Solar radiation and time lag e rrors are pointed out as the main source of the serious systematic errors in the temperature measurement at high altitudes. The correction for the radiation errors of Japanese radiosonde has been performed for aerological data above 400 mb, while that for the time lag error has been placed out of consideration. The purpose of the present paper is to clarify whether or not the now employed correction for radiation errors fulfils sufficiently the requirements to obtain a true value of the ambient temperature and further, to estimate the magnitude of time lag errors at each altitude. In order to achieve the above mentioned purpose, an improved radiosonde temperature element had been developed, which consists of two bimetal strips, one silver plated and the other blackened, so as to selfcompensate for the effect of solar radiation. A series of comparative flight tests and numerous experiments had been made to assess the magnitude of radiation and time lag errors of the shielded temperature element with a ventilation duct. These results show that the solar radiation error at any altitude amounts to more than twice the magnitude of the correction now employed for the solar elevation angle 30°, and the time lag coefficient to about 280sec at 20 mb,120sec at 50mb, and 40sec at 200mb, and 14sec at 1000mb. The observed temperature differences between day and night observations carried out in Feb.,1956, were found to be fairly greater than the expected errors. It suggests that the magnitude of the diurnal variation of temperature amounts to 0.3°C at 50 mb, 0.15°C at 100 mb, the probable accuracy of the measuring instrument being permitted to be ±0.5°C. This paper summarizes the experimental results that were obtained in our laboratory during the interval from Apr.,1955 to Feb.,1956. In this paper, the principle and construction of the improved bimetal thermometer is described and also the results of a series of comparative tests on the radiation and time lag errors of Japanese radiosondes are shown.
Seven configurations of two-di rectional wind vane, i.e., a device to measure simultaneously both horizontal and vertical directions of wind, are tested in wind tunnel, their periods of oscillation and time constants are evaluated and reduced on the basis of simple geometrical and kinematical relations. For the spinning vane the gyroscopic and Magnus effects should further be considered. For the vanes with axial asymmetry and for those with axial symmetry beyond certain amplitude, the phase difference between horizontal and vertical oscillations must be tolerated. For all vanes the period and the time constant of oscillation, i.e., the time during which the initial amplitude decreases to 1/e are both of the order of one second per 10 m/s wind speed and diminishes in inverse proportion of the wind speed. For other vanes with different geometrical and kinematical configurations, simple reduction formulae are given.
The writer made a consecutive study of the earthquake swarms which occurred accompanied by the volcanic activity of Volcano Usu, Hokkaido, from December 1943 to October 1945. The famous Showa Shinzan was born in the course of this activity. As a sequel to the first and second papers, the writer prepared this third paper in which the following problems are discussed. 1). As a result of the study of the earthquakes (A-type earthquakes)that occurred prior to eruptions, the writer obtained the value of the distance coefficient, k=8.2 km/sec, near Showa Shinzan. At the same time the depth of the hypocenter was determined to be about 10 km. By using k=8.2 km/sec, the distribution of the epicenters of A-type earthquakes was studied. 2). From the decay formula of the maximum amplitude for surface waves A=A0 Δ-1/2e-aΔ, the value α was obtained as follows: α= 5.8 × 10-3 km-1 (25<4<700 km), α=5.6 × 10-3 km-1 (25<4<800 km). By the following formulas the decay of frequency N and ground amplitude A with the lapse of time were studied. N (t)=K (t + C)-p, A (t)=K' (t + C')-P', where K, K', C, C', p and p' are constants. These constants were obtained from the data of the A-type earthquakes observed at Muroran, Mori and Sapporo. 3). In the waves of all earthquakes of A-type recorded by the seismograph at Mori Observatory (Mori Weather Station), S'-waves, reflected S-waves, were found several seconds after S-waves, and the depth of the Moho discontinuity was calculated as H=25.0 km (mean value). 4). Energy of earthquakes and energy of ground uphea val were calculated, and their relation to the number of earthquakes and to other phenomena were considered. 5). In the seism ograms at Mori Observatory two new phases were discovered. These were tentatively named the third phase and the fourth phase. Most of the path of the seismic waves are in shallow sea water. The waves were treated as Rayleigh waves, and various conditions were given to the crustal structure of “liquid-liquid-solid ”layers or “liquidsolidsolid ”layers. The dispersion curves of Rayleigh waves for every case were computed by IBM 704 electronic computer. The sedimentary layer, or the second layer, was assumed to be solid, and importance was attached to this layer. By assuming a condition such that the velocity of the compressional wave is smaller than that of the first layer, and by adjusting the ratio of the thickness, a result was obtained, by which the above-mentioned 3rd and 4th phases might be most satisfactorily explained. Thus an important hint was obtained, in regard to the na ture and effect of the sedimentary layer. 6). The values of m in the Ishimoto-Iida's formula, n dA=K A-m d A, are calculated by the use of data of the Ito crypto-volcanic activity and the Kita-Izu earthquake swarms in 1930. By means of cumulative frequenc y calculation, mean values for the above two groups were respectively given, as m= 1.85 and m These values were compared with those obtained from the forerunning earthquakes of Usu volcanic eruption.
