Add in area correction to mizuRoute

[ekluzek]

With the latest version of CTSM we have area correction added into CTSM, MOSART and RTM. This is multiplying fields by the ratio of what the model things the area is divided by the area as defined by the mesh file.

Here's an example section added to the end of realize fields for RTM:

+    ! Determine areas for regridding
+    call ESMF_MeshGet(Emesh, numOwnedElements=numOwnedElements, rc=rc)
+    if (chkerr(rc,__LINE__,u_FILE_u)) return
+    call ESMF_StateGet(exportState, itemName=trim(fldsFrRof(2)%stdname), field=lfield, rc=rc)
+    if (ChkErr(rc,__LINE__,u_FILE_u)) return
+    call ESMF_FieldRegridGetArea(lfield, rc=rc)
+    if (chkerr(rc,__LINE__,u_FILE_u)) return
+    call ESMF_FieldGet(lfield, farrayPtr=dataptr, rc=rc)
+    if (chkerr(rc,__LINE__,u_FILE_u)) return
+    allocate(mesh_areas(numOwnedElements))
+    mesh_areas(:) = dataptr(:)
+
+    ! Determine flux correction factors (module variables)
+    allocate(model_areas(numOwnedElements))
+    allocate (mod2med_areacor(numOwnedElements))
+    allocate (med2mod_areacor(numOwnedElements))
+    n = 0
+    do g = runoff%begr,runoff%endr
+       n = n + 1
+       model_areas(n) = runoff%area(g)*1.0e-6_r8/(re*re)
+       mod2med_areacor(n) = model_areas(n) / mesh_areas(n)
+       med2mod_areacor(n) = mesh_areas(n) / mod2med_areacor(n)
+    end do
+    deallocate(model_areas)
+    deallocate(mesh_areas)
+
+    min_mod2med_areacor = minval(mod2med_areacor)
+    max_mod2med_areacor = maxval(mod2med_areacor)
+    min_med2mod_areacor = minval(med2mod_areacor)
+    max_med2mod_areacor = maxval(med2mod_areacor)
+    call shr_mpi_max(max_mod2med_areacor, max_mod2med_areacor_glob, mpicom_rof)
+    call shr_mpi_min(min_mod2med_areacor, min_mod2med_areacor_glob, mpicom_rof)
+    call shr_mpi_max(max_med2mod_areacor, max_med2mod_areacor_glob, mpicom_rof)
+    call shr_mpi_min(min_med2mod_areacor, min_med2mod_areacor_glob, mpicom_rof)
+
+    if (masterproc) then
+       write(iulog,'(2A,2g23.15,A )') trim(subname),' :  min_mod2med_areacor, max_mod2med_areacor ',&
+            min_mod2med_areacor_glob, max_mod2med_areacor_glob, 'RTM'
+       write(iulog,'(2A,2g23.15,A )') trim(subname),' :  min_med2mod_areacor, max_med2mod_areacor ',&
+            min_med2mod_areacor_glob, max_med2mod_areacor_glob, 'RTM'
+    end if
+

Then import_fields adds an extra argument for each field...

     allocate(temp(begr:endr,3))
 
-    call state_getimport(importState, 'Flrl_rofsur', begr, endr, output=temp(:,1), rc=rc)
+    call state_getimport(importState, 'Flrl_rofsur', begr, endr, output=temp(:,1), do_area_correction=.true., rc=rc)
     if (ChkErr(rc,__LINE__,u_FILE_u)) return

Which then does this...

+    ! determine output array
+    if (do_area_correction) then
+       fldptr(:) = fldptr(:) * med2mod_areacor(:)
     end if
+    do g = begr,endr
+       output(g) = fldptr(g-begr+1)
+    end do
+
+    ! check for nans
+    call check_for_nans(fldptr, trim(fldname), begr)

Similar stuff for export state...

[ekluzek]

I think in mizuRoute we may be OK in assuming this ratio is zero, since mizuRoute doesn't explicitly handle area.

[ekluzek]

We don't think this is much of a problem in other ROF components.