SnowCompaction

INTERFACE:

   subroutine SnowCompaction(lbc, ubc, num_snowc, filter_snowc)

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 clm_time_manager, only : get_step_size
     use clm_varcon  , only : denice, denh2o, tfrz, istice_mec

ARGUMENTS:

     implicit none
     integer, intent(in) :: lbc, ubc                ! column bounds
     integer, intent(in) :: num_snowc               ! number of column snow points in column filter
     integer, intent(in) :: filter_snowc(ubc-lbc+1) ! column filter for snow points

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
   2/29/08, David Lawrence: Revised snow overburden to be include 0.5 weight of current layer

LOCAL VARIABLES:

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