From 21d1038b65d14f9337d60f4412fc0fed27d667aa Mon Sep 17 00:00:00 2001
From: alperaltuntas <alperaltuntas@gmail.com>
Date: Thu, 31 May 2018 18:51:36 -0600
Subject: [PATCH] Check if Kv is associated before updating it

---
 .../vertical/MOM_tidal_mixing.F90             | 23 +++++++++----------
 1 file changed, 11 insertions(+), 12 deletions(-)

diff --git a/src/parameterizations/vertical/MOM_tidal_mixing.F90 b/src/parameterizations/vertical/MOM_tidal_mixing.F90
index b659e9149a..226f7c4918 100644
--- a/src/parameterizations/vertical/MOM_tidal_mixing.F90
+++ b/src/parameterizations/vertical/MOM_tidal_mixing.F90
@@ -754,9 +754,11 @@ subroutine calculate_CVMix_tidal(h, j, G, GV, CS, N2_int, Kd, Kv)
       enddo
 
       ! Update viscosity
-      do k=1,G%ke+1
-        Kv(i,j,k) = Kv(i,j,k) + Kv_tidal(k)
-      enddo
+      if (associated(Kv)) then
+        do k=1,G%ke+1
+          Kv(i,j,k) = Kv(i,j,k) + Kv_tidal(k)
+        enddo
+      endif
 
       ! diagnostics
       if (associated(dd%Kd_itidal)) then
@@ -851,9 +853,11 @@ subroutine calculate_CVMix_tidal(h, j, G, GV, CS, N2_int, Kd, Kv)
       enddo
 
       ! Update viscosity
-      do k=1,G%ke+1
-        Kv(i,j,k) = Kv(i,j,k) + Kv_tidal(k)
-      enddo
+      if (associated(Kv)) then
+        do k=1,G%ke+1
+          Kv(i,j,k) = Kv(i,j,k) + Kv_tidal(k)
+        enddo
+      endif
 
       ! diagnostics
       if (associated(dd%Kd_itidal)) then
@@ -903,12 +907,7 @@ subroutine add_int_tide_diffusivity(h, N2_bot, j, TKE_to_Kd, max_TKE, G, GV, CS,
   real, dimension(SZI_(G),SZJ_(G),SZK_(G)+1), optional, intent(inout) :: Kd_int
   real,                                       intent(inout) :: Kd_max
 
-  ! This subroutine adds the effect of internal-tide-driven mixing to the layer diffusivities.
-  ! The mechanisms considered are (1) local dissipation of internal waves generated by the
-  ! barotropic flow ("itidal"), (2) local dissipation of internal waves generated by the propagating
-  ! low modes (rays) of the internal tide ("lowmode"), and (3) local dissipation of internal lee waves.
-  ! Will eventually need to add diffusivity due to other wave-breaking processes (e.g. Bottom friction,
-  ! Froude-number-depending breaking, PSI, etc.).
+  ! local
 
   real, dimension(SZI_(G)) :: &
     htot,             & ! total thickness above or below a layer, or the