The finite-difference scheme of the primitive equations was derived and tested in the so-called x, y, σ-coordinate system which contains the ground as a coordinate surface. The system is suitable for taking into consideration the effect of orography upon the atmospheric motion. The numerical test was attempted for the flow against the bellshaped mountain in a homogeneous and incompressible atmosphere. The results showed the reasonable patterns of pressure and wind, that is, the configuration of trough, ridge, jet core, divergence and vorticity as expected. According to the numerical solution we obtained, our finite-difference scheme seems to be computationally stable and there appears no trouble through 48-hour forecast. Besides, the conservation of the total energy in the forecasting domain was satisfied so accurately that it varied within the range less than 0.03% of the initial value at 48-hour forecast.
Late in June,1961, a severe rainfall occurred in various places in Japan. The numerous data for the various meteorological elements for 12 levels of the troposphere during the heavy rain are adjusted and calculated by the electronic computer. The vertical structure of the heavy rain is analysed in detail. The large-scale pressure pattern of this heavy rain in the neighbourhood of Japan is similar to the typical pattern of heavy rain in early summer in the past. In case of heavy rain, the large-scale pressure pattern is such that the North Pacific high pressure is intense and the movement is stagnant or retrograde to westward in the lower layer of the troposphere. In the upper levels, the ridge over the North Pacific Ocean is similar to the pattern of the lower layer, and further, a typhoon appears over the sea to the south of the Japan Islands or a small-scale distrubance is formed over the Japan Islands. Such a pattern produces the most favorable conditions for the penetration of the strong southerly current into some area of the Japan Islands. In such a case, it is proposed for the vertical structure of the heavy rain that the north-south temperature gradient across the stationary Bai-u front and the subtropical or polar front is very large, and in the lower layer, a severe convergence exists along the stationary Bai-u front and also in the middle layer of the troposphere. In the middle layer, the severe convergence is produ c ed by the confluence of the general current of the westerlies or southwesterlies and the strong southerly current. The variation of the area of the severe convergence for the middle layer and the variation of the area of the heavy rainfall correspond remarkably to each other. The equation of conservation for potential temperature is lastly discussed.
The influence of anomalous solar activity as indicated by the index of solar flares or that of geomagnetic disturbances on the mean variation of atmospheric ozone was investigated statistically by the superposed epoch method on the basis of data covering the period of IGY, IGC and 1960. No appreciable characteristics that exceeded the level of 5% confidence limit were detected in the low latitudinal zone as regards the influence of solar flares. But regarding the effect of anomalous geomagnetic disturbances, the ozone was found to decrease as much as about 1% and 0.5% of the total amount, respectively, on one or two days before the key day in the low latitudinal zone, and on just the key day in the auroral zone. The photochemical processes coming from X-ray enhancement due to solar flare in the former case and of auroral origin in the latter case, were proposed to explain the mechanism of this ozone decrease. Also thermal effect was inferred to follow this which may possibly play an important role in the following dynamical process. Regarding the ozone variation after the geomagnetic key day in the auroral zone, ozone was found to decrease in a remarkable degree on the fifth day and then on the eighth day the longitudinal distribution of the northern hemisphere showed a characteristic wavelike pattern presenting a maximum region in the North Atlantic Area which might be compared with the trough developement in the 300 mb level on the same day in a similar area previously discussed by MACDONALaDn d ROBERTS(1960) or with the tropopause depression pointed out by RASOOL(1961).
A simple basic theory of cup-anemometers is established which shows that a remarkable speeding up of cup rotation is possible by covering one half (the progressive side) of the cup-wheel disc. The amount of the speeding up is estimated to be of the order of 100%. A standard three-cup and a former standard four-cup anemometer of the Japan Meteorological Agency are tested with cover in wind tunnel concerning the rotational speed increase. The effects of covered angle range and off-set angle are also tested. Further the possibility of utilizing the cover with fins attached as a wind vane is discussed.
Integrated amounts of depo sition of Sr-90 and Cs-137 through the end of July 1963 are respectively 45.2 mc/km2 and 125.4 mc/km2 taking the radioactive decay into consideration. From the observation of Sr-90deposition during the one year period since September 1961, it was concluded that the ratio of fission and fusion energy of the explosion which took place in the fall of 1961 would be 1: 5 and the total release of Sr-90 would be about 2 MC. The residence time o f nuclear debris in the stratosphere was newly calculated and the residence time of one year was given as its minimum value. Comparisons were made between the calculated values of Sr-90 from total beta counting data and the observed values by radiochemical analysis. The results showed good agreement during the period from November 1961 to May 1962. The analysis was done with respect to the relation between meteorological conditions and fallout rate and the increase of fallout was observed when the trough at 500mb existed above the observation site. The analytical data of radio-nuclides in rain water collected on 26-27 October 1961 and radio-iodine data in the air of Tokyo from September to December 1961 are listed.