mpp_io.F90

!***********************************************************************
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!-----------------------------------------------------------------------
!                 Parallel I/O for message-passing codes
!
! AUTHOR: V. Balaji (vb@gfdl.gov)
!         SGI/GFDL Princeton University
!
!-----------------------------------------------------------------------
 
!> @defgroup mpp_io_mod mpp_io_mod
!> @ingroup mpp
!> @brief a set of simple calls for parallel I/O on
!!   distributed systems. It is geared toward the writing of data in netCDF
!!   format
!> @author V. Balaji <"vb@gfdl.noaa.gov">
!!
!> In massively parallel environments, an often difficult problem is
!! the reading and writing of data to files on disk. MPI-IO and MPI-2 IO
!! are moving toward providing this capability, but are currently not
!! widely implemented. Further, it is a rather abstruse
!! API. @ref mpp_io_mod is an attempt at a simple API encompassing a
!! certain variety of the I/O tasks that will be required. It does not
!! attempt to be an all-encompassing standard such as MPI, however, it
!! can be implemented in MPI if so desired. It is equally simple to add
!! parallel I/O capability to @ref mpp_io_mod based on vendor-specific
!! APIs while providing a layer of insulation for user codes.
!!
!! The @ref mpp_io_mod parallel I/O API built on top of the <LINK
!! SRC="mpp_domains.html">mpp_domains_mod</LINK> and <LINK
!! SRC="mpp.html">mpp_mod</LINK> API for domain decomposition and
!! message passing. Features of @ref mpp_io_mod include:
!!
!! 1) Simple, minimal API, with free access to underlying API for more
!! complicated stuff.<BR/>
!! 2) Self-describing files: comprehensive header information
!! (metadata) in the file itself.<BR/>
!! 3) Strong focus on performance of parallel write: the climate models
!! for which it is designed typically read a minimal amount of data
!! (typically at the beginning of the run); but on the other hand, tend
!! to write copious amounts of data during the run. An interface for
!! reading is also supplied, but its performance has not yet been optimized.<BR/>
!! 4) Integrated netCDF capability: <LINK SRC
!! ="http://www.unidata.ucar.edu/packages/netcdf/">netCDF</LINK> is a
!! data format widely used in the climate/weather modeling
!! community. netCDF is considered the principal medium of data storage
!! for @ref mpp_io_mod. But I provide a raw unformatted
!! fortran I/O capability in case netCDF is not an option, either due to
!! unavailability, inappropriateness, or poor performance.<BR/>
!! 5) May require off-line post-processing: a tool for this purpose,
!! <TT>mppnccombine</TT>, is available. GFDL users may use
!! <TT>~hnv/pub/mppnccombine</TT>. Outside users may obtain the
!! source <LINK SRC
!! ="ftp://ftp.gfdl.gov/perm/hnv/mpp/mppnccombine.c">here</LINK>.  It
!! can be compiled on any C compiler and linked with the netCDF
!! library. The program is free and is covered by the <LINK SRC
!! ="ftp://ftp.gfdl.gov/perm/hnv/mpp/LICENSE">GPL license</LINK>.
!!
!! The internal representation of the data being written out is
!! assumed be the default real type, which can be 4 or 8-byte. Time data
!! is always written as 8-bytes to avoid overflow on climatic time scales
!! in units of seconds.
!!
!! <LINK SRC="modes"></LINK><H4>I/O modes in @ref mpp_io_mod</H4>
!!
!! The I/O activity critical to performance in the models for which
!! @ref mpp_io_mod is designed is typically the writing of large
!! datasets on a model grid volume produced at intervals during
!! a run. Consider a 3D grid volume, where model arrays are stored as
!! <TT>(i,j,k)</TT>. The domain decomposition is typically along
!! <TT>i</TT> or <TT>j</TT>: thus to store data to disk as a global
!! volume, the distributed chunks of data have to be seen as
!! non-contiguous. If we attempt to have all PEs write this data into a
!! single file, performance can be seriously compromised because of the
!! data reordering that will be required. Possible options are to have
!! one PE acquire all the data and write it out, or to have all the PEs
!! write independent files, which are recombined offline. These three
!! modes of operation are described in the @ref mpp_io_mod terminology
!! in terms of two parameters, <I>threading</I> and <I>fileset</I>,
!! as follows:
!!
!! <I>Single-threaded I/O:</I> a single PE acquires all the data
!! and writes it out.<BR/>
!! <I>Multi-threaded, single-fileset I/O:</I> many PEs write to a
!! single file.<BR/>
!! <I>Multi-threaded, multi-fileset I/O:</I> many PEs write to
!! independent files. This is also called <I>distributed I/O</I>.
!!
!! The middle option is the most difficult to achieve performance. The
!! choice of one of these modes is made when a file is opened for I/O, in
!! <LINK SRC="#mpp_open">mpp_open</LINK>.
!!
!! <LINK name="metadata"></LINK><H4>Metadata in @ref mpp_io_mod</H4>
!!
!! A requirement of the design of @ref mpp_io_mod is that the file must
!! be entirely self-describing: comprehensive header information
!! describing its contents is present in the header of every file. The
!! header information follows the model of netCDF. Variables in the file
!! are divided into <I>axes</I> and <I>fields</I>. An axis describes a
!! co-ordinate variable, e.g <TT>x,y,z,t</TT>. A field consists of data in
!! the space described by the axes. An axis is described in
!! @ref mpp_io_mod using the defined type <TT>axistype</TT>:
!!
!! <PRE>
!!   type, public :: axistype
!!      sequence
!!      character(len=128) :: name
!!      character(len=128) :: units
!!      character(len=256) :: longname
!!      character(len=8) :: cartesian
!!      integer :: len
!!      integer :: sense           !+/-1, depth or height?
!!      type(domain1D), pointer :: domain
!!      real, dimension(:), pointer :: data
!!      integer :: id, did
!!      integer :: type  ! external NetCDF type format for axis data
!!      integer :: natt
!!      type(atttype), pointer :: Att(:) ! axis attributes
!!   end type axistype
!!   </PRE>
!!
!!   A field is described using the type <TT>fieldtype</TT>:
!!
!!   <PRE>
!!   type, public :: fieldtype
!!      sequence
!!      character(len=128) :: name
!!      character(len=128) :: units
!!      character(len=256) :: longname
!!      real :: min, max, missing, fill, scale, add
!!      integer :: pack
!!      type(axistype), dimension(:), pointer :: axes
!!      integer, dimension(:), pointer :: size
!!      integer :: time_axis_index
!!      integer :: id
!!      integer :: type ! external NetCDF format for field data
!!      integer :: natt, ndim
!!      type(atttype), pointer :: Att(:) ! field metadata
!!   end type fieldtype
!!   </PRE>
!!
