Merge branch 'cbegeman/ocn-fix-temperature-tendency' (PR #6976)

Bugfix for frazil ice temperature tendency

Add temperature tendency due to mixing of frazil meltwater with
seawater. When frazil ice melts in MPAS-Ocean it is a freshwater volume
flux (not a virtual flux). As such, there should be two components to
the temperature tendency due to frazil melt, a latent heat flux and a
flux associated with the mixing of water at the freezing point with the
ambient seawater. The latter was not included (a bug).

Fixes #6975
[non-BFB] for all configurations with mpas-ocean

components/mpas-ocean/src/shared/mpas_ocn_frazil_forcing.F

@@ -605,6 +605,10 @@ subroutine ocn_frazil_forcing_build_arrays(domain, meshPool, forcingPool, stateP
                                                  * config_frazil_ice_density ) / (config_specific_heat_sea_water * rho_sw) &
                                                  / dt
 
+              ! ocean fluid temperature is modified due to mixing of existing water with meltwater at the freezing point
+              frazilTemperatureTendency(k,iCell) = frazilTemperatureTendency(k,iCell) + &
+                   meltedFrazilIceThickness * oceanFreezingTemperature / dt
+
               ! keep track of new frazil ice
               sumNewThicknessWeightedSaltContent = max(0.0_RKIND,sumNewThicknessWeightedSaltContent - meltedThicknessWeightedSaltContent)
               sumNewFrazilIceThickness = max(0.0_RKIND,sumNewFrazilIceThickness - meltedFrazilIceThickness)