Papers in Meteorology and Geophysics
Online ISSN : 1880-6643
Print ISSN : 0031-126X
ISSN-L : 0031-126X
Volume 20, Issue 1
Displaying 1-5 of 5 articles from this issue
  • Masaru Imada, Hiroshi Matano, Iwao Komatsu
    1969 Volume 20 Issue 1 Pages 1-26
    Published: July 25, 1969
    Released on J-STAGE: December 11, 2012
    JOURNAL FREE ACCESS
    The present essay reports on the method of predicting the possible center of a cloudburst which uses the concept of air-layer pregnant with instability, and on its application to some typical cases of cloudburst experienced in recent years in the western part of Japan. The result shows that the method, incorporated in synoptic operation, can be fairly well applied to the prediction of the burst-point.
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  • New Methods of Measurement for the Larger Cloud Drops
    Yoshio Sasyo
    1969 Volume 20 Issue 1 Pages 27-40
    Published: July 25, 1969
    Released on J-STAGE: December 11, 2012
    JOURNAL FREE ACCESS
    New methods of measuring larger cloud drops of diameters exceeding 50 microns are described. The paper consists of two parts. The development of a new instrument, based on the principle of the raindrop sensor, for picking up and counting the larger drops from among all the drops impinging on the sensor is described in Part I. In the second part, the superiority of the photographic emulsion for determining the size spectrum of large drops is described as well as a simple procedure to obtain the permanent records of the size spectrum. Part I New instrument for counting larger cloud drops
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  • New Instrument for Measurement of Wind Direction in Light Air
    Yoshio Sasyo
    1969 Volume 20 Issue 1 Pages 41-48
    Published: July 25, 1969
    Released on J-STAGE: December 11, 2012
    JOURNAL FREE ACCESS
    A new instrument was designed for measuring the wind direction in light air. Four hot wire sensors are placed each at one of the cardinal points based on the principle of the hot wire anemometer. The wind direction is indicated as one of the eight directions. The instrument can be used for wind speeds down to 15 cm/sec. Some preliminary measurements using this instrument were made in connection with cloud physical observation of river fog.
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  • Kiyoo Wadati, Takuzo Hirono, Tetsuo Yumura
    1969 Volume 20 Issue 1 Pages 49-78
    Published: July 25, 1969
    Released on J-STAGE: December 11, 2012
    JOURNAL FREE ACCESS
    S-waves of 51 deep earthquakes observed during the past 30 years around Japan were examined for the purpose of studying their attenuation caused by passing through different geographical locations and depths.
    First, log A/T-Δ curves were prepared and their relation to the respective seismic paths was investigated. Corrections were made to obtain A, taking into consideration the effects from geometrical dispersion in space, azimuthal distribution by the mechanism of earthquake occurrence, and reflection at the surface.
    A close relation between the attenua t ion along a seismic path and seismic active space was found, and various types of observed seismic motions on the ground were interpreted.
    Seismic active space ( SA-zone) is composed of shallow and deep ones (SSA- and D SA-zone) and they meet under the MS (Morioka-Shirakawa) line in East Japan and the BK (Beppu-Kagoshima) line in Kyushu.
    Vertical distance of the gap of these two zones is about 100 km near the line of joint, and that part corresponds to the portion of the largest attenuation. This portion is located under the zone of active volcanoes. The wider the gap, the weaker is attenuation with increasing horizontal distance towards the west of MS and BK lines. The well-known phenomenon about the abnormal distribution of seismic intensities in Japan was explained from the results of this investigation.
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  • Sei Takagi
    1969 Volume 20 Issue 1 Pages 79-89
    Published: July 25, 1969
    Released on J-STAGE: December 11, 2012
    JOURNAL FREE ACCESS
    It has been generally understood the seismic intensity has a good correlation to the maximum acceleration of seismic ground motions. In the present study, it was found that seismic intensity has a better correlation to the maximum energy of seismic waves rather than to maximum acceleration. The material was taken from the seismic data obtained at the Nagano Weather Station for the Matsushiro swarm earthquakes.
    Fig.1 illustrates the relation between the maximum displacement and seismic intensity, which shows a fairly good correlation except for Intensity I. Fig.2 illustrates the relation between the maximum velocity of seismic waves and intensity. In intensities IV and V, the linearity is poor. Fig.3 illustrates the relation between maximum acceleration and intensity. In intensities, I and II, the deviation is large. Accordingly, the logarithm of maximum acceleration and seismic intensity does not have a simple linear relation.
    The relation between the maximum energy of seismic waves and seismic intensity is shown in Fig.4, which gives a good linearity all the way from I to V. Fig.5 shows the relation between the total energy of seismic waves and intensity, in which the deviation is large again in I, II and V.
    All these results, the author believes, well support the statement made above.
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