!!   An attribute (global, field or axis) is described using the <TT>atttype</TT>:
!!
!!   <PRE>
!!   type, public :: atttype
!!      sequence
!!      integer :: type, len
!!      character(len=128) :: name
!!      character(len=256)  :: catt
!!      real(r4_kind), pointer :: fatt(:)
!!   end type atttype
!!   </PRE>
!!
!!   <LINK name="packing"></LINK>This default set of field attributes corresponds
!!   closely to various conventions established for netCDF files. The
!!   <TT>pack</TT> attribute of a field defines whether or not a
!!   field is to be packed on output. Allowed values of
!!   <TT>pack</TT> are 1,2,4 and 8. The value of
!!   <TT>pack</TT> is the number of variables written into 8
!!   bytes. In typical use, we write 4-byte reals to netCDF output; thus
!!   the default value of <TT>pack</TT> is 2. For
!!   <TT>pack</TT> = 4 or 8, packing uses a simple-minded linear
!!   scaling scheme using the <TT>scale</TT> and <TT>add</TT>
!!   attributes. There is thus likely to be a significant loss of dynamic
!!   range with packing. When a field is declared to be packed, the
!!   <TT>missing</TT> and <TT>fill</TT> attributes, if
!!   supplied, are packed also.
!!
!!   Please note that the pack values are the same even if the default
!!   real is 4 bytes, i.e <TT>PACK=1</TT> still follows the definition
!!   above and writes out 8 bytes.
!!
!!   A set of <I>attributes</I> for each variable is also available. The
!!   variable definitions and attribute information is written/read by calling
!!   <LINK SRC="#mpp_write_meta">mpp_write_meta</LINK> or <LINK SRC="#mpp_read_meta">mpp_read_meta</LINK>. A typical
!!   calling sequence for writing data might be:
!!
!!   <PRE>
!!   ...
!!     type(domain2D), dimension(:), allocatable, target :: domain
!!     type(fieldtype) :: field
!!     type(axistype) :: x, y, z, t
!!   ...
!!     call mpp_define_domains( (/1,nx,1,ny/), domain )
!!     allocate( a(domain(pe)%x%data%start_index:domain(pe)%x%data%end_index, &
!!                 domain(pe)%y%data%start_index:domain(pe)%y%data%end_index,nz) )
!!   ...
!!     call mpp_write_meta( unit, x, 'X', 'km', 'X distance', &
!!          domain=domain(pe)%x, data=(/(float(i),i=1,nx)/) )
!!     call mpp_write_meta( unit, y, 'Y', 'km', 'Y distance', &
!!          domain=domain(pe)%y, data=(/(float(i),i=1,ny)/) )
!!     call mpp_write_meta( unit, z, 'Z', 'km', 'Z distance', &
!!          data=(/(float(i),i=1,nz)/) )
!!     call mpp_write_meta( unit, t, 'Time', 'second', 'Time' )
!!
!!     call mpp_write_meta( unit, field, (/x,y,z,t/), 'a', '(m/s)', AAA', &
!!          missing=-1e36 )
!!   ...
!!     call mpp_write( unit, x )
!!     call mpp_write( unit, y )
!!     call mpp_write( unit, z )
!!   ...
!!   </PRE>
!!
!!   In this example, <TT>x</TT> and <TT>y</TT> have been
!!   declared as distributed axes, since a domain decomposition has been
!!   associated. <TT>z</TT> and <TT>t</TT> are undistributed
!!   axes. <TT>t</TT> is known to be a <I>record</I> axis (netCDF
!!   terminology) since we do not allocate the <TT>data</TT> element
!!   of the <TT>axistype</TT>. <I>Only one record axis may be
!!   associated with a file.</I> The call to <LINK
!!   SRC="#mpp_write_meta">mpp_write_meta</LINK> initializes
!!   the axes, and associates a unique variable ID with each axis. The call
!!   to <TT>mpp_write_meta</TT> with argument <TT>field</TT>
!!   declared <TT>field</TT> to be a 4D variable that is a function
!!   of <TT>(x,y,z,t)</TT>, and a unique variable ID is associated
!!   with it. A 3D field will be written at each call to
!!   <TT>mpp_write(field)</TT>.
!!
!!   The data to any variable, including axes, is written by
!!   <TT>mpp_write</TT>.
!!
!!   Any additional attributes of variables can be added through
!!   subsequent <TT>mpp_write_meta</TT> calls, using the variable ID as a
!!   handle. <I>Global</I> attributes, associated with the dataset as a
!!   whole, can also be written thus. See the <LINK
!!   SRC="#mpp_write_meta">mpp_write_meta</LINK> call syntax below
!!   for further details.
!!
!!   You cannot interleave calls to <TT>mpp_write</TT> and
!!   <TT>mpp_write_meta</TT>: the first call to
!!   <TT>mpp_write</TT> implies that metadata specification is
!!   complete.
!!
!!   A typical calling sequence for reading data might be:
!!
!!   <PRE>
!!   ...
!!     integer :: unit, natt, nvar, ntime
!!     type(domain2D), dimension(:), allocatable, target :: domain
!!     type(fieldtype), allocatable, dimension(:) :: fields
!!     type(atttype), allocatable, dimension(:) :: global_atts
!!     real, allocatable, dimension(:) :: times
!!   ...
!!     call mpp_define_domains( (/1,nx,1,ny/), domain )
!!
!!     call mpp_read_meta(unit)
!!     call mpp_get_info(unit,natt,nvar,ntime)
!!     allocate(global_atts(natt))
!!     call mpp_get_atts(unit,global_atts)
!!     allocate(fields(nvar))
!!     call mpp_get_vars(unit, fields)
!!     allocate(times(ntime))
!!     call mpp_get_times(unit, times)
!!
!!     allocate( a(domain(pe)%x%data%start_index:domain(pe)%x%data%end_index, &
!!                 domain(pe)%y%data%start_index:domain(pe)%y%data%end_index,nz) )
!!   ...
!!     do i=1, nvar
!!       if (fields(i)%name == 'a')  call mpp_read(unit,fields(i),domain(pe), a,
!!                                                 tindex)
!!     enddo
!!   ...
!!   </PRE>
!!
!!   In this example, the data are distributed as in the previous
!!   example. The call to <LINK
!!   SRC="#mpp_read_meta">mpp_read_meta</LINK> initializes
!!   all of the metadata associated with the file, including global
!!   attributes, variable attributes and non-record dimension data. The
!!   call to <TT>mpp_get_info</TT> returns the number of global
!!   attributes (<TT>natt</TT>), variables (<TT>nvar</TT>) and
!!   time levels (<TT>ntime</TT>) associated with the file
!!   identified by a unique ID (<TT>unit</TT>).
!!   <TT>mpp_get_atts</TT> returns all global attributes for
!!   the file in the derived type <TT>atttype(natt)</TT>.
!!   <TT>mpp_get_vars</TT> returns variable types
!!   (<TT>fieldtype(nvar)</TT>).  Since the record dimension data are not allocated for calls to
!!   <LINK SRC="#mpp_write">mpp_write</LINK>, a separate call to  <TT>mpp_get_times</TT> is required to access record
!!   dimension data.  Subsequent calls to
!!   <TT>mpp_read</TT> return the field data arrays corresponding to
!!   the fieldtype.  The <TT>domain</TT> type is an optional
!!   argument.  If <TT>domain</TT> is omitted, the incoming field
!!   array should be dimensioned for the global domain, otherwise, the
!!   field data is assigned to the computational domain of a local array.
!!
!!   <I>Multi-fileset</I> reads are not supported with <TT>mpp_read</TT>.
!!
!! </DESCRIPTION>
!! @endhtmlonly
 
