Changeset 4338 for palm

Timestamp:

Dec 13, 2019 1:23:23 PM (5 years ago)

Author:

suehring

Message:

To avoid divisions by zero, add security factor in calculation of roughness length over water surfaces.

File:

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

palm/trunk/SOURCE/land_surface_model_mod.f90

@@ -25 +25 @@
 ! -----------------
 ! $Id$
+! To avoid divisions by zero, add security factor in calculation of roughness 
+! length over water surfaces.
+! 
+! 4321 2019-12-04 10:26:38Z pavelkrc
 ! Initialization of relative surface fractions revised
 ! 
@@ -7230 +7234 @@
 !--          wind speed, the sea surface becomes aerodynamically smooth and
 !--          the roughness scales with the viscosity. At high wind speed, the
-!--          Charnock relation is used.
+!--          Charnock relation is used. Add a security factor of 1E-8 to avoid
+!--          divisions by zero.
              surf_lsm_h%z0(m)  = ( 0.11_wp * molecular_viscosity /             &
-                                 surf_lsm_h%us(m) )                            &
+                                 ( surf_lsm_h%us(m) + 1E-8_wp ) )              &
                                + ( alpha_ch * surf_lsm_h%us(m)**2 / g )
 
              surf_lsm_h%z0h(m) = 0.40_wp * molecular_viscosity /               &
-                                 surf_lsm_h%us(m)
+                                 ( surf_lsm_h%us(m) + 1E-8_wp )
              surf_lsm_h%z0q(m) = 0.62_wp * molecular_viscosity /               &
-                                 surf_lsm_h%us(m)
+                                 ( surf_lsm_h%us(m) + 1E-8_wp )