SnowAge

INTERFACE:

   subroutine SnowAge (c)

DESCRIPTION:

   Updates snow age Based on BATS code.

USES:

     use shr_kind_mod, only: r8 => shr_kind_r8
     use clmtype
     use globals, only: dtime
     use clm_varcon, only : tfrz

ARGUMENTS:

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

CALLED FROM:

REVISION HISTORY:

   Original Code:  Robert Dickinson
   15 September 1999: Yongjiu Dai; Integration of code into CLM
   15 December 1999:  Paul Houser and Jon Radakovich; F90 Revision 
   3/4/02, Peter Thornton: Migrated to new data structures.

LOCAL VARIABLES:

   local pointers to implicit in scalars
     real(r8),pointer:: t_grnd     !ground temperature (Kelvin)
     real(r8),pointer:: h2osno     !snow water (mm H2O)
     real(r8),pointer:: h2osno_old !snow mass for previous time step (kg/m2)
   local pointers to implicit inout scalars
     real(r8),pointer:: snow_age    !non dimensional snow age [-]