diff --git a/models/MOM6/model_mod.f90 b/models/MOM6/model_mod.f90
index 2f6f02a8cd..27aaec37f5 100644
--- a/models/MOM6/model_mod.f90
+++ b/models/MOM6/model_mod.f90
@@ -49,7 +49,7 @@ module model_mod
 
 use obs_kind_mod, only : get_index_for_quantity, QTY_U_CURRENT_COMPONENT, &
                          QTY_V_CURRENT_COMPONENT, QTY_LAYER_THICKNESS, &
-                         QTY_DRY_LAND
+                         QTY_DRY_LAND, QTY_SALINITY
 
 use ensemble_manager_mod, only : ensemble_type
 
@@ -383,6 +383,11 @@ subroutine model_interpolate(state_handle, ens_size, location, qty, expected_obs
 ! expected_obs = bot_val + lev_fract * (top_val - bot_val)
 expected_obs = expected(:,1) + lev_fract(:) * (expected(:,2) - expected(:,1))
 
+if (qty == QTY_SALINITY) then  ! convert from PSU (model) to MSU (obersvation)
+   expected_obs = expected_obs/1000.0_r8
+endif
+
+
 end subroutine model_interpolate
 
 
diff --git a/observations/obs_converters/GTSPP/GTSPP.rst b/observations/obs_converters/GTSPP/GTSPP.rst
index d2b0ea0623..9ce4894c9b 100644
--- a/observations/obs_converters/GTSPP/GTSPP.rst
+++ b/observations/obs_converters/GTSPP/GTSPP.rst
@@ -26,6 +26,13 @@ information (not quality control, but observation instrument error values). Ther
 information encoded in these files, but so far we don't have the key. The quality control values are read and only those
 with a QC of 1 are retained.
 
+.. Note::  
+
+   The GTSPP data is in PSU, the dart observation converter ``gtspp_to_obs`` converts the observations to MSU.
+ 
+   | PSU = g/kg
+   | MSU = PSU/1000 = kg/kg
+
 Programs
 --------
 
diff --git a/observations/obs_converters/WOD/WOD.rst b/observations/obs_converters/WOD/WOD.rst
index c262341e74..ab373bbf61 100644
--- a/observations/obs_converters/WOD/WOD.rst
+++ b/observations/obs_converters/WOD/WOD.rst
@@ -38,6 +38,15 @@ NCAR staff have prepared datasets already converted to DART's obs_seq file
 format for the World Ocean Database 2013 (WOD13) and the World Ocean Database
 2009 (WOD09).
 
+.. Warning::  
+
+   The WOD data is in PSU, the dart observation converter ``wod_to_obs`` converts the observations to MSU.
+ 
+   | PSU = g/kg
+   | MSU = PSU/1000 = kg/kg
+   
+   The WOD observation sequence files availiable from NCAR's RDA are in MSU.
+
 WOD13
 ~~~~~