diff --git a/_data/prefixes.yaml b/_data/prefixes.yaml
index 01a600d..9fd2c40 100644
--- a/_data/prefixes.yaml
+++ b/_data/prefixes.yaml
@@ -9,3 +9,5 @@ qudt: http://qudt.org/schema/qudt#
 ignf: http://data.ign.fr/def/ignf#
 inspiregloss: http://inspire.ec.europa.eu/glossary/
 rel: http://www.iana.org/assignments/relation/
+metocean: https://api.meteogate.eu/profiles/metocean/covjson
+sosa: http://www.w3.org/ns/sosa#
diff --git a/context.jsonld b/context.jsonld
index a0028d4..c5361fc 100644
--- a/context.jsonld
+++ b/context.jsonld
@@ -51,7 +51,7 @@
     
     "Parameter": "covjson:Parameter",
     "parameters": { "@id": "covjson:parameter", "@type": "@id", "@container": "@index" },
-    "observedProperty": "ssn:observedProperty",
+    "observedProperty": "sosa:observedProperty",
     "categoryEncoding": "covjson:categoryEncoding",
     "ParameterGroup": "covjson:ParameterGroup",
     "members": { "@id": "covjson:member", "@type": "@vocab", "@container": "@set" },