diff --git a/ece2cmor3/resources/ifspar.json b/ece2cmor3/resources/ifspar.json
index 5cde4326..10c10acc 100644
--- a/ece2cmor3/resources/ifspar.json
+++ b/ece2cmor3/resources/ifspar.json
@@ -179,8 +179,11 @@
         "convert": "frac2percent"
     },
     {
-        "source": "34.128",
-        "target": "tos"
+        "source": "34.129",
+        "target": "tos",
+        "expr": "var34 / (var172<=0.5)",
+        "convert": "K2degC",
+        "masked": "sea"
     },
     {
         "source": "44.128",