Numerical experiments are performed to investigate to what extent the observed features are explained in terms of the dynamical modification of air flow by the realistic Mars topography. The real Mars topography based on radar- and optical observations is incorporated in the fully non-linear shallow water equations with realistic Coriolis parameter. These equations are integrated numerically as an initial and boundary value problem for air flow across mountain. Comparison of results with the observed data shows the following; 1) In spite of a limitation that the baroclinic effect is ignored, the quasi-stationary troughs and ridges are realized and they are highly in agreement with observed circulation patterns. This result endorses that the observed permanent low or steady flow on Mars appears under the strong influence of orography. 2) The present numerical experiments also suggest that in the northern hemisphere, north winds intensified by orography would be considerably responsible for the courses of “darkening waves”.
The transport properties of stationary waves superposed on a basic zonal current with horizontal and vertical shears in a rotating stratified fluid are discussed. The wave momentum fluxes are derived directly from equations of motion, by introducing the Lagrangian displacements into the Eulerian formulations. The wave momentum consists of two parts; one is the relative (to the rotating system) zonal momentum of a fluid particle, and the other is the momentum excess or deficit due to the meridional displacement of the particle. It is shown that the meridional mass flux is proportional to the vertical transport of momentum excess or deficit due to the meridional displacement. If the mass flux is directed southwards, the momentum deficit is transported upwards. It is shown that the zonal component of wave momentum flux is solenoidal in the meridional plane and that the physical meaning of the Eliassen-Palm's (1961) stream function is that of zonal mementum flux. It is also shown that the divergence of wave energy flux is given by the inner product of the wave momentum flux and the velocity gradient tensor of the basic zonal current. This implies that the concept of momentum radiation by wave may be still appropriate and useful in the rotating case.
The behaviors of the cloud systems in the tropical Pacific region were analyzed by making use of the spectral method especially paying attention to the lateral propagations of the disturbances. Throughout the analysis, two kinds of disturbances were found : one belongs to the longer period than ten days and another does to the short period with four or five days. The longer period cloud system is estimated to be propagated from the mid-latitude to the equatorial zone at nearly 130-140°W. Such behavior of the long-period disturbance satisfies the theoretical regime of lateral propagation. The shorter period cloud system may be self-induced within the equatorial zone.
Based on six-hourly precipitation and upper-air observations over the Kyushu Islandfor ten years pre-summer rainy seasons (Baiu) from 1962 to 1971, statistical relationships are studied on the amount of precipitation and the tropospheric wind speed. It is clearly shown that the amount of precipitation is highly correlated with the lower tropospheric wind speed and higher correlation coefficient is obtained for later wind speed, which supports the hypothesis that the momentum in the lower troposphere is increased as a result of convective activity. In cases of heavy precipitation, unbalanced low-level jets are most likely to appear and the maximum frequency of wind speed is observed around 18m/sec throughout the troposphere.
It is shown in the Part I of this report that the active echoes in Baiu Front are organized into medium-scale echo clusters. The characteristic structure of echo clusters will be analyzed in this paper by using the data of the dense aerological observation network. The detailed analysis reveals warm core in the upper troposphere above the deep moist layer associated with low level convergence within the echo cluster. Another important feature is the intensification of the low level wind within the echo cluster. The strong convective precipitation within the echo luster suggest that the warm core and the strong wind in the lower layer are caused by the convective warming and the vertical mixing of the momentum due to the convective motions respectively. Basing on the results of the analysis, a synoptic model of the medium-scale echo clusters in Baiu Front will be proposed.
Basing on data of global radiation both in total and spectral wavelengths on clear days from 1961 through 1971 the influence of pollution was discussed on the urban atmosphere of Tokyo. Decrease of radiation intensity by 10-15% during this period was noticed which may be attributed to the progress of air pollution in Tokyo. Correlations between various radiation data were calculated. Results showed a spatially homogeneous status in the central part of Tokyo. Infrared and visible data showed an extremely similar behaviour in contrast with the fact that ultraviolet radiation showed rather complex fluctuations. Correlation between radiation data and wind speed was calculated in varying wind directions. Results showed specific directional tendencies which indicated the influence of industrial areas as pollutant source. Some interpretations were given on the physics of the observed phenomena.
Transition from the surface layer to the free convection layer of the unstable atmospheric boundary layer is discussed mainly from the standpoint of the budget relations of thermal variance and kinetic energy. The data used here cover a wide range of stability for unstable conditions (0.1<-z/L<62) obtained over the Bonneville Salt Flats Utah in 1970. The dimensionless terms in the budget equations obey the Obukhov's similarity law. The thermal variance transport term changes sign from divergence to convergence around -z/L =1as-z/L increases. This is approximately balanced by the difference between the production and the dissipation rate throughout the analyzed stability range. Dissipation rates of kinetic energy and temperature fluctuations are well related to the spectral peak wavelength. The spectral peak wavelength and the length scale determined by the dissipation and the total variances decreases with - z/L for temperature fluctuations, but increases for vertical velocity fluctuations. They approach the same constant value for large - z/L. For strong instability those terms obey the free convection similarity law. The critical height and the stability at which this law becomes valid (the height of the transition) lies in 1<-z/L<5.