FrictionVelocity

INTERFACE:

   subroutine FrictionVelocity (displa, z0m,   z0h,   z0q,   obu, &
                                iter, ur, um, ustar, temp1,  &
                                temp2, forc_hgt, forc_hgt_u, forc_hgt_t, forc_hgt_q, &
                                u10, fm, fv)

DESCRIPTION:

   Calculation of the friction velocity, relation for potential 
   temperature and humidity profiles of surface boundary layer. 
   The scheme is based on the work of Zeng et al. (1998): 
   Intercomparison of bulk aerodynamic algorithms for the computation 
   of sea surface fluxes using TOGA CORE and TAO data. J. Climate, 
   Vol. 11, 2628-2644.

USES:

     use clm_varcon, only : vkc

ARGUMENTS:

     implicit none
     real(r8), intent(in) :: displa     !displacement height [m]
     real(r8), intent(in) :: z0m        !roughness length, momentum [m]
     real(r8), intent(in) :: z0h        !roughness length, sensible heat [m]
     real(r8), intent(in) :: z0q        !roughness length, latent heat [m]
     real(r8), intent(in) :: obu        !monin-obukhov length (m)
     real(r8), intent(in) :: um         !wind speed including the stablity effect [m/s]
     real(r8), intent(in) :: ur   
     integer , intent(in) :: iter       !iteration number
     real(r8), intent(in) :: forc_hgt   !atmospheric reference height (m)
     real(r8), intent(in) :: forc_hgt_u !observational height of wind [m]
     real(r8), intent(in) :: forc_hgt_t !observational height of temperature [m]
     real(r8), intent(in) :: forc_hgt_q !observational height of humidity [m]
     real(r8), intent(out) :: ustar     !friction velocity [m/s]
     real(r8), intent(out) :: temp1     !relation for potential temperature profile
     real(r8), intent(out) :: temp2     !relation for specific humidity profile
     real(r8), intent(out) :: u10       !10-m wind (m/s) (for dust model)
     real(r8), intent(out) :: fv	       !friction velocity (m/s) (for dust model)
     real(r8), intent(inout) :: fm      !needed for BGC only to diagnose 10m wind speed

CALLED FROM:

REVISION HISTORY:

   15 September 1999: Yongjiu Dai; Initial code
   15 December 1999:  Paul Houser and Jon Radakovich; F90 Revision 
   12/19/01, Peter Thornton
   Added arguments to eliminate passing clm derived type into this function.
   Created by Mariana Vertenstein