@Maurik
The sounding you provide, shows data from a weather model.
"Surface", on a model, may have different altitude than the real one,
because of the smoothing and depends on model's grid.
Samoens has (real) elevation 700m ...
313ac79b-b3c0-487d-bdca-fbe16c173f46-εικόνα.png
... but ECMWF (grid 9 km) treats it as in 1490 m !!!
d5dfaef9-1c06-446b-a5e6-f8091a8f3a03-εικόνα.png
... ICON-D2 (grid 2.2 km) "shows" surface at 835m (much closer to reality).
d0c8f3db-48e2-4645-b23e-d67a9673f8f4-εικόνα.png