The energetics of stationary disturbances is theoretically studied by means of the linearized form of the primitive equations of motion. Topographic and diabatic effects are prescribed as forcing. As the basic zonal current depending upon pressure, we have employed the winter normal conditions at 35°N latitude and at 60°N latitude. Our main interest will be to determine how the stationary disturbances are altered under different zonal currents and when changes in the lateral kinematic eddy-viscosity coefficient and surface friction coefficient are made. The characteristics of the topographically excited disturbances of wave numbers about 3 is such that they can vertically transport sizable amounts of energy upward in the form of geopotential, after receiving kinetic energy through mountain effect and importing available potential energy from the zonal mean field. The upward transfer of geopotential is less pronounced at 60°N latitude than at 35°N latitude where the subtropical jet stream is located near 250mb. As for the thermally induced disturbances, a large amount of upward energy transfer occurs only at 60°N latitude where the vertical profile of zonal wind is characterized by the existence of the polar night jet stream, while no possibility of this type of upward transfer exists at 35°N latitude.
A study of the source regions of winter monsoon clouds in relation to orographic features revealed that the cloud-free paths and the off-shore distance of the initial clouds measured along stream-lines are closely related to the height of the mountains and the intensity of the monsoon. The patterns of clouds after their formation are found to vary according to the vertical wind shear, changing from convection cells with weak shear to transverse bands with moderate shear and longitudinal bands with strong shear. Following the study of cloud formations, the uses of satellite and aerological data in estimating evaporation from the sea surface were explored. It was found that the water content of monsoon clouds is con- siderably smaller than what might be expected through adiabatic rising processes. The ratio of actual to adiabatic water content was estimated to be about 0.6 over the Sea of Japan and about 0.7 over the western Pacific under the influence of a strong winter monsoon.
A study is made of cellular cumulus convection in a conditionally unstable atmosphere which is unstable for moist ascending motion and stable for dry descending motion. The convection cell under consideration is confined in a cylindrical column : the inside column corresponds to a moist ascending region and the outside annular column corresponds to a dry descending region, while there are an inflow in the lower layer and an outflow in the upper layer. Attention is focused mainly on the evaluation of steady upward heat transport for various values of the size of the cell and the ratio between the ascending and descending areas. A preferred mode of convection is determined by assuming that convection must develop to maximize upward heat transport. It is shown that the present model reduces to a buoyant plume model as a special case when the horizontal scale of the convection cell becomes small compared to its depth and the descending area becomes large.
Heat transfer from the sea to the air over the Gulf Stream off the East Coast of the United States is treated by use of the data at an occasion of cold air outbreak on December 11th through 13th in 1957. Sverdrup's formula gives extreme values of sensible heat transfer by convection, because the Bowen ratio exceeded 0.5 owing to the extraordinary large air-sea temperature differences. The total heat transfer computed from heat and vapor exchange formulae at the sea surface is compared with the one estimated from the reconstructed atmospheric soundings along two trojectories across the Gulf Stream. The results by the two methods reasonably agree with each other. The change of vertical temperature profiles in a cold air mass moving into the warm water is determined by solving a classical diffusion equation and is compared with the observed profiles.