!> @addtogroup mpp_io_mod
!> @{
 
module mpp_io_mod
#ifdef use_deprecated_io
 
#define _MAX_FILE_UNITS 1024
 
#ifdef use_netCDF
use netcdf
use netcdf_nf_data
use netcdf_nf_interfaces
use netcdf4_nf_interfaces
#endif
 
use mpp_parameter_mod,  only : mpp_wronly, mpp_rdonly, mpp_append, mpp_overwr, mpp_ascii
use mpp_parameter_mod,  only : mpp_ieee32, mpp_native, mpp_netcdf, mpp_sequential
use mpp_parameter_mod,  only : mpp_direct, mpp_single, mpp_multi, mpp_delete, mpp_collect
use mpp_parameter_mod,  only : mpp_debug, mpp_verbose, nullunit, nulltime, all_pes
use mpp_parameter_mod,  only : center, east, north, corner
use mpp_parameter_mod,  only : max_file_size, global_root_only, xupdate, yupdate
use mpp_mod,            only : mpp_error, fatal, warning, note, stdin, stdout, stderr, stdlog
use mpp_mod,            only : mpp_pe, mpp_root_pe, mpp_npes, lowercase, mpp_transmit, mpp_sync_self
use mpp_mod,            only : mpp_init, mpp_sync, mpp_clock_id, mpp_clock_begin, mpp_clock_end
use mpp_mod,            only : mpp_clock_sync, mpp_clock_detailed, clock_routine
use mpp_mod,            only : input_nml_file, mpp_gather, mpp_broadcast
use mpp_mod,            only : mpp_send, mpp_recv, mpp_sync_self, event_recv, comm_tag_1
use mpp_domains_mod,    only : domain1d, domain2d, null_domain1d, mpp_domains_init
use mpp_domains_mod,    only : mpp_get_global_domain, mpp_get_compute_domain
use mpp_domains_mod,    only : mpp_get_data_domain, mpp_get_memory_domain, mpp_get_pelist
use mpp_domains_mod,    only : mpp_update_domains, mpp_global_field, mpp_domain_is_symmetry
use mpp_domains_mod,    only : operator( .NE. ), mpp_get_domain_shift, mpp_get_ug_compute_domains
use mpp_domains_mod,    only : mpp_get_io_domain, mpp_domain_is_tile_root_pe, mpp_get_domain_tile_root_pe
use mpp_domains_mod,    only : mpp_get_tile_id, mpp_get_tile_npes, mpp_get_io_domain_layout
use mpp_domains_mod,    only : mpp_get_domain_name, mpp_get_domain_npes
use mpp_parameter_mod,  only : mpp_fill_double,mpp_fill_int
use mpp_mod,            only : mpp_chksum
 
!----------
!ug support
use mpp_domains_mod, only: domainug, &
                           mpp_get_ug_io_domain, &
                           mpp_domain_ug_is_tile_root_pe, &
                           mpp_get_ug_domain_tile_id, &
                           mpp_get_ug_domain_npes, &
                           mpp_get_io_domain_ug_layout, &
                           mpp_get_ug_compute_domain, &
                           mpp_get_ug_domain_pelist
use platform_mod
!----------
 
implicit none
private
 
  !--- public parameters  -----------------------------------------------
  public :: mpp_wronly, mpp_rdonly, mpp_append, mpp_overwr, mpp_ascii, mpp_ieee32
  public :: mpp_native, mpp_netcdf, mpp_sequential, mpp_direct, mpp_single
  public :: mpp_multi, mpp_delete, mpp_collect
  public :: file_type_used
  public :: max_file_size
  !--- public data type ------------------------------------------------
  public :: axistype, atttype, fieldtype, validtype, filetype
 
  !--- public data -----------------------------------------------------
  public :: default_field, default_axis, default_att
 
  !--- public interface from mpp_io_util.h ----------------------
  public :: mpp_get_id, mpp_get_ncid, mpp_is_valid
  public :: mpp_get_info, mpp_get_atts, mpp_get_fields
  public :: mpp_get_times, mpp_get_axes, mpp_get_recdimid, mpp_get_axis_data, mpp_get_axis_by_name
  public :: mpp_io_set_stack_size, mpp_get_field_index, mpp_get_axis_index
  public :: mpp_get_field_name, mpp_get_att_value, mpp_get_att_length
  public :: mpp_get_att_type, mpp_get_att_name, mpp_get_att_real, mpp_get_att_char
  public :: mpp_get_att_real_scalar, mpp_get_axis_length, mpp_is_dist_ioroot
  public :: mpp_get_file_name, mpp_file_is_opened, mpp_attribute_exist
  public :: mpp_io_clock_on, mpp_get_time_axis, mpp_get_default_calendar
  public :: mpp_get_dimension_length, mpp_get_axis_bounds
 
  !--- public interface from mpp_io_misc.h ----------------------
  public :: mpp_io_init, mpp_io_exit, netcdf_err, mpp_flush, mpp_get_maxunits, do_cf_compliance
 
  !--- public interface from mpp_io_write.h ---------------------
  public :: mpp_write, mpp_write_meta, mpp_copy_meta, mpp_modify_meta, mpp_write_axis_data, mpp_def_dim
 
  !--- public interface from mpp_io_read.h ---------------------
  public :: mpp_read, mpp_read_meta, mpp_get_tavg_info
  public :: mpp_read_compressed, mpp_write_compressed, mpp_read_distributed_ascii, mpp_write_unlimited_axis
 
  !--- public interface from mpp_io_switch.h ---------------------
  public :: mpp_open, mpp_close
  public :: fillin_fieldtype
  !-----------------------------------------------------------------------------
  !--- mpp_io data types
  !-----------------------------------------------------------------------------
integer FILE_TYPE_USED
integer, parameter :: MAX_ATT_LENGTH = 1280
!> @}
!> @ingroup mpp_io_mod
type :: atttype
     private
     integer             :: type, len
     character(len=128)  :: name
     character(len=MAX_ATT_LENGTH) :: catt
     real, pointer       :: fatt(:) =>null() ! just use type conversion for integers
  end type atttype
 
