diff --git a/conf/real-from-d2-ana/simulation.yml b/conf/real-from-d2-ana/simulation.yml
index ed8083f4e068d51e5b7d6e724f5b7a83760ac980..04f953770bd314fdb7428c25c4289453adbb7235 100644
--- a/conf/real-from-d2-ana/simulation.yml
+++ b/conf/real-from-d2-ana/simulation.yml
@@ -33,3 +33,7 @@ simulation:
     parent_folder: /dss/dsskcsfs01/pn34ca/pn34ca-dss-0007/DATA-OP/
 
     
+
+  uncertanty:
+    psp: False
+    mpp: False # must be capitalised
\ No newline at end of file
diff --git a/templates/real-from-d2-ana/prepare_namelist.py b/templates/real-from-d2-ana/prepare_namelist.py
index 059c5d7ce0b038d1fd7d387ef87789392e3bdd34..2eb9e2d4b3de24cca5055f42e9cdeeec16bb2054 100644
--- a/templates/real-from-d2-ana/prepare_namelist.py
+++ b/templates/real-from-d2-ana/prepare_namelist.py
@@ -56,6 +56,23 @@ master_namelist_string = """
 # Compute difference in seconds
 checkpoint_time = int((Chunk_END_DATE - Chunk_START_DATE).total_seconds())
 
+# Turn on or off PSP perturbations
+if %simulation.uncertanty.psp% :
+    inwp_psp = 1
+else:
+    inwp_psp = 0
+
+# Microphysics Parameter Perturbations
+ccn_type = 7
+cloudnue = 1
+
+MPPCOMB = ((7,1), (6, 0), (6, 8), (9, 0), (9,8))
+IBC_MPP_COMBLIST = [0, 1, 4, 4, 0, 3, 4, 1, 2, 0, 2, 0, 1, 3, 1, 3, 2, 4, 2, 3]
+if %simulation.uncertanty.mpp% :
+    ccn_type = MPPCOMB[IBC_MPP_COMBLIST[int(MEMBER[1:])-1]][0]
+    cloudnue = MPPCOMB[IBC_MPP_COMBLIST[int(MEMBER[1:])-1]][1]
+
+         
 # TODO: Is that really necessary?
 # Add 10 minutes to allow the model to write the restarts
 # Chunk_END_DATE = Chunk_END_DATE + timedelta(minutes=10)
@@ -80,14 +97,15 @@ atmosphere_namelist_replacements = {
         "latbc_boundary_grid": "%simulation.lateral_boundary_grid_filename%",
     },
     "nwp_phy_nml": {
+        "inwp_psp" : inwp_psp,
         "psp_rnd_seed": int(MEMBER[1:]),
         #"psp_apply_ddt_core": ".false.", # True if vertical wind perturbations should be applied at the explicit dynamical core timestep
         "inwp_gscp": 4 ,               # 1: default, 2: graupel scheme for convection-permitting scales
     },
     
     "twomom_mcrph_nml": {
-         "ccn_type" : 7,
-         "cloudnue" : 0, 
+         "ccn_type" : ccn_type,
+         "cloudnue" : cloudnue, 
          "rainnue"  : 0,
     },