SnowCompaction

INTERFACE:

   subroutine SnowCompaction (c)

DESCRIPTION:

   Determine the change in snow layer thickness due to compaction and 
   settling. 
   Three metamorphisms of changing snow characteristics are implemented, 
   i.e., destructive, overburden, and melt. The treatments of the former 
   two are from SNTHERM.89 and SNTHERM.99 (1991, 1999). The contribution 
   due to melt metamorphism is simply taken as a ratio of snow ice 
   fraction after the melting versus before the melting.

USES:

     use clmtype
     use globals, only: dtime
     use clm_varcon, only : denice, denh2o, tfrz

ARGUMENTS:

     implicit none
     type (column_type),target,intent(inout):: c		!column derived type

CALLED FROM:

   subroutine Hydrology2 in module Hydrology2Mod

REVISION HISTORY:

   15 September 1999: Yongjiu Dai; Initial code
   15 December 1999:  Paul Houser and Jon Radakovich; F90 Revision 
   2/28/02, Peter Thornton: Migrated to new data structures

LOCAL VARIABLES:

   local pointers to implicit in scalars
     integer,pointer:: snl   !number of snow layers
   local pointers to implicit in arrays
     integer,dimension(:),pointer:: imelt        !flag for melting (=1), freezing (=2), Not=0
     real(r8),dimension(:),pointer:: frac_iceold  !fraction of ice relative to the tot water
     real(r8),dimension(:),pointer:: t_soisno     !soil temperature (Kelvin)
     real(r8),dimension(:),pointer:: h2osoi_ice   !ice lens (kg/m2)
     real(r8),dimension(:),pointer:: h2osoi_liq   !liquid water (kg/m2)
   local pointers to implicit inout arrays
     real(r8),dimension(:),pointer:: dz           !layer depth (m)