  !> @ingroup mpp_io_mod
  type :: axistype
     private
     character(len=128) :: name
     character(len=128) :: name_bounds
     character(len=128) :: units
     character(len=256) :: longname
     character(len=8)   :: cartesian
     character(len=256) :: compressed
     character(len=24)  :: calendar
     integer            :: sense, len          !+/-1, depth or height?
     type(domain1D)     :: domain              !if pointer is associated, it is a distributed data axis
     real, pointer      :: data(:) =>null()    !axis values (not used if time axis)
     real, pointer      :: data_bounds(:) =>null()    !axis bounds values
     integer, pointer   :: idata(:) =>null()   !compressed axis valuesi
     integer            :: id, did, type, natt !id is the "variable ID", did is the "dimension ID":
                                               !netCDF requires 2 IDs for axes
     integer            :: shift               !normally is 0. when domain is symmetry, its value maybe 1.
     type(atttype), pointer :: Att(:) =>null()
  end type axistype
 
  !> @ingroup mpp_io_mod
  type :: validtype
     private
     logical :: is_range ! if true, then the data represent the valid range
     real    :: min,max  ! boundaries of the valid range or missing value
  end type validtype
 
  !> @ingroup mpp_io_mod
  type :: fieldtype
     private
     character(len=128)      :: name
     character(len=128)      :: units
     character(len=256)      :: longname
     character(len=256)      :: standard_name   ! CF standard name
     real                    :: min, max, missing, fill, scale, add
     integer                 :: pack
     integer(i8_kind), dimension(3) :: checksum
     type(axistype), pointer :: axes(:) =>null() !axes associated with field size, time_axis_index redundantly
                                        !hold info already contained in axes. it's clunky and inelegant,
                                        !but required so that axes can be shared among multiple files
     integer, pointer        :: size(:) =>null()
     integer                 :: time_axis_index
     integer                 :: id, type, natt, ndim
     type(atttype), pointer  :: Att(:) =>null()
     integer                 :: position ! indicate the location of the data ( CENTER, NORTH, EAST, CORNER )
  end type fieldtype
 
  !> @ingroup mpp_io_mod
  type :: filetype
     private
     character(len=256) :: name
     integer            :: action, format, access, threading, fileset, record, ncid
     logical            :: opened, initialized, nohdrs
     integer            :: time_level
     real(r8_kind)  :: time
     logical            :: valid
     logical            :: write_on_this_pe   ! indicate if will write out from this pe
     logical            :: read_on_this_pe    ! indicate if will read from this pe
     logical            :: io_domain_exist    ! indicate if io_domain exist or not.
     integer            :: id       !variable ID of time axis associated with file (only one time axis per file)
     integer            :: recdimid !dim ID of time axis associated with file (only one time axis per file)
     real(r8_kind), pointer :: time_values(:) =>null() ! time axis values are stored here instead of axis%data
                                                  ! since mpp_write assumes these values are not time values.
                                                  ! Not used in mpp_write
     ! additional elements of filetype for mpp_read (ignored for mpp_write)
     integer :: ndim, nvar, natt  ! number of dimensions, non-dimension variables and global attributes
                                  ! redundant axis types stored here and in associated fieldtype
                                  ! some axes are not used by any fields, i.e. "edges"
     type(axistype), pointer  :: axis(:) =>null()
     type(fieldtype), pointer :: var(:) =>null()
     type(atttype), pointer   :: att(:) =>null()
     type(domain2d), pointer  :: domain =>null()
!----------
!ug support
     type(domainUG),pointer :: domain_ug => null() !Is this actually pointed to?
!----------
  end type filetype
 
!> @addtogroup mpp_io_mod
!> @{
!***********************************************************************
!
!     public interface from mpp_io_util.h
!
!***********************************************************************
  interface mpp_get_id
     module procedure mpp_get_axis_id
     module procedure mpp_get_field_id
  end interface
 
! <INTERFACE NAME="mpp_get_atts">
!   <OVERVIEW>
!     Get file global metdata.
!   </OVERVIEW>
!   <DESCRIPTION>
!     Get file global metdata.
!   </DESCRIPTION>
!   <TEMPLATE>
!     call mpp_get_atts( unit, global_atts)
!   </TEMPLATE>
!  <IN NAME="unit"></IN>
!  <IN NAME="global_atts"></IN>
! </INTERFACE>
  !> @brief Get file global metadata.
  !!
  !> <br>Example usage:
  !!                    call mpp_get_atts( unit, global_atts)
  interface mpp_get_atts
     module procedure mpp_get_global_atts
     module procedure mpp_get_field_atts
     module procedure mpp_get_axis_atts
  end interface
 
  interface mpp_get_att_value
     module procedure mpp_get_field_att_text
  end interface
 
 
!***********************************************************************
!
!      public interface from mpp_io_read.h
!
!***********************************************************************
! <INTERFACE NAME="mpp_read">
!   <OVERVIEW>
!     Read from an open file.
!   </OVERVIEW>
!   <DESCRIPTION>
!      <TT>mpp_read</TT> is used to read data to the file on an I/O unit
!      using the file parameters supplied by <LINK
!      SRC="#mpp_open"><TT>mpp_open</TT></LINK>. There are two
!      forms of <TT>mpp_read</TT>, one to read
!      distributed field data, and one to read non-distributed field
!      data. <I>Distributed</I> data refer to arrays whose two
!      fastest-varying indices are domain-decomposed. Distributed data must
!      be 2D or 3D (in space). Non-distributed data can be 0-3D.
!
!      The <TT>data</TT> argument for distributed data is expected by
!      <TT>mpp_read</TT> to contain data specified on the <I>data</I> domain,
!      and will read the data belonging to the <I>compute</I> domain,
!      fetching data as required by the parallel I/O <LINK
!      SRC="#modes">mode</LINK> specified in the <TT>mpp_open</TT> call. This
!      is consistent with our definition of <LINK
!      SRC="http:mpp_domains.html#domains">domains</LINK>, where all arrays are
!      expected to be dimensioned on the data domain, and all operations
!      performed on the compute domain.
!   </DESCRIPTION>
!   <TEMPLATE>
!     call mpp_read( unit, field, data, time_index )
!   </TEMPLATE>
!   <TEMPLATE>
!     call mpp_read( unit, field, domain, data, time_index )
!   </TEMPLATE>
!  <IN NAME="unit"></IN>
!  <IN NAME="field"></IN>
!  <INOUT NAME="data"></INOUT>
!  <IN NAME="domain"></IN>
!  <IN NAME="time_index">
!     time_index is an optional argument. It is to be omitted if the
!     field was defined not to be a function of time. Results are
!     unpredictable if the argument is supplied for a time- independent
!     field, or omitted for a time-dependent field.
!  </IN>
!  <NOTE>
!     The type of read performed by <TT>mpp_read</TT> depends on
!     the file characteristics on the I/O unit specified at the <LINK
!     SRC="#mpp_open"><TT>mpp_open</TT></LINK> call. Specifically, the
!     format of the input data (e.g netCDF or IEEE) and the
!     <TT>threading</TT> flags, etc., can be changed there, and
!     require no changes to the <TT>mpp_read</TT>
!     calls. (<TT>fileset</TT> = MPP_MULTI is not supported by
!     <TT>mpp_read</TT>; IEEE is currently not supported).
!
!     Packed variables are unpacked using the <TT>scale</TT> and
!     <TT>add</TT> attributes.
!
!     <TT>mpp_read_meta</TT> must be called prior to calling <TT>mpp_read.</TT>
!  </NOTE>
! </INTERFACE>
  interface mpp_read
     module procedure mpp_read_2ddecomp_r2d_r4
     module procedure mpp_read_2ddecomp_r3d_r4
     module procedure mpp_read_2ddecomp_r4d_r4
     module procedure mpp_read_2ddecomp_r2d_r8
     module procedure mpp_read_2ddecomp_r3d_r8
     module procedure mpp_read_2ddecomp_r4d_r8
     module procedure mpp_read_region_r2d_r4
     module procedure mpp_read_region_r3d_r4
     module procedure mpp_read_region_r2d_r8
     module procedure mpp_read_region_r3d_r8
     module procedure mpp_read_r0d_r4
     module procedure mpp_read_r1d_r4
     module procedure mpp_read_r2d_r4
     module procedure mpp_read_r3d_r4
     module procedure mpp_read_r4d_r4
     module procedure mpp_read_r0d_r8
     module procedure mpp_read_r1d_r8
     module procedure mpp_read_r2d_r8
     module procedure mpp_read_r3d_r8
     module procedure mpp_read_r4d_r8
     module procedure mpp_read_text
  end interface
 
