bring this in just for integration work

components/homme/src/share/vertremap_base.F90

@@ -104,7 +104,7 @@ subroutine remap1(Qdp,nx,qsize,dp1,dp2)
      call remap1_nofilter(qdp,nx,qsize,dp1,dp2)
      return
   endif
-  if (vert_remap_q_alg == 1 .or. vert_remap_q_alg == 2 .or. vert_remap_q_alg == 3) then
+  if (vert_remap_q_alg == 1 .or. vert_remap_q_alg == 2 .or. vert_remap_q_alg == 3 .or. vert_remap_q_alg == 10) then
      call remap_Q_ppm(qdp,nx,qsize,dp1,dp2)
      return
   endif
@@ -616,6 +616,11 @@ subroutine remap_Q_ppm(Qdp,nx,qsize,dp1,dp2)
              ao(nlev+k) = ao(nlev+1-k)
           endif
         enddo
+        if (vert_remap_q_alg == 10) then
+                call linextrap(dpo(2), dpo(1), dpo(0), dpo(-1), ao(2), ao(1),ao(0), ao(-1))
+                call linextrap(dpo(nlev-1), dpo(nlev), dpo(nlev+1), dpo(nlev+2),&
+                     ao(nlev-1), ao(nlev), ao(nlev+1), ao(nlev+2))
+        end if
         !Compute monotonic and conservative PPM reconstruction over every cell
         coefs(:,:) = compute_ppm( ao , ppmdx )
         !Compute tracer values on the new grid by integrating from the old cell bottom to the new
@@ -765,6 +770,27 @@ subroutine binary_search(pio, pivot, k)
     k = lo
   end subroutine binary_search
 
+
+  subroutine linextrap(dx1,dx2,dx3,dx4,y1,y2,y3,y4)
+    real(kind=real_kind), intent(in) :: dx1,dx2,dx3,dx4,y1,y2
+    real(kind=real_kind), intent(out) :: y3,y4
+
+    real(kind=real_kind), parameter :: half = 0.5d0
+
+    real(kind=real_kind) :: x1,x2,x3,x4,a
+
+    x1 = half*dx1
+    x2 = x1 + half*(dx1 + dx2)
+    x3 = x2 + half*(dx2 + dx3)
+    x4 = x3 + half*(dx3 + dx4)
+
+    a  = (x3-x1)/(x2-x1)
+    y3 = (1-a)*y1 + a*y2
+    a  = (x4-x1)/(x2-x1)
+    y4 = (1-a)*y1 + a*y2    
+  end subroutine linextrap
+
+
 end module vertremap_base