Selection of deep shocks is made by examining the seismogram form and by measuring the apparent velocity according to the method proposed in Chapter II. The number of deep shocks thus found, in and near Japan, the magnitude of which is less than 5, is 69 in July, October, November, December,1959 and January,1960. By comparing this number with the frequency of larger deep shocks, the following conclusion has been drawn: the rate of increase in frequency of small deep shocks with decreasing magnitude is significantly smaller than that of large deep shocks or shallow shocks. Aftershocks of deep shocks also seem to be lower in frequency than those of shallow shocks. In addition to the above facts, the following has also been concluded: (1) the direct waves from the origin are preserved in the part which is close to the onset, but the wave conversion takes place even just after the onset, and (2) the seismogram form is one of the most valuable seismometrical data. It should be noted that the present investigation has been made possible by the highly “ zweckmdssig ” observation. Chapter IV. Tripartite observation at Matsushiro
It has been usual to consider the effects near the earth even for that part of cosmic rays with solar origin. An examination of the conditions near the source, the sun, shows that the emission has taken place only from limited portions-western limb and C. M. in a small latitudinal belt on either side of the equator-of an extremely active solar region with long history, whose area is relatively large and compact and whose magnetic field is marked. The concurrent ionospheric and subsequent geomagnetic effects have also been considered. The large geophysical events seem definitely controlled by the conditions on the sun.
The relation between radioactive fallout and meteorological conditions was studied. The relation of rainfall amount to fallout (R) can be expressed fairly well by the formula R=C (1-e-βP+κP), where P is the amount of rainfall, C is the air activity,β and κ are constants. There is little correlation between the surface weather conditions and fallout while a considerably higher correlation was found among a trough at 500 mb, position of jet stream and air activity. The activity increases remarkably when a trough at 500 alb passes above, and a core of jet stream is located above or a little south of an observation point. The analytical results of Sr-90 deposition in Japan since 1954 and its seasonal variation were also discussed.
Although numerous measurements have been made on the radioactive contamination near sea level, our knowledge of the contamination of radioactive dusts in the upper atmosphere is still very imperfect. “Radioactivitysonde ”, which is the combination of balloon-borne instruments and telemetering technics, is utilized for the radioactivity measurements. Our measurements have been made 18 times from 1957 to 1959 at the Aerological Observatory, Tateno, about 50 km northeast of Tokyo (36°03'N 140°08'E).
Sr-90 deposition will generally depends on rainfall, season and geographical location. The relations between them are investigated by coaxial method using the data of six stations in Japan during 1958, and it is found that though Sr-90 deposition increases with rainfall the rate of increasing varies widely with season, and also that local variation is not so large. The relation of concentration of Sr-90 in rain with the amount of rainfall is then obtained from measured values and estimated ones from coaxial graph. The results show that the Sr-90 content in rain varies with rainfall, and where the rainfall is small there is a tendency of the concentration to increase with rainfall. It is difficult to explain this but it seems to be necessary to take this into account when we discuss the problems such as seasonal variation of Sr-90 concentration in rain. It is interesting that almost similar results are obtained with the data of the same period in the U. K.
Analysing the air-masses covering Japan, we can find the origin and the movement of radioactive fallout transported. The fallout originated in the Bikini and in the Arctics are transported with the Ogasawara air-mass and the Siberia air-mass respectively, but the one in the Southwest Siberia is transported from the north with the Siberia air-mass or rapidly from the west with the strong westerlies. The fallout discharged in the troposphere spreads over in a considerably large area in the atmosphere after about 3 months travel from its original site.
There is every indication that the radioactive dusts near the ground surface depend on the surface air pressure pattern; the concentration of radioactive dusts in the air is higher in an anticyclonic area than those in a low pressure area, and the radioactive dusts are also affected bythe surface air current, being higher in regions where the air stagnates.