The diurnal variation of the wind and temperature fields in the Ekman layer is studied by solving the equation of motion and of heat conduction. Eddy diffusivity is assumed to take the values which are evaluated by the extrapolated use of a modified KEYPS equation to the Ekman layer. With regard to the boundary conditions, the standard lapse-rate is assumed at the upper boundary and a constant temperature is assumed at the lower boundary which is set up in the soil. In this kind of study, hitherto, the constant flux layers near the surface are assumed in order to avoid a large amount of calculation, but in the present work, the original prognaustic equations of the whole layer are directly integrated by use of the matrix method for finite difference equations. Computation is carried out until cyclic solutions of one day period are obtained. The computed results are compared with observations available to us at present.
A time-dependent model for coupled atmospheric and oceanic boundary layers is described. The model is one-dimensional; hence horizontal gradients of the dependent variables are specified rather than computed. Turbulent viscous and diffusive processes are incorporated by means of the eddy coefficient concept. Using a formulation which is in accord with both surface and Ekman layer observations, the vertical dependence of the eddy coefficient is specified a priori. Experiments with the model were performed with input conditions representative of the climatology of the Gulf of St. Lawrence in autumn and winter. Fairly reasonable profiles of wind, current, stress, temperature, humidity and salinity were obtained. The water surface temperature and the surface fluxes were also reasonably behaved functions of time. The exact date of freeze-up, however, was rather sensitive to the amount of oceanic cold advection determined from the specified oceanic temperature gradients and the calculated ocean current.
In order to investigate the characteristics of the lee waves, numerical experiments are performed by integrating the equations of the so-called Boussinesq system as an initial value problem for a given topography with rigid upper boundary. Some considerations on the linear theory are presented for a better understanding of the results. For almost all internal Froude number Fi, a quasi-steady pattern is obtained. Calculated patterns are discussed in connection with the linear theory, and good agreements are obtained. For relatively large values of the Fi, a laminar sinusoidal flow is obtained. On the other hand for small values of the Fi, a S-shaped or Rotor-like flow pattern is obtained, in which a statically unstable region is found to survive. Such a flow may be considered as a result of a nonlinear interference of the waves. Occurrence of such an overturning flow also depends on the height of the mountain. The criterion for the overturning flow seems to be linear dependency in terms of the nondimensional mountain height D and Fi, which appears to be consistent with Long's analytical study (1955). Strong lee-side surface winds are discussed in relation to the simulated lee waves. The possibility of a strong downslope wind or horizontal wind at the lee side of the mountain is stressed.
An experimental study of the dynamic instability in a rotating system is presented. The basic jet is made by rubbing the free surface of water in rigid rotation with a solid plate. The structure of the basic jet is studied by a linear theory on the vertical free shear layers. The beta-effect is simulated by variation of the fluid depth. When the Rossby number exceeds a certain critical value, the zonal jet becomes unstable and a disturbance with a specific wave number appears. By comparing the observed wave numbers with relevant linear theories, the following results are obtained. (i) The observed marginal state better fits the theory in which the jet is stabilized by the beta-effect than the theory in which the jet is stabilized by the internal viscosity. (ii) The observed results show that the westerly jet is more stable than the easterly jet. (iii) The observed wave number rapidly decreases from the linear mode, when the Rossby number increases from the critical value.
The air-mass modification is very remarkable over the East China Sea in wintertime, where the warm sea current Kuroshio is very warm. The variation in the heat energy budget situation over this area is studied during 20-day period in February of 1968. From the analyses of ESSA cloud pictures and data of aerological and radar observations, it is shown that the wave disturbances with a period of about 4 days predominate over the analysed area. The synoptic situation in the lower troposphere as well as the situation of the heat energy budget varies remarkably when the wave cyclone passed over this area. The synoptic situations of this area are classified into two typical situations, i.e. the cold air outbreak occurring after the passage of cyclones and the northward invasion of the subtropical air-mass occurring when the disturbance is located on the AMTEX area. The budget for the former synoptic situation (i.e the cold air outbreak) is characterized by the large amount of heat energy supply from the sea and the large positive value of individual change of temperature and mixing ratio in the lower troposphere under the stable layer. The influence of air-mass modification is confined within the lower layer since the penetrative convections, which redistribute the heat energy in the free atmosphere, are suppressed by the stable layer which developed in the subsiding polar air mass. The budget for the latter synoptic situation is characterized by the strong convergence of water vapor flux in the lower troposphere, very large positive and negative values of the individual change of temperature and mixing ratio in the middle troposphere. More than 30% of the heat energy, which supplied from the sea surface, is transported upward across the 700-mb surface through the work of cumulus convection developing in the thick layer of moist neutral stratification.