!***********************************************************************
!
!      public interfaces from mpp_io_read_distributed_ascii.inc
!
!***********************************************************************
! <INTERFACE NAME="mpp_read_distributed_ascii">
!   <OVERVIEW>
!     Read from an opened, ascii file, translating data to the desired format
!   </OVERVIEW>
!   <DESCRIPTION>
!     These routines are part of the mpp_read family. It is intended to
!     provide a general purpose, distributed, list directed read
!  </DESCRIPTION>
!   <TEMPLATE>
!     call mpp_read_distributed_ascii(unit,fmt,ssize,data,iostat)
!   </TEMPLATE>
!  <IN NAME="unit"></IN>
!  <IN NAME="fmt"></IN>
!  <IN NAME="ssize"></IN>
!  <INOUT NAME="data"></IN>
!  <OUT NAME="iostat">
!  </IN>
!  <NOTE>
!     <TT>mpp_read_distributed_ascii</TT>
!     The stripe size must be greater than or equal to 1. The stripe
!     size does not have to be a common denominator of the number of
!     MPI ranks.
!  </NOTE>
! </INTERFACE>
  interface mpp_read_distributed_ascii
     module procedure mpp_read_distributed_ascii_r1d
     module procedure mpp_read_distributed_ascii_i1d
     module procedure mpp_read_distributed_ascii_a1d
  end interface
 
 
!***********************************************************************
!
!      public interfaces from mpp_io_read_compressed.h
!
!***********************************************************************
! <INTERFACE NAME="mpp_read_compressed">
!   <OVERVIEW>
!     Read from an opened, sparse data, compressed file (e.g. land_model)
!   </OVERVIEW>
!   <DESCRIPTION>
!     These routines are similar to mpp_read except that they are designed
!     to handle sparse, compressed vectors of data such as from the
!     land model. Currently, the sparse vector may vary in z. Hence
!     the need for the rank 2 treatment.
!  </DESCRIPTION>
!   <TEMPLATE>
!     call mpp_read_compressed( unit, field, domain, data, time_index )
!   </TEMPLATE>
!  <IN NAME="unit"></IN>
!  <IN NAME="field"></IN>
!  <IN NAME="domain"></IN>
!  <INOUT NAME="data"></INOUT>
!  <IN NAME="time_index">
!     time_index is an optional argument. It is to be omitted if the
!     field was defined not to be a function of time. Results are
!     unpredictable if the argument is supplied for a time- independent
!     field, or omitted for a time-dependent field.
!  </IN>
!  <NOTE>
!     <TT>mpp_read_meta</TT> must be called prior to calling
!     <TT>mpp_read_compressed.</TT>
!     Since in general, the vector is distributed across the io-domain
!     The read expects the io_domain to be defined.
!  </NOTE>
! </INTERFACE>
  interface mpp_read_compressed
     module procedure mpp_read_compressed_r1d_r4
     module procedure mpp_read_compressed_r2d_r4
     module procedure mpp_read_compressed_r3d_r4
     module procedure mpp_read_compressed_r1d_r8
     module procedure mpp_read_compressed_r2d_r8
     module procedure mpp_read_compressed_r3d_r8
  end interface mpp_read_compressed
 
 
!***********************************************************************
!
!    public interface from mpp_io_write.h
!
!***********************************************************************
 
