program_csm (Source File: program_csm.F90)

INTERFACE:

 PROGRAM program_csm

DESCRIPTION:

   Driver for CLM as the land component of CCSM.
   This program is the driver for CLM to work as the land component of
   CCSM.  The flux coupler will provide all the appropriate atmospheric
   forcing for the land model to run.
   o the land surface model returns to the CCSM flux coupler surface
     fluxes, temperatures, and albedos for only the land points on the
     [lsmlon x lsmlat] grid
   o the land surface model uses its own surface type data set. because
     it processes only land points, this data set must correctly define
     what points are land and what are not land
   o the land surface model uses its own grid dimensions (lsmlon and
     lsmlat). currently these must equal lsmlon and lsmlat so that there
     is a direct correspondence between the atmosphere and land grids
   o the zenith angle calculation is calculated for the
     NEXT time step rather than the current time step. make sure
     the calendar day is for the NEXT time step. make sure the
     solar declination calculation is the same as in the
     atmospheric model but for the NEXT time step. make sure the
     calendar day is for greenwich time (see next comment).
   o subroutine calendr: this generates a julian day (with fraction)
     based on the time step, which is used to calculate the solar
     zenith angle. this time must be at the greenwich meridian to
     get the correct zenith angle. also, output from this subroutine
     is used to calculate the month (1, ..., 12), day (1, ..., 31),
     and year (00, ...) of the simulation.
   o the land surface model calculates its own net solar radiation and
     net longwave radiation at the surface. the net longwave radiation
     at the surface will differ somewhat from that calculated from the
     CCSM flux coupler because the cpl model will use the upward
     longwave flux (or radiative temperature) from the previous time
     step whereas the land surface model uses the flux for the current
     time step. the net solar radiation should equal that calculated
     from the flux coupler. if not, there is a problem.

USES:

   use shr_kind_mod, only: r8 => shr_kind_r8
   use clm_varpar         !parameters
   use clm_varctl         !run control variables
   use shr_orb_mod        !orbital parameters and routines
   use shr_msg_mod        !csm message passing routines and variables
 #if (defined SPMD)
   use spmdMod      , only : masterproc, iam, spmd_init, mpicom
 #else
   use spmdMod      , only : masterproc, iam
 #endif
   use initializeMod, only : initialize
   use clm_csmMod   , only : csmstop_now, csm_setup, csm_shutdown
   use time_manager , only : advance_timestep, get_nstep

ARGUMENTS:

     implicit none
 #include "gpt.inc"

REVISION HISTORY:

   Created by Mariana Vertenstein