function get_axis_time (Time, units) result (atime)

!---------------------------------------------------------------------
!
!---------------------------------------------------------------------

type(time_type),  intent(in) :: Time
character(len=*), intent(in) :: units
real                         :: atime

!----------------------------------------------------------------------
!  intent(in) variables:
!
!      Time
!      units
!
!  result:
!
!      atime
!
!---------------------------------------------------------------------

!---------------------------------------------------------------------
!   local variables:

      integer      :: sec, day  ! components of time_type variable

!-------------------------------------------------------------------
!    get_axis_time converts the time_type input variable into units of
!    units and returns it in atime.
!-------------------------------------------------------------------
      call get_time (Time, sec, day)
      if (units(1:3) == 'sec') then
         atime = float(sec) + 86400.*float(day)
      else if (units(1:3) == 'min') then
         atime = float(sec)/60. + 1440.*float(day)
      else if (units(1:3) == 'hou') then
         atime = float(sec)/3600. + 24.*float(day)
      else if (units(1:3) == 'day') then
         atime = float(sec)/86400. + float(day)
      endif

!--------------------------------------------------------------------
 


end function get_axis_time



!#####################################################################
! <FUNCTION NAME="diag_integral_alarm">
!  <OVERVIEW>
!   Function to check if it is time to write integrals. 
!   if not writing integrals, return.
!  </OVERVIEW>
!  <DESCRIPTION>
!   Function to check if it is time to write integrals. 
!   if not writing integrals, return.
!  </DESCRIPTION>
!  <TEMPLATE>
!   result = diag_integral_alarm (Time)
!  </TEMPLATE>
!  <IN NAME="Time" TYPE="time_type">
!   current time
!  </IN>
! </FUNCTION>
!
 function diag_integral_alarm (Time) result (answer)

!--------------------------------------------------------------------
!
!--------------------------------------------------------------------

type (time_type), intent(in) :: Time
logical                      :: answer

!---------------------------------------------------------------------
!  intent(in) variables:
!
!      Time
!
!  result:
!
!      answer
!
!---------------------------------------------------------------------

!--------------------------------------------------------------------
!    check if it is time to write integrals. if not writing integrals,
!    return.
!--------------------------------------------------------------------
      answer = .false.
      if (Alarm_interval == Zero_time) return
      if (Time >= Next_alarm_time) answer = .true.

!--------------------------------------------------------------------


end function diag_integral_alarm



!#######################################################################
! <FUNCTION NAME="vert_diag_integral">
!  <OVERVIEW>
!   Function to perform a weighted integral in the vertical 
!    direction of a 3d data field
!  </OVERVIEW>
!  <DESCRIPTION>
!   Function to perform a weighted integral in the vertical 
!    direction of a 3d data field
!  </DESCRIPTION>
!  <TEMPLATE>
!   data2 = vert_diag_integral (data, wt)
!  </TEMPLATE>
!  <IN NAME="data" TYPE="real">
!   integral field data arrays
!  </IN>
!  <IN NAME="wt" TYPE="real">
!   integral field weighting functions
!  </IN>
! </FUNCTION>
!
function vert_diag_integral (data, wt) result (data2)

!----------------------------------------------------------------------
!
!----------------------------------------------------------------------

real, dimension (:,:,:),         intent(in) :: data, wt
real, dimension (size(data,1),size(data,2)) :: data2

!---------------------------------------------------------------------
!  intent(in) variables;
!
!      data
!      wt
!
!  result:
!      data2
! 
!---------------------------------------------------------------------

!---------------------------------------------------------------------
!  local variables:
 
      real, dimension(size(data,1),size(data,2)) :: wt2

!---------------------------------------------------------------------
!  local variables:
!
!       wt2
!
!---------------------------------------------------------------------

!--------------------------------------------------------------------
      wt2 = sum(wt,3)
      if (count(wt2 == 0.) > 0)  then
        call error_mesg ('diag_integral_mod',  &
                             'vert sum of weights equals zero', FATAL)
      endif
      data2 = sum(data*wt,3) / wt2

!---------------------------------------------------------------------


 end function vert_diag_integral




!#######################################################################




                    end module diag_integral_mod