! <INTERFACE NAME="mpp_write_meta">
!   <OVERVIEW>
!     Write metadata.
!   </OVERVIEW>
!   <DESCRIPTION>
!     This routine is used to write the <LINK SRC="#metadata">metadata</LINK>
!     describing the contents of a file being written. Each file can contain
!     any number of fields, which are functions of 0-3 space axes and 0-1
!     time axes. (Only one time axis can be defined per file). The basic
!     metadata defined <LINK SRC="#metadata">above</LINK> for <TT>axistype</TT>
!     and <TT>fieldtype</TT> are written in the first two forms of the call
!     shown below. These calls will associate a unique variable ID with each
!     variable (axis or field). These can be used to attach any other real,
!     integer or character attribute to a variable. The last form is used to
!     define a <I>global</I> real, integer or character attribute that
!     applies to the dataset as a whole.
!   </DESCRIPTION>
!  <TEMPLATE>
!    call mpp_write_meta( unit, axis, name, units, longname,
!      cartesian, sense, domain, data )
!  </TEMPLATE>
!  <NOTE>
!    The first form defines a time or space axis. Metadata corresponding to the type
!    above are written to the file on &lt;unit&gt;. A unique ID for subsequen
!    references to this axis is returned in axis%id. If the &lt;domain&gt;
!    element is present, this is recognized as a distributed data axis
!    and domain decomposition information is also written if required (the
!    domain decomposition info is required for multi-fileset multi-threaded
!    I/O). If the &lt;data&gt; element is allocated, it is considered to be a
!    space axis, otherwise it is a time axis with an unlimited dimension. Only
!    one time axis is allowed per file.
!  </NOTE>
!  <TEMPLATE>
!    call mpp_write_meta( unit, field, axes, name, units, longname,
!                              min, max, missing, fill, scale, add, pack )
!  </TEMPLATE>
!  <NOTE>
!    The second form defines a field. Metadata corresponding to the type
!    above are written to the file on &lt;unit&gt;. A unique ID for subsequen
!    references to this field is returned in field%id. At least one axis
!    must be associated, 0D variables are not considered. mpp_write_meta
!    must previously have been called on all axes associated with this
!    field.
!  </NOTE>
!  <TEMPLATE>
!    call mpp_write_meta( unit, id, name, rval=rval, pack=pack )
!  </TEMPLATE>
!  <TEMPLATE>
!    call mpp_write_meta( unit, id, name, ival=ival )
!  </TEMPLATE>
!  <TEMPLATE>
!    call mpp_write_meta( unit, id, name, cval=cval )
!  </TEMPLATE>
!  <NOTE>
!    The third form (3 - 5) defines metadata associated with a previously defined
!    axis or field, identified to mpp_write_meta by its unique ID &lt;id&gt;.
!    The attribute is named &lt;name&gt; and can take on a real, integer
!    or character value. &lt;rval&gt; and &lt;ival&gt; can be scalar or 1D arrays.
!    This need not be called for attributes already contained in
!    the type.
!  </NOTE>
!  <TEMPLATE>
!    call mpp_write_meta( unit, name, rval=rval, pack=pack )
!  </TEMPLATE>
!  <TEMPLATE>
!    call mpp_write_meta( unit, name, ival=ival )
!  </TEMPLATE>
!  <TEMPLATE>
!    call mpp_write_meta( unit, name, cval=cval )
!  </TEMPLATE>
!  <NOTE>
!    The last form (6 - 8) defines global metadata associated with the file as a
!    whole. The attribute is named &lt;name&gt; and can take on a real, integer
!    or character value. &lt;rval&gt; and &lt;ival&gt; can be scalar or 1D arrays.
!  </NOTE>
!  <IN NAME="unit"></IN>
!  <OUT NAME="axis"></OUT>
!  <IN NAME="name"></IN>
!  <IN NAME="units"></IN>
!  <IN NAME="longname"></IN>
!  <IN NAME="cartesian"></IN>
!  <IN NAME="sense"></IN>
!  <IN NAME="domain"></IN>
!  <IN NAME="data"></IN>
!  <OUT NAME="field"></OUT>
!  <IN NAME="min, max"></IN>
!  <IN NAME="missing"></IN>
!  <IN NAME="fill"></IN>
!  <IN NAME="scale"></IN>
!  <IN NAME="add"></IN>
!  <IN NAME="pack"></IN>
!  <IN NAME="id"></IN>
!  <IN NAME="cval"></IN>
!  <IN NAME="ival"></IN>
!  <IN NAME="rval"></IN>
 
!> Each file can contain any number of fields,
!! which can be functions of 0-3 spatial axes and 0-1 time axes. Axis
!! descriptors are stored in the <axistype> structure and field
!! descriptors in the <fieldtype> structure.
!!
!! The metadata contained in the type is always written for each axis and
!! field. Any other metadata one wishes to attach to an axis or field
!! can subsequently be passed to mpp_write_meta using the ID, as shown below.
!!
!! mpp_write_meta can take several forms:
!!
!!  mpp_write_meta( unit, name, rval=rval, pack=pack )
!!  mpp_write_meta( unit, name, ival=ival )
!!  mpp_write_meta( unit, name, cval=cval )
!!      integer, intent(in) :: unit
!!      character(len=*), intent(in) :: name
!!      real, intent(in), optional :: rval(:)
!!      integer, intent(in), optional :: ival(:)
!!      character(len=*), intent(in), optional :: cval
!!
!! This form defines global metadata associated with the file as a
!! whole. The attribute is named <name> and can take on a real, integer
!! or character value. <rval> and <ival> can be scalar or 1D arrays.
!!
!!  mpp_write_meta( unit, id, name, rval=rval, pack=pack )
!!  mpp_write_meta( unit, id, name, ival=ival )
!!  mpp_write_meta( unit, id, name, cval=cval )
!!      integer, intent(in) :: unit, id
!!      character(len=*), intent(in) :: name
!!      real, intent(in), optional :: rval(:)
!!      integer, intent(in), optional :: ival(:)
!!      character(len=*), intent(in), optional :: cval
!!
!! This form defines metadata associated with a previously defined
!! axis or field, identified to mpp_write_meta by its unique ID <id>.
!! The attribute is named <name> and can take on a real, integer
!! or character value. <rval> and <ival> can be scalar or 1D arrays.
!! This need not be called for attributes already contained in
!! the type.
!!
!! PACK can take values 1,2,4,8. This only has meaning when writing
!! floating point numbers. The value of PACK defines the number of words
!! written into 8 bytes. For pack=4 and pack=8, an integer value is
!! written: rval is assumed to have been scaled to the appropriate dynamic
!! range.
!! PACK currently only works for netCDF files, and is ignored otherwise.
!!
!!  subroutine mpp_write_meta_axis( unit, axis, name, units, longname, &
!!        cartesian, sense, domain, data )
!!     integer, intent(in) :: unit
!!     type(axistype), intent(inout) :: axis
!!     character(len=*), intent(in) :: name, units, longname
!!     character(len=*), intent(in), optional :: cartesian
!!     integer, intent(in), optional :: sense
!!     type(domain1D), intent(in), optional :: domain
!!     real, intent(in), optional :: data(:)
!!
!! This form defines a time or space axis. Metadata corresponding to the
!! type above are written to the file on <unit>. A unique ID for subsequent
!! references to this axis is returned in axis%id. If the <domain>
!! element is present, this is recognized as a distributed data axis
!! and domain decomposition information is also written if required (the
!! domain decomposition info is required for multi-fileset multi-threaded
!! I/O). If the <datLINK> element is allocated, it is considered to be a
!! space axis, otherwise it is a time axis with an unlimited dimension.
!! Only one time axis is allowed per file.
!! @code{.F90}
!!  subroutine mpp_write_meta_field( unit, field, axes, name, units, longname
!!                                   standard_name, min, max, missing, fill, scale, add, pack)
!!     integer, intent(in) :: unit
!!     type(fieldtype), intent(out) :: field
!!     type(axistype), intent(in) :: axes(:)
!!     character(len=*), intent(in) :: name, units, longname, standard_name
!!     real, intent(in), optional :: min, max, missing, fill, scale, add
!!     integer, intent(in), optional :: pack
!! @endcode
!! This form defines a field. Metadata corresponding to the type
!! above are written to the file on <unit>. A unique ID for subsequent
!! references to this field is returned in field%id. At least one axis
!! must be associated, 0D variables are not considered. mpp_write_meta
!! must previously have been called on all axes associated with this
!! field.
!!
!! The mpp_write_meta package also includes subroutines write_attribute and
!! write_attribute_netcdf, that are private to this module.
  interface mpp_write_meta
     module procedure mpp_write_meta_var
     module procedure mpp_write_meta_scalar_r
     module procedure mpp_write_meta_scalar_i
     module procedure mpp_write_meta_axis_r1d
     module procedure mpp_write_meta_axis_i1d
     module procedure mpp_write_meta_axis_unlimited
     module procedure mpp_write_meta_field
     module procedure mpp_write_meta_global
     module procedure mpp_write_meta_global_scalar_r
     module procedure mpp_write_meta_global_scalar_i
  end interface
 
  interface mpp_copy_meta
     module procedure mpp_copy_meta_axis
     module procedure mpp_copy_meta_field
     module procedure mpp_copy_meta_global
  end interface
 
  interface mpp_modify_meta
!     module procedure mpp_modify_att_meta
     module procedure mpp_modify_field_meta
     module procedure mpp_modify_axis_meta
  end interface
 
