Fixed zisodisp offset value

src/write_global_output.f90

@@ -186,7 +186,7 @@ if (iproc.eq.0) then
    if (params%isobc) then 
      ! write isostasy basal displacement array - dwhipp 11/09 
        write (9) 2**params%levelmax_oct
-       write (9) ((zi%zisodisp(i,j)+surface(surface(is)%nsurface)%sp01,&
+       write (9) ((zi%zisodisp(i,j)+surface(osolve%nlsf)%sp01,&
                  j=1,2**params%levelmax_oct+1),i=1,2**params%levelmax_oct+1) 
    end if