cam6_4_061: Fix heating depth for gravity wave scheme

doc/ChangeLog

@@ -1,3 +1,12 @@
+One-line Summary: fix heating depth bug for gravity wave parameterization
+
+Purpose of changes (include the issue number and title text for each relevant GitHub issue):
+
+Gravity wave scheme fails to catch the right maximum latent heating rate and convective top from the ZM scheme.
+This PR fixes that isuue.
+(Github issue #1229)
+
+Expect baseline differences for CAM7 and WACCM tests
 ===============================================================
 
 Tag name: cam6_4_060

src/physics/cam/gw_convect.F90

@@ -161,25 +161,28 @@ subroutine gw_beres_src(ncol, band, desc, u, v, &
   do k = pver, 1, -1
      do i = 1, ncol
         if (boti(i) == 0) then
-           ! Detect if we are outside the maximum range (where z = 20 km).
+           ! Detect if we are outside the top of range (where z = 20 km).
            if (zm(i,k) >= 20000._r8) then
               boti(i) = k
               topi(i) = k
            else
               ! First spot where heating rate is positive.
               if (netdt(i,k) > 0.0_r8) boti(i) = k
            end if
-        else if (topi(i) == 0) then
-           ! Detect if we are outside the maximum range (z = 20 km).
-           if (zm(i,k) >= 20000._r8) then
-              topi(i) = k
-           else
-              ! First spot where heating rate is no longer positive.
-              if (.not. (netdt(i,k) > 0.0_r8)) topi(i) = k
-           end if
         end if
      end do
-     ! When all done, exit.
+     ! When all done, exit
+     if (all(boti /= 0)) exit
+  end do
+
+  do k = 1, pver
+     do i = 1, ncol
+        if (topi(i) == 0) then
+                ! First spot where heating rate is positive.
+              if ((netdt(i,k) > 0.0_r8) .AND. (zm(i,k) <= 20000._r8)) topi(i) = k
+        end if
+     end do
+     ! When all done, exit
      if (all(topi /= 0)) exit
   end do