Fixes latent heat from fprec and frunoff

This patch fixes a sign bug, in both MCT and NUOPC, when accounting for the latent heat from fprec and frunnoff. Following MOM6's definition, both fprec and frunoff are > 0 into the ocean. Therefore, the latent heat associated with these terms should be negative.
NOAA-GFDL · Jan 22, 2021 · e7d0976 · e7d0976
1 parent 66ec49b
commit e7d0976
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Showing 2 changed files with 12 additions and 10 deletions.
diff --git a/config_src/mct_driver/mom_surface_forcing_mct.F90 b/config_src/mct_driver/mom_surface_forcing_mct.F90
@@ -486,17 +486,17 @@ subroutine convert_IOB_to_fluxes(IOB, fluxes, index_bounds, Time, valid_time, G,
 
     ! latent heat flux (W/m^2)
     fluxes%latent(i,j) = 0.0
-    ! contribution from frozen ppt
+    ! contribution from frozen ppt (notice minus sign since fprec is positive into the ocean)
     if (associated(IOB%fprec)) then
-      fluxes%latent(i,j)              = fluxes%latent(i,j) + &
+      fluxes%latent(i,j)              = fluxes%latent(i,j) - &
           IOB%fprec(i-i0,j-j0)*US%W_m2_to_QRZ_T*CS%latent_heat_fusion
-      fluxes%latent_fprec_diag(i,j)   = G%mask2dT(i,j) * IOB%fprec(i-i0,j-j0)*US%W_m2_to_QRZ_T*CS%latent_heat_fusion
+      fluxes%latent_fprec_diag(i,j)   = - G%mask2dT(i,j) * IOB%fprec(i-i0,j-j0)*US%W_m2_to_QRZ_T*CS%latent_heat_fusion
     endif
-    ! contribution from frozen runoff
+    ! contribution from frozen runoff (notice minus sign since rofi_flux is positive into the ocean)
     if (associated(fluxes%frunoff)) then
-      fluxes%latent(i,j)              = fluxes%latent(i,j) + &
+      fluxes%latent(i,j)              = fluxes%latent(i,j) - &
           IOB%rofi_flux(i-i0,j-j0)*US%W_m2_to_QRZ_T*CS%latent_heat_fusion
-      fluxes%latent_frunoff_diag(i,j) = G%mask2dT(i,j) * IOB%rofi_flux(i-i0,j-j0)*US%W_m2_to_QRZ_T*CS%latent_heat_fusion
+      fluxes%latent_frunoff_diag(i,j) = - G%mask2dT(i,j) * IOB%rofi_flux(i-i0,j-j0)*US%W_m2_to_QRZ_T*CS%latent_heat_fusion
     endif
     ! contribution from evaporation
     if (associated(IOB%q_flux)) then

diff --git a/config_src/nuopc_driver/mom_surface_forcing_nuopc.F90 b/config_src/nuopc_driver/mom_surface_forcing_nuopc.F90
@@ -497,15 +497,17 @@ subroutine convert_IOB_to_fluxes(IOB, fluxes, index_bounds, Time, valid_time, G,
          fluxes%seaice_melt(i,j) = kg_m2_s_conversion * G%mask2dT(i,j) * IOB%seaice_melt(i-i0,j-j0)
 
     fluxes%latent(i,j) = 0.0
+    ! notice minus sign since fprec is positive into the ocean
     if (associated(IOB%fprec)) then
-       fluxes%latent(i,j)            = fluxes%latent(i,j) + &
+       fluxes%latent(i,j)            = fluxes%latent(i,j) - &
            IOB%fprec(i-i0,j-j0)*US%W_m2_to_QRZ_T*CS%latent_heat_fusion
-       fluxes%latent_fprec_diag(i,j) = G%mask2dT(i,j) * IOB%fprec(i-i0,j-j0)*US%W_m2_to_QRZ_T*CS%latent_heat_fusion
+       fluxes%latent_fprec_diag(i,j) = - G%mask2dT(i,j) * IOB%fprec(i-i0,j-j0)*US%W_m2_to_QRZ_T*CS%latent_heat_fusion
     endif
+    ! notice minus sign since frunoff is positive into the ocean
     if (associated(IOB%frunoff)) then
-       fluxes%latent(i,j)              = fluxes%latent(i,j) + &
+       fluxes%latent(i,j)              = fluxes%latent(i,j) - &
            IOB%frunoff(i-i0,j-j0) * US%W_m2_to_QRZ_T * CS%latent_heat_fusion
-       fluxes%latent_frunoff_diag(i,j) = G%mask2dT(i,j) * &
+       fluxes%latent_frunoff_diag(i,j) = - G%mask2dT(i,j) * &
            IOB%frunoff(i-i0,j-j0) * US%W_m2_to_QRZ_T * CS%latent_heat_fusion
     endif
     if (associated(IOB%q_flux)) then