_:b1218206 "PLB:plb"^^ . _:b1218206 . _:b1218206 . _:b1218206 . _:b1218206 "Wikipedia:Ocean_current"^^ . _:b1218206 "A marine current that generally occurs below the permanent thermocline (where it occurs) or below 400 m depth and that is driven by density and temperature gradients."^^ .