Papers in Meteorology and Geophysics
Online ISSN : 1880-6643
Print ISSN : 0031-126X
ISSN-L : 0031-126X
Volume 19, Issue 1
Displaying 1-5 of 5 articles from this issue
  • Tadashi Asakura
    1968 Volume 19 Issue 1 Pages 1-68
    Published: July 25, 1968
    Released on J-STAGE: December 11, 2012
    The present paper studies;
    (i) the relationship between the weather in Japan and the upper-air circulations in East Asia which are classified into six flo w types (Part I)
    (ii) the syn optic processes and causes of the formation of blocking flow pattern in East Asia (part II)
    (iii) the causes of Baiu in East Asia relating to the atmospheric circulation and the heat source near the Tibetan Plateau (part III)
    The upper-air flow patterns in East Asia are classified into s ix kinds. They are high index zonal flow, trough flow, summer flow types (which bring about high temperature in Japan) and low index zonal flow, wave flow, blocking flow types (which bring about low temperature in Japan). In general, high index zonal flow, trough flow and blocking flow types bring about much rain, wave flow and low index zonal flow types little rain in Japan. And abnormal weathers in Japan are generally accompanied with the blocking flow pattern in East Asia.
    Next, the synoptic processes that for m a blocking flow pattern in the Shfirin and winter seasons are analysed. The former is responsible for the rainy season in Japan in early autum and the latter for the cold NWmonsoon. A blocking flow pattern in the Shtirin season is initiated by the deformation of westerly flow which is given by a typhoon invasion into a westerly flow. This deformation is transferred downstream with a group velocity, resulting in the splitting of the westerly flow into two branches when the Shtirin season starts. Another blocking flow type in winter is caused by a large-scale heat exchange which is initiated by the development of a ridge over the Atlantic Ocean. With the development of this ridge, the polar air breaks out to Europe and America, resulting in the reinforcement of the ridges over the Asiatic Continent and the west coast of North America. These two ridges progress toward each other and finally fuse into one strong ridge, forming a blocking flow pattern in East Asia.
    In early summer, Japan is visited by the Baiu season with a blocking flow pattern. The beginning of this season and the SW monsoon in India have a close parallelism, and the stronger the monsoon low the stronger the Okhotsk sea high. Furthermore, the stronger the anticyclone over the Tibetan Plateau in early summer, the more predominant the blocking flow in East Asia. These statistical relationships are reexamined by anumerical experiment incorporating the effect of the atmospheric hea t source and sink in early summer.
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  • Shoichi Arakawa
    1968 Volume 19 Issue 1 Pages 69-99
    Published: July 25, 1968
    Released on J-STAGE: December 11, 2012
    Using observed results, the some characters of the fall winds and the Dashikaze (i. e. winds that blow out of the narrow valley) are described, and the existence of an inversion layer above is emphasized. On the basis of these facts an averaged system of equations of air flow under the inversion is derived and then the natures of steady flow in the channel with variable width and height of the bottom are studied. As a result the flows over the mountain and through the narrow valley are found to be affected in the same way, and if the difference in the inversion height exists between windward and lee of these obstacles, then the violent wind may arise in the lee side (or exit part). It is shown that the above theoretical results agree qualitatively very well with some observed
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  • Haruhisa Maruyama
    1968 Volume 19 Issue 1 Pages 101-108
    Published: July 25, 1968
    Released on J-STAGE: December 11, 2012
    Graupel showers formed und e r the winter monsoon situation were frequently observed on the coast of Japanese Archipelago along the Sea of Japan. Graupels ranged from 0.2 to 10 mm in diameter, and their shapes were found to be granular in most cases for small graupels less than 2 mm in diameter. Smaller conical graupels were mostly of circular conical form, whereas larger ones have spherical bases. Thus, it was relatively easy for us to make an estimation of their volumes and accordingly their density. Their density was found to range from 0.3 to 0.5g/cm3, with an average of 0.396 g/cm3, irrespective of size in the region, rangeing from 2 to 7 mm in diameter.
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  • - Frequency Decrease of Aftershock Activity in Its Initial and Later Stages -
    Norio Yamakawa
    1968 Volume 19 Issue 1 Pages 109-119
    Published: July 25, 1968
    Released on J-STAGE: December 11, 2012
    First, it is pointed out th a t the modified Omori formula n(t)=A/(t+c)p proposed by HIRANO and UTSU is more suitable than the formulas n(t)=A/(t+c) and n(t)=A/tp in order to express the frequency decrease of aftershocks for the whole aftershock duration, and that the parameter c of this modified Omori formula has an important geophysical or seismological significance, that is, a measure of time of duration of fracturing phenomena and hence a measure of degree of complexity or dimension of fracture in a focal region of a main shock.
    Then it is also pointed out that the difference of space distribution between aftershock activity in the first stage and that in the later stage, as in the case of aftershock activity of the Niigata earthquake reported in the previous paper, is closely related with the difference of time distribution of the activities between the two stages.
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  • Muneyasu Kano
    1968 Volume 19 Issue 1 Pages 121-129
    Published: July 25, 1968
    Released on J-STAGE: December 11, 2012
    The method for determination of the backscattering function and extinction coefficient of the atmosphere by using a laser radar is presented. It is shown that the backscattering function can be obtained by obserations of laser echoes in two directions with the assumption of a horizontally stratified atmosphere and also that the extinction coefficient can be determined uniquely from the backscattering function in solving a differential equation derived from the laser equation. The accuracy of determination of the extinction coefficient is also discussed.
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