#include <misc.h>#include <preproc.h>subroutine Combo     (dz,    wliq,  wice,  t, dz2, &                      wliq2, wice2, t2     ) !-----------------------------------------------------------------------!!  CLMCLMCLMCLMCLMCLMCLMCLMCLMCL  A community developed and sponsored, freely!  L                           M  available land surface process model.!  M --COMMUNITY LAND MODEL--  C!  C                           L!  LMCLMCLMCLMCLMCLMCLMCLMCLMCLM!!-----------------------------------------------------------------------! Purpose:! Combines two elements and returns the following combined! variables: dz, t, wliq, wice. !! Method:! The combined temperature is based on the equation:! the sum of the enthalpies of the two elements =  ! that of the combined element.!! Author:! 15 September 1999: Yongjiu Dai; Initial code! 15 December 1999:  Paul Houser and Jon Radakovich; F90 Revision ! April 2002: Vertenstein/Oleson/Levis; Final form!!-----------------------------------------------------------------------! $Id: Combo.F90,v 1.1.10.2 2002/04/27 15:38:37 erik Exp $!-----------------------------------------------------------------------  use precision  use clm_varcon,  only : cpice, cpliq, tfrz, hfus           implicit none!----Arguments----------------------------------------------------------  real(r8), intent(in) :: dz2   ! nodal thickness of 2 elements being combined [m]  real(r8), intent(in) :: wliq2 ! liquid water of element 2 [kg/m2]  real(r8), intent(in) :: wice2 ! ice of element 2 [kg/m2]  real(r8), intent(in) :: t2    ! nodal temperature of element 2 [K]  real(r8), intent(inout) :: dz   ! nodal thickness of 1 element being combined [m]  real(r8), intent(inout) :: wliq ! liquid water of element 1 [kg/m2]  real(r8), intent(inout) :: wice ! ice of element 1 [kg/m2]  real(r8), intent(inout) :: t    ! nodal temperature of elment 1 [K]!----Local Variables----------------------------------------------------  real(r8) dzc   ! Total thickness of nodes 1 and 2 (dzc=dz+dz2). [m]  real(r8) wliqc ! Combined liquid water [kg/m2]  real(r8) wicec ! Combined ice [kg/m2]  real(r8) tc    ! Combined node temperature [K]  real(r8) h     ! enthalpy of element 1 [J/m2]  real(r8) h2    ! enthalpy of element 2 [J/m2]  real(r8) hc    ! temporary variable [-]!----End Variable List--------------------------------------------------  dzc = dz+dz2  wicec = (wice+wice2)  wliqc = (wliq+wliq2)  h =(cpice*wice+cpliq*wliq)* &       (t-tfrz)+hfus*wliq  h2=(cpice*wice2+cpliq*wliq2)* &       (t2-tfrz)+hfus*wliq2  hc = h + h2  if(hc < 0.)then     tc = tfrz + hc/(cpice* &          wicec+cpliq*wliqc)  else if(hc.le.hfus*wliqc)then     tc = tfrz  else     tc = tfrz + (hc - hfus*wliqc)/ &          (cpice*wicec+cpliq*wliqc)  endif  dz = dzc  wice = wicec   wliq = wliqc  t = tcend subroutine Combo