! <INTERFACE NAME="mpp_write">
!   <OVERVIEW>
!     Write to an open file.
!   </OVERVIEW>
!   <DESCRIPTION>
!    <TT>mpp_write</TT> is used to write data to the file on an I/O unit
!    using the file parameters supplied by <LINK
!    SRC="#mpp_open"><TT>mpp_open</TT></LINK>. Axis and field definitions must
!    have previously been written to the file using <LINK
!    SRC="#mpp_write_meta"><TT>mpp_write_meta</TT></LINK>.  There are three
!    forms of <TT>mpp_write</TT>, one to write axis data, one to write
!    distributed field data, and one to write non-distributed field
!    data. <I>Distributed</I> data refer to arrays whose two
!    fastest-varying indices are domain-decomposed. Distributed data must
!    be 2D or 3D (in space). Non-distributed data can be 0-3D.
!
!    The <TT>data</TT> argument for distributed data is expected by
!    <TT>mpp_write</TT> to contain data specified on the <I>data</I> domain,
!    and will write the data belonging to the <I>compute</I> domain,
!    fetching or sending data as required by the parallel I/O <LINK
!    SRC="#modes">mode</LINK> specified in the <TT>mpp_open</TT> call. This
!    is consistent with our definition of <LINK
!    SRC="http:mpp_domains.html#domains">domains</LINK>, where all arrays are
!    expected to be dimensioned on the data domain, and all operations
!    performed on the compute domain.
!
!     The type of the <TT>data</TT> argument must be a <I>default
!     real</I>, which can be 4 or 8 byte.
!   </DESCRIPTION>
!  <TEMPLATE>
!    mpp_write( unit, axis )
!  </TEMPLATE>
!  <TEMPLATE>
!    mpp_write( unit, field, data, tstamp )
!  </TEMPLATE>
!  <TEMPLATE>
!    mpp_write( unit, field, domain, data, tstamp )
!  </TEMPLATE>
!  <IN NAME="tstamp">
!    <TT>tstamp</TT> is an optional argument. It is to
!    be omitted if the field was defined not to be a function of time.
!    Results are unpredictable if the argument is supplied for a time-
!    independent field, or omitted for a time-dependent field. Repeated
!    writes of a time-independent field are also not recommended. One
!    time level of one field is written per call. tstamp must be an 8-byte
!    real, even if the default real type is 4-byte.
!  </IN>
!  <NOTE>
!    The type of write performed by <TT>mpp_write</TT> depends on the file
!    characteristics on the I/O unit specified at the <LINK
!    SRC="#mpp_open"><TT>mpp_open</TT></LINK> call. Specifically, the format of
!    the output data (e.g netCDF or IEEE), the <TT>threading</TT> and
!    <TT>fileset</TT> flags, etc., can be changed there, and require no
!    changes to the <TT>mpp_write</TT> calls.
!
!    Packing is currently not implemented for non-netCDF files, and the
!    <TT>pack</TT> attribute is ignored. On netCDF files,
!    <TT>NF_DOUBLE</TT>s (8-byte IEEE floating point numbers) are
!    written for <TT>pack</TT>=1 and <TT>NF_FLOAT</TT>s for
!    <TT>pack</TT>=2. (<TT>pack</TT>=2 gives the customary
!    and default behaviour). We write <TT>NF_SHORT</TT>s (2-byte
!    integers) for <TT>pack=4</TT>, or <TT>NF_BYTE</TT>s
!    (1-byte integers) for <TT>pack=8</TT>. Integer scaling is done
!    using the <TT>scale</TT> and <TT>add</TT> attributes at
!    <TT>pack</TT>=4 or 8, satisfying the relation
!
!    <PRE>
!    data = packed_data*scale + add
!    </PRE>
!
!    <TT>NOTE: mpp_write</TT> does not check to see if the scaled
!    data in fact fits into the dynamic range implied by the specified
!    packing. It is incumbent on the user to supply correct scaling
!    attributes.
!
!    You cannot interleave calls to <TT>mpp_write</TT> and
!    <TT>mpp_write_meta</TT>: the first call to
!    <TT>mpp_write</TT> implies that metadata specification is
!    complete.
! </NOTE>
! </INTERFACE>
 
 
  interface write_record
     module procedure write_record_r8
     module procedure write_record_r4
  end interface
 
  interface mpp_write
     module procedure mpp_write_2ddecomp_r2d_r8
     module procedure mpp_write_2ddecomp_r3d_r8
     module procedure mpp_write_2ddecomp_r4d_r8
     module procedure mpp_write_2ddecomp_r2d_r4
     module procedure mpp_write_2ddecomp_r3d_r4
     module procedure mpp_write_2ddecomp_r4d_r4
     module procedure mpp_write_r0d_r8
     module procedure mpp_write_r1d_r8
     module procedure mpp_write_r2d_r8
     module procedure mpp_write_r3d_r8
     module procedure mpp_write_r4d_r8
     module procedure mpp_write_r0d_r4
     module procedure mpp_write_r1d_r4
     module procedure mpp_write_r2d_r4
     module procedure mpp_write_r3d_r4
     module procedure mpp_write_r4d_r4
     module procedure mpp_write_axis
  end interface
 
