Parameter Tree:
EARTH SCIENCE > OCEANS > OCEAN CIRCULATION > OCEAN MIXED LAYER

Definition:
Also called the surface zone. The ocean mixed layer is the upper layer
of ocean in which temperature and salinity are relatively constant with
depth. Depending on local conditions, the surface layer may reach to 1,000
meters (3,300 feet) or be absent entirely.  


Reference:
Garrison, T. 1993. Oceanography, an Invitation to Marine Science. Wadsworth
Publishing Co. p. 527.