Changeset 3143 for palm/trunk/SOURCE/land_surface_model_mod.f90

Timestamp:

Jul 17, 2018 10:14:30 PM (6 years ago)

Author:

maronga

Message:

modified calculation of surface resistance in land surface scheme

File:

• palm/trunk/SOURCE/land_surface_model_mod.f90 (modified) (2 diffs)

palm/trunk/SOURCE/land_surface_model_mod.f90

@@ -25 +25 @@
 ! -----------------
 ! $Id$
+! Modified calculation of the surface resistance r_s
+! 
+! 3142 2018-07-17 15:27:45Z suehring
 ! Minor bugfix for last commit.
 ! 
@@ -2151 +2154 @@
 
 !
-!--    Calculate the true surface resistance
+!--    Calculate the true surface resistance. ABS is used here to avoid negative
+!--    values that can occur for very small fluxes due to the artifical addition
+!--    of 1.0E-20.
        IF ( .NOT.  humidity )  THEN
           surf%r_s(m) = 1.0E10_wp
        ELSE
-          surf%r_s(m) = - rho_lv * ( surf%qv1(m) - q_s + dq_s_dt               &
-                          * surf_t_surface%var_1d(m) - dq_s_dt *               &
-                            surf_t_surface_p%var_1d(m) ) /                     &
-                            (surf%qsws(m) + 1.0E-20)  - surf%r_a(m)
+          surf%r_s(m) = ABS(rho_lv / (f_qsws + 1.0E-20_wp) - surf%r_a(m))
        ENDIF
-!
-!--    Limit resistance resistance
-       surf%r_s(m) = MAX( surf%r_s(m), 1.0_wp )
 !
 !--    Calculate change in liquid water reservoir due to dew fall or