An Objective Analysis Model is presented which will handle the four-dimensional data assimilation problem where observations are randomly situated in both space and time. The structure functions of both the desired atmospheric signal and the system plus geophysical noise are modelled and used to produce the required weight functions. Modelling of the dynamics of the atmosphere is incorporated through the use of linear constraints in the hypothesis testing. The resulting analysis is a maximum likelihood, least squares (in the population sense) production and has associated fields of confidence limits.
Characteristic features, such as the mass, bulk density, riming states and the ratio of the length along c-axis to that along a-axis of snow crystals developed along c-axis (column, sheath and needle) are discussed on the basis of observations at Shiga Heights (about 1600 m above sea level), in central Japan. The masses of needles were found to be small compared with those of columns of the same volume, that is the values of the bulk density of needles were smaller than those of columns. The values of the bulk density of needles ranged between 0.2 to 0.4 grcm-3, irrespective of the length along c-axis. On the other hand, the values of the bulk density of columns were widely scattered. The crystals whose masses exceed 1-3×10-3mg were mostly rimed. Riming properties of columnar crystals are in good agreement with the observations by Ono (1969).
Mortality of early infancy and children in Japan (converted into annual deaths against 1, 000 live births) is calculated month by month for 1961-67, with monthly deaths duely adjusted separately for early infants 0-1 year old and children 1-5 years old. Regarded as a time series, it is analyzed by the Census Method II X-11 (developed by the U.S. Census Bureau) for five age groups, i.e. early infants 0-1 year, and children 1-2 years, 2-3 years, 3-4 years and 4-5 years old. (Deaths of these age groups are collectively named infant mortality in this paper simply for sake of linguistic convenience.) It is thus found to show a seasonal variation peculiar to each age group. For early infants under 1 year, for instance, (1) mortality is considerably high in winter, (2) its seasonal variation is getting smaller as a whole, and (3) it begins to curve up in summer as well as in winter, though slightly. For other age groups, however, the seasonal pattern of mortality varies differently: (1) mortality is rather high from winter through summer for 1-2 years old, and (2) it is relatively low in winter for 2-5 years old. Then, with accidental deaths (mostly drowning) or the most frequent death cause for children omitted, infant mortality is recalculated and the time series thus adjusted is analyzed by the X-11 method for the five age groups. It is found that the seasonal variation shows little difference before and after adjustment (removal of accidental deaths) for early infants under 1 year, and that the "adjusted" variation for 1-2 years old curves up conspicuously in winter and slightly in summer, indicating the similarity in pattern and range between the first two age groups. For 2-5 years old, be it noted, the range of variation becomes tangibly smaller with short-cycle ups and downs, though somewhat peculiar changes are seen in pattern. It might well be concluded that infants under 2 years old are liable to suffer from seasonalchanges in both winter and summer, and that children 2-5 years old are well able to endure seasonal influences, winter cold and summer heat in particular.
During the passage of the Second Miyakojima Typhoon the barograph at Miyakojima recorded a pronounced pressure oscillation with the period of about 50 min on September 5, 1966. The recorded oscillation extended over half a day and had a maximum double amplitude exceeding 10mb. Simultaneously, wind and rainfall intensity showed periodic variations with the approximately same period, too. It is shown that the periodic variations of these elements were associated with the counter-clockwise rotation of an elliptical eye revealed by radar observation.