 
!***********************************************************************
! <INTERFACE NAME="mpp_write_compressed">
!   <OVERVIEW>
!     Write to an opened, sparse data, compressed file (e.g. land_model)
!   </OVERVIEW>
!   <DESCRIPTION>
!     These routines are similar to mpp_write except that they are
!     designed to handle sparse, compressed vectors of data such
!     as from the land model. Currently, the sparse vector may vary in z.
!     Hence the need for the rank 2 treatment.
!  </DESCRIPTION>
!   <TEMPLATE>
!     call mpp_write(unit, field, domain, data, nelems_io, tstamp, default_data )
!   </TEMPLATE>
!  <IN NAME="unit"></IN>
!  <IN NAME="field"></IN>
!  <IN NAME="domain"></IN>
!  <INOUT NAME="data"></INOUT>
!  <IN NAME="nelems_io">
!    <TT>nelems</TT> is a vector containing the number of elements expected
!    from each member of the io_domain. It MUST have the same order as
!    the io_domain pelist.
!  </IN>
!  <IN NAME="tstamp">
!    <TT>tstamp</TT> is an optional argument. It is to
!    be omitted if the field was defined not to be a function of time.
!    Results are unpredictable if the argument is supplied for a time-
!    independent field, or omitted for a time-dependent field. Repeated
!    writes of a time-independent field are also not recommended. One
!    time level of one field is written per call. tstamp must be an 8-byte
!    real, even if the default real type is 4-byte.
!  </IN>
!  <IN NAME="default_data"></IN>
!  <NOTE>
!     <TT>mpp_write_meta</TT> must be called prior to calling
!     <TT>mpp_write_compressed.</TT>
!     Since in general, the vector is distributed across the io-domain
!     The write expects the io_domain to be defined.
!  </NOTE>
! </INTERFACE>
  interface mpp_write_compressed
     module procedure mpp_write_compressed_r1d_r8
     module procedure mpp_write_compressed_r2d_r8
     module procedure mpp_write_compressed_r3d_r8
     module procedure mpp_write_compressed_r1d_r4
     module procedure mpp_write_compressed_r2d_r4
     module procedure mpp_write_compressed_r3d_r4
  end interface mpp_write_compressed
 
!***********************************************************************
! <INTERFACE NAME="mpp_write_unlimited_axis">
!   <OVERVIEW>
!     Write to an opened file along the unlimited axis (e.g. icebergs)
!   </OVERVIEW>
!   <DESCRIPTION>
!     These routines are similar to mpp_write except that they are
!     designed to handle data written along the unlimited axis that
!     is not time (e.g. icebergs).
!  </DESCRIPTION>
!   <TEMPLATE>
!     call mpp_write(unit, field, domain, data, nelems_io)
!   </TEMPLATE>
!  <IN NAME="unit"></IN>
!  <IN NAME="field"></IN>
!  <IN NAME="domain"></IN>
!  <INOUT NAME="data"></INOUT>
!  <IN NAME="nelems">
!    <TT>nelems</TT> is a vector containing the number of elements expected
!    from each member of the io_domain. It MUST have the same order as
!    the io_domain pelist.
!  </IN>
!  <NOTE>
!     <TT>mpp_write_meta</TT> must be called prior to calling
!     <TT>mpp_write_unlimited_axis.</TT>
!     Since in general, the vector is distributed across the io-domain
!     The write expects the io_domain to be defined.
!  </NOTE>
! </INTERFACE>
  interface mpp_write_unlimited_axis
     module procedure mpp_write_unlimited_axis_r1d
  end interface mpp_write_unlimited_axis
 
 
!***********************************************************************
! <INTERFACE NAME="mpp_def_dim">
!   <OVERVIEW>
!     Define an dimension variable
!   </OVERVIEW>
!   <DESCRIPTION>
!     Similar to the mpp_write_meta routines, but simply defines the
!     a dimension variable with the optional attributes
!  </DESCRIPTION>
!   <TEMPLATE>
!     call mpp_def_dim( unit, name, dsize, longname, data )
!   </TEMPLATE>
!  <IN NAME="unit"></IN>
!  <IN NAME="name"></IN>
!  <IN NAME="dsize"></IN>
!  <IN NAME="data"></INOUT>
! </INTERFACE>
  interface mpp_def_dim
     module procedure mpp_def_dim_nodata
     module procedure mpp_def_dim_int
     module procedure mpp_def_dim_real
  end interface mpp_def_dim
 
!***********************************************************************
!
!            module variables
!
!***********************************************************************
  logical            :: module_is_initialized = .false.
  logical            :: verbose =.false.
  logical            :: debug = .false.
  integer            :: maxunits, unit_begin, unit_end
  integer            :: mpp_io_stack_size=0, mpp_io_stack_hwm=0
  integer            :: varnum=0
  integer            :: pe, npes
  character(len=256) :: text
  integer            :: error
  integer            :: records_per_pe
  integer            :: mpp_read_clock=0, mpp_write_clock=0
  integer            :: mpp_open_clock=0, mpp_close_clock=0
 
 
!initial value of buffer between meta_data and data in .nc file
  integer            :: header_buffer_val = 16384  ! value used in NF__ENDDEF
  logical            :: global_field_on_root_pe = .true.
  logical            :: io_clocks_on = .false.
  integer            :: shuffle = 0
  integer            :: deflate = 0
  integer            :: deflate_level = -1
  logical            :: cf_compliance = .false.
 
  namelist /mpp_io_nml/header_buffer_val, global_field_on_root_pe, io_clocks_on, &
                       shuffle, deflate_level, cf_compliance
 
  real(r8_kind), allocatable :: mpp_io_stack(:)
  type(axistype),save            :: default_axis      !provided to users with default components
  type(fieldtype),save           :: default_field     !provided to users with default components
  type(atttype),save             :: default_att       !provided to users with default components
  type(filetype), allocatable    :: mpp_file(:)
 
  integer :: pack_size ! = 1 when compiling with -r8 and = 2 when compiling with -r4.
 
! Include variable "version" to be written to log file.
#include<file_version.h>
 
!----------
!ug support
public :: mpp_io_unstructured_write
public :: mpp_io_unstructured_read
 
interface mpp_io_unstructured_write
    module procedure mpp_io_unstructured_write_r8_1d
    module procedure mpp_io_unstructured_write_r8_2d
    module procedure mpp_io_unstructured_write_r8_3d
    module procedure mpp_io_unstructured_write_r8_4d
    module procedure mpp_io_unstructured_write_r4_1d
    module procedure mpp_io_unstructured_write_r4_2d
    module procedure mpp_io_unstructured_write_r4_3d
    module procedure mpp_io_unstructured_write_r4_4d
end interface mpp_io_unstructured_write
 
interface mpp_io_unstructured_read
    module procedure mpp_io_unstructured_read_r8_1d
    module procedure mpp_io_unstructured_read_r8_2d
    module procedure mpp_io_unstructured_read_r8_3d
    module procedure mpp_io_unstructured_read_r4_1d
    module procedure mpp_io_unstructured_read_r4_2d
    module procedure mpp_io_unstructured_read_r4_3d
end interface mpp_io_unstructured_read
!----------
 
contains
 
#include <mpp_io_util.inc>
#include <mpp_io_misc.inc>
#include <mpp_io_connect.inc>
#include <mpp_io_read.inc>
#include <mpp_io_write.inc>
 
!----------
!ug support
#include <mpp_io_unstructured_write.inc>
#include <mpp_io_unstructured_read.inc>
!----------
#endif
end module mpp_io_mod
!> @}
! close documentation grouping