Only use Langmuir enhanced entrainment where LaSL has a valid value

Author: qingli411

source/vmix_kpp.F90

@@ -2506,9 +2506,10 @@ subroutine bldepth (CVmix_vars, DBLOC, DBSFC, TRCR, UUU, VVV, UCUR, VCUR,     &
           do i = 1,nx_block
             ic = (j-1)*nx_block + i
             if (kl.le.CVmix_vars(ic)%nlev) then
-              if (IFRAC(i,j,bid) <= 0.05_r8) then
+              if (IFRAC(i,j,bid) <= 0.05_r8 .and. LASL(i,j,bid) > c0 .and.    &
+                  LASL(i,j,bid) <= c10) then
                 ! only use Langmuir enhanced entrainment in ice-free regions
-                ! where ice fraction is less than 5%
+                ! where ice fraction is less than 5% and LaSL has a valid value
                 RI_BULK(i,j,kdn:kdn) = cvmix_kpp_compute_bulk_Richardson(     &
                             zt_cntr = (/zgrid(kl)/)*1e-2_r8,                  &
                             ws_cntr = (/WS(i,j)/)*1e-2_r8,                    &