Water circulation in the Japan Sea is characterized as a formation of the Japan Sea Proper Water from the data observed in 1969 by research vessels belonging to the Japan Meteorological Agency. Below 500m depth in the Japan Sea, salinity is relatively high in the northern part and low in the southern. This is opposite to the conditions in the surface layer, where the northern part is generally the Cold Current Region and the southern part the Warm Current Region. In the southern part of the eastern Japan Basin of the northern Japan Sea, anticyclonic circulation occurs and sea waters sink towards the bottom. In the western Japan Basin and in the Yamato Basin, sea waters flow upward, in contrast to the southern part of the eastern Japan Basin. Therefore vertical water circulation generates in the deep layer of the Japan Sea, that is, downwelling appears in the southern part of the eastern Japan Basin, and upwelling occurs in the western Japan Basin and in the Yamato Basin.
Verkley (1987, 1990) constructed modons on a sphere as models of atmospheric blocking phenomena. These are exact solitary wave solutions to the barotropic potential vorticity equation on a sphere. In this paper, the linear Liapunov stability of Verkley's 1987 modons is proved by means of Arnol'd's invariant, and moreover it is shown that Verkley's 1990 modons are linearly spectrally stable. In spite of the fact that Arnol'd's invariant does not exist for the 1990 modon, it is still possible for the 1990 modon to be proved linearly spectrally stable because of the fact that the 1990 modon is a limiting case of the 1987 modon.
The turbulent Ekman boundary layer in a neutral atmosphere is studied by means of a second order turbulence closure model incorporated with a prognostic equation for the master length scale and those of a one-and-a-half order closure model. The results of the second order closure model are compared with those of a second order closure model incorporated with an equation for the dissipation rate, an E-ε model and a direct numerical simulation. It is shown that the height of the Ekman layer simulated by the present model is higher than those by the other closure models and that the turbulence kinetic energy and turbulent momentum fluxes in the upper part of the boundary layer are larger. These differences result from the fact that the length scale predicted by the present model is longer than those by the other closure models. The structure of the Ekman boundary layer simulated by the present second order closure model is close to that by a direct numerical simulation. The results of the one-and-a-half order closure model coincide with the present results, though it is found that the growth of the boundary layer is a little slower than that of the present second order closure model.