Papers in Meteorology and Geophysics
Online ISSN : 1880-6643
Print ISSN : 0031-126X
ISSN-L : 0031-126X
Volume 48, Issue 2
Displaying 1-3 of 3 articles from this issue
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  • Toshikazu Odaka, Toshimitsu Tsukakoshi, Hiroyuki Takayama
    1997 Volume 48 Issue 2 Pages 41-48
    Published: 1997
    Released on J-STAGE: October 20, 2006
       As regards strike-slip faultings generated inland in Japan, we occasionally observe conjugate fault activity in association with main faultings. In most cases, conjugate faults appear on the side of main faults where frictional force on conjugate faults decreases in response to the main faulting. We present two examples which typically show mutually conjugate activities. These are the pair of the 1978 Izu-Oshima-kinkai earthquake (M7.0) and the 1990 earthquake near Izu-Oshima Island (M6.5) and the pair of the 1984 Western Nagano prefecture earthquake (M6.8) and its largest aftershock (M6.2). It seems rare that conjugate fractures were propagated in regions where frictional forces on conjugate faults were expected to increase.
       These facts indicate that changes in frictional force plays an important role in the generation of secondary fault activity at least in inland strike-slip faults in Japan. In other words, the frictional coefficient in the Coulomb failure function may not be as small as 0.1∼0.3 but as large as 0.5∼0.7 in its value in inland strike-slip faultings in Japan.
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  • Yoshinori Yamada
    1997 Volume 48 Issue 2 Pages 49-65
    Published: 1997
    Released on J-STAGE: October 20, 2006
       Error variance in a horizontal divergence field due to random error in raw radial velocity data was numerically estimated in order to apply the “floating boundary condition” concept developed by Chong and Testud (1983) to the adjustment of vertical wind fields derived from conical-scan-based dual-Doppler radar observation. A filter for interpolating raw radial velocity data onto common grids consisted of a combination of distance-weighted spatial averaging and a Cressman weighting function. Two cases, —shallow and deep—, were considered with error variance and gain estimated for both, using three influence volumes of sphere and oblate spheroids. Results without vertical shear showed for the two cases that the filter retrieved original wind fields well regardless of the shapes of influence volume considered, and that the distortion of wind fields through filtering was negligible for the horizontal scale of meteorological interests to be observed by dual-Doppler radar synthesis. For such a scale, the error variance was considered constant, and was almost equal to that in noise only, in which random noise alone accounted for simulated Doppler velocities. Based on results for noise only, a simple way to estimate error variance in horizontal divergence in terms of rms of random error in raw radial velocity data was presented for different baseline lengths. These estimates may be used for most vertical wind adjustment by floating boundary condition because the presence of vertical shear would not considerably alter estimates.
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  • Hirotada Kanehisa
    1997 Volume 48 Issue 2 Pages 67-71
    Published: 1997
    Released on J-STAGE: October 20, 2006
        A weakly nonlinear correction for the 2-dimensional linear formula of mountain drag is considered. The mountain profile is assumed to be symmetric, and the nondimensional mountain height is assumed to be small and of 0 (ε). To the leading order, the mountain drag is proportional to ε2, and is given by the linear formula. The next order term is proportional to ε4. For a particular mountain profile, the 0 (ε4) correction term is calculated. This correction term is shown to be positive. As a result, at least to 0 (ε4), the nonlinearity can be said to enhance the mountain drag.
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