diff --git a/src/cmip_branded_variable_mapper/vertical_label.py b/src/cmip_branded_variable_mapper/vertical_label.py
index 581784d..ee4eea2 100644
--- a/src/cmip_branded_variable_mapper/vertical_label.py
+++ b/src/cmip_branded_variable_mapper/vertical_label.py
@@ -30,6 +30,7 @@
         "olayer700m": "d700m",
         "olayer2000m": "d2000m",
         "op20bar": "op20bar",
+        "osurf": "ols",
         "p10": "10hPa",
         "p100": "100hPa",
         "p200": "200hPa",