aquatic estuarine layer liquid air-water interface layer estuarine open water surface layer envoCmecs https://cmecscatalog.org/cmecs/classification/unit/599.html A layer of estuarine water which extends a few centimeters from the surface of the water column towards the estuary bed and from a fiat boundary where the estuary bed below the water column reaches a depth of 4 meters until the end of the estuary most distal from the coast. CMECS:599 envoMarine This class aligns to the Coastal and Marine Ecological Classification Standard (CMECS). In ENVO, we may adapt the definition for consistency, but the semantics (meaning) of the term should be unaffected. Please consult the CMECS catalogue (https://cmecscatalog.org/) for authoritative and semantically unconstrained definitions. surface of an astronomical body