Abstract
Physical behavior of plumes in the ocean was demonstrated by model calculation with some applications to a hydrothermal plume observed in the Okinawa Trough. In a special case where the initial momentum of a plume is so large that the plume was driven mainly by the momentum, a water mass of a colder and lower salinity campared to the surrounding water was formed. In other cases, a wamer and saltier water mass was formed. Concerning the behavior of the plume cloud, some phenomena caused by the differenece between diffusivities of heat and salt were also discussed qualitatively.
