Index: trunk/LMDZ.PLUTO/libf/phypluto/calc_cpp_mugaz.F90
===================================================================
--- trunk/LMDZ.PLUTO/libf/phypluto/calc_cpp_mugaz.F90	(revision 3668)
+++ trunk/LMDZ.PLUTO/libf/phypluto/calc_cpp_mugaz.F90	(revision 3669)
@@ -63,7 +63,9 @@
                mugaz_c = mugaz_c + 30.07*gfrac(igas)
             elseif(igas.eq.igas_C2H2)then
-               ! C2H2 http://encyclopedia.airliquide.com/Encyclopedia.asp?GasID=1
+               ! C2H2 https://encyclopedia.airliquide.com/fr/acetylene
                mugaz_c = mugaz_c + 26.04*gfrac(igas)
             ! GG MODIF JAN2019
+            elseif(igas.eq.igas_C2H4)then
+               mugaz_c = mugaz_c + 28.054*gfrac(igas)
             elseif(igas.eq.igas_CO)then
                mugaz_c = mugaz_c + 28.01*gfrac(igas)
@@ -91,11 +93,11 @@
             ! ignore variable gas in cpp calculation
          else
-            ! all values at 300 K from Engineering Toolbox
+            ! values at minimum temperature from Engineering Toolbox
+            ! (better for Pluto)
             if(igas.eq.igas_CO2)then
-               !cpp_c   = cpp_c   + 0.744*gfrac(igas) ! @ ~210 K (better for
-               !Mars conditions)
-               cpp_c   = cpp_c   + 0.846*gfrac(igas)*44.01/mugaz_c
+            ! https://www.engineeringtoolbox.com/carbon-dioxide-d_974.html
+               cpp_c   = cpp_c   + 0.709*gfrac(igas)*44.01/mugaz_c
             elseif(igas.eq.igas_N2)then
-               cpp_c   = cpp_c   + 1.040*gfrac(igas)*28.01/mugaz_c
+               cpp_c   = cpp_c   + 1.039*gfrac(igas)*28.01/mugaz_c
             elseif(igas.eq.igas_H2)then
                cpp_c   = cpp_c   + 14.31*gfrac(igas)*2.01/mugaz_c
@@ -109,19 +111,21 @@
                cpp_c   = cpp_c   + 1.003*gfrac(igas)*34.08/mugaz_c ! from wikipedia...
             elseif(igas.eq.igas_CH4)then
-               cpp_c   = cpp_c   + 2.226*gfrac(igas)*16.04/mugaz_c
+               cpp_c   = cpp_c   + 2.087*gfrac(igas)*16.04/mugaz_c
             elseif(igas.eq.igas_NH3)then
                cpp_c   = cpp_c   + 2.175*gfrac(igas)*17.03/mugaz_c
                print*,'WARNING, cpp for NH3 may be for liquid'
             elseif(igas.eq.igas_C2H6)then
-               ! C2H6
                ! http://encyclopedia.airliquide.com/Encyclopedia.asp?GasID=28
-               cpp_c   = cpp_c   + 1.763*gfrac(igas)*30.07/mugaz_c
+               cpp_c   = cpp_c   + 1.535*gfrac(igas)*30.07/mugaz_c
             elseif(igas.eq.igas_C2H2)then
-               ! C2H2
-               ! http://encyclopedia.airliquide.com/Encyclopedia.asp?GasID=1
+               ! https://encyclopedia.airliquide.com/fr/acetylene
                cpp_c   = cpp_c   + 1.575*gfrac(igas)*26.04/mugaz_c
             !!!!! MODIF GG JAN 2019  (check source values !!)
+            elseif(igas.eq.igas_C2H4)then
+               ! https://www.engineeringtoolbox.com/ethylene-ethene-C2H4-properties-d_2104.html
+               cpp_c   = cpp_c   + 1.53*gfrac(igas)*28.054/mugaz_c
+            !!!!! MODIF GG JAN 2019  (check source values !!)
             elseif(igas.eq.igas_CO)then
-               cpp_c   = cpp_c   + 1.0425*gfrac(igas)*28.01/mugaz_c
+               cpp_c   = cpp_c   + 1.039*gfrac(igas)*28.01/mugaz_c
             elseif(igas.eq.igas_OCS)then
                cpp_c   = cpp_c   + 0.6909*gfrac(igas)*60.07/mugaz_c
Index: trunk/LMDZ.PLUTO/libf/phypluto/gases_h.F90
===================================================================
--- trunk/LMDZ.PLUTO/libf/phypluto/gases_h.F90	(revision 3668)
+++ trunk/LMDZ.PLUTO/libf/phypluto/gases_h.F90	(revision 3669)
@@ -5,5 +5,5 @@
 !======================================================================C
 !
-!     gases_h    
+!     gases_h
 !
 !     A F90-allocatable version for gases.h -- AS 12/2011
@@ -30,12 +30,13 @@
       integer :: igas_NH3
       integer :: igas_C2H2
+      integer :: igas_C2H4
       integer :: igas_C2H6
 !! GG MODIF Jan 2019
       integer :: igas_OCS
       integer :: igas_HCl
-      integer :: igas_HF            
+      integer :: igas_HF
 !!$OMP THREADPRIVATE(ngasmx,vgas,gnom,gfrac,&
 !	!$OMP igas_H2,igas_He,igas_H2O,igas_N2,igas_CO,igas_N2,&
-!	!$OMP igas_O2,igas_SO2,igas_H2S,igas_CH4,igas_NH3,igas_C2H2,igas_C2H6)
+!	!$OMP igas_O2,igas_SO2,igas_H2S,igas_CH4,igas_NH3,igas_C2H2,igas_C2H4,igas_C2H6)
 ! The saved variables here are not OMP THREADPRIVATE because loaded by
 ! the OMP master only (see su_gases.F90) and thus shared by all threads
Index: trunk/LMDZ.PLUTO/libf/phypluto/su_gases.F90
===================================================================
--- trunk/LMDZ.PLUTO/libf/phypluto/su_gases.F90	(revision 3668)
+++ trunk/LMDZ.PLUTO/libf/phypluto/su_gases.F90	(revision 3669)
@@ -8,14 +8,14 @@
 
   !==================================================================
-  !     
+  !
   !     Purpose
   !     -------
   !     Load atmospheric composition info
-  !     
+  !
   !     Authors
   !     -------
   !     R. Wordsworth (2011)
   !     Allocatable arrays by A. Spiga (2011)
-  !     
+  !
   !==================================================================
 
@@ -54,5 +54,5 @@
 
         ! find variable gas (if any)
-        if(gfrac(igas).eq.-1.0)then 
+        if(gfrac(igas).eq.-1.0)then
            if(vgas.eq.0)then
               vgas=igas
@@ -109,12 +109,14 @@
            igas_C2H2=igas
            count=count+1
-        !! GG MODIF 11 Jan 2019
-       elseif (trim(gnom(igas)).eq."OCS") then
+        elseif (trim(gnom(igas)).eq."C2H4") then
+           igas_C2H4=igas
+           count=count+1
+        elseif (trim(gnom(igas)).eq."OCS") then
            igas_OCS=igas
            count=count+1
-       elseif (trim(gnom(igas)).eq."HCl") then
+        elseif (trim(gnom(igas)).eq."HCl") then
            igas_HCl=igas
            count=count+1
-       elseif (trim(gnom(igas)).eq."HF") then
+        elseif (trim(gnom(igas)).eq."HF") then
            igas_HF=igas
            count=count+1