diff --git a/conf/event-generator/expdef.yml b/conf/event-generator/expdef.yml
index 9383f55ef1c5e89d12fa37e4c1fafa70daf529ac..ad6cda9a629e930080f11d4f226fb0e0535c157a 100644
--- a/conf/event-generator/expdef.yml
+++ b/conf/event-generator/expdef.yml
@@ -3,7 +3,7 @@ experiment:
 #  MEMBERS: "m[1-2]"
   MEMBERS: "m1"
   CHUNKSIZEUNIT: day
-  CHUNKSIZE: 14
-  NUMCHUNKS: 1
+  CHUNKSIZE: 7
+  NUMCHUNKS: 2
   CHUNKINI: 0
   CALENDAR: standard
\ No newline at end of file
diff --git a/namelists/event-generator/icon_atmosphere.namelist b/namelists/event-generator/icon_atmosphere.namelist
index b8243ce0a3aeaaaea7f000de5c058c3bb75a4df8..92a49a234caa38337f55d2a7432d5a5839e35ff8 100644
--- a/namelists/event-generator/icon_atmosphere.namelist
+++ b/namelists/event-generator/icon_atmosphere.namelist
@@ -104,6 +104,10 @@
     flat_height                 = 16000.
 /
 
+&io_nml
+    lnetcdf_flt64_output        = .true.
+/
+
 
 &nonhydrostatic_nml
     iadv_rhotheta=2,