Papers in Meteorology and Geophysics
Online ISSN : 1880-6643
Print ISSN : 0031-126X
ISSN-L : 0031-126X
Volume 31 , Issue 3+4
Showing 1-7 articles out of 7 articles from the selected issue
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  • Tatsushi Tokioka
    1980 Volume 31 Issue 3+4 Pages 115-123
    Published: 1980
    Released: March 09, 2007
       A parameterization of subgridscale mixing based on quasi-geostrophic turbulence theory is presented. In this parameterization, not only the horizontal diffusion coefficients for momentum and heat, but also the vertical diffusion coefficients for momentum and heat are uniquely determined. A form of the mixing is derived which simulates the subgridscale mixing process in the inertial subrange of enstrophy cascade.
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  • Tatsuo Hanafusa, Tokunosuke Fujitani, Noboru Banno
    1980 Volume 31 Issue 3+4 Pages 125-152
    Published: 1980
    Released: March 09, 2007
       A meteorological observation tower at Tsukuba Science City is equipped with mean wind, temperature and humidity sensors, together with instruments for the measurement of their short period fluctuations at seven levels (including the top of the tower) ranging from 10 m to 213 m above the base of the tower.
       The general statistical properties of wind data for one year are discussed in this paper together with the tower facilities including the data acquisition system.
       The annual arithmetic mean wind speeds increase from 3.14 m/s at the 25 m level to 6.09 m/s at the top level. The annual mean wind speed at the 25 m level is highest during the daytime and one at the 213 m level at night. Monthly relative frequency distribution of wind speed can be well simulated with Weibull distribution.
       Annual relative frequency of wind direction has three clear peaks, which are very similar to the climatological data obtained at the Tateno Aerological Observatory near the Meteorological Research Institute.
       The characteristics of vector wind speed are examined and the monthly mean profiles from May to September seem to be explained by the geostrophic wind.
       The power spectra of wind speed in summer and fall have a remarkable peak of daily cycle and a relatively large peak with 3-4 days period in winter and spring.
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  • An Improved Method to Remove Hygroscopic Materials Collected on a Membrane Filter
    Toyoaki Tanaka
    1980 Volume 31 Issue 3+4 Pages 153-171
    Published: 1980
    Released: March 09, 2007
       Hygroscopic materials in the air are collected on a membrane filter together with ice nuclei. They behave as a strong vapour sink and interfere with the detection of ice nuclei in the diffusion chamber. To remove hygroscopic materials from the specimen filter, a simple method was developed that was a kind of dialysis to float the filter on the surface of distilled water. The method was applied to the volcanic ash samples collected on the filter. Dialyzed and controlled specimen filters were subjected to the morphological test of particles by means of the electron microscope and to the test of ice nucleation by the use of the diffusion chamber. Supersaturation relative to water being achieved in the diffusion chamber was confirmed by Bergeron-Findeisen effect that appeared in the processing of specimen filters.
       No difference was observed in the morphology of particles between controlled and dialyzed specimens. However, water soluble components were detected in the water used for dialysis. Thus volcanic ash particles were deduced to be mixed nuclei which consist of solid particles and water soluble components.
       The ice nucleating activity of volcanic ash increased with decreasing temperature and with increasing supersaturation relative to ice. The dialyzed volcanic ash showed 2 or 3 times higher activity of ice nucleation than the controlled within the temperature range from -12 to -25°C and the humidity range of 13 to 35% supersaturation relative to ice.
       On the basis of the nature of volcanic ash as mixed nuclei and the temperature and humidity dependence of ice nucleating activity, the mode of action of volcanic ash was presumed to be primarily a condensation freezing mechanism in the atmosphere.
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  • Tsutomu Takashima, Yozo Takayama
    1980 Volume 31 Issue 3+4 Pages 173-176
    Published: 1980
    Released: March 09, 2007
       The ocean surface was simulated by many facets whose slope is represented by the Gaussian distribution, where the slope of the facets depends upon the isotropic ocean surface wind (Cox and Munk, 1956). Thus the ocean surface wind could be derived from the pattern of the reflected radiation in the sun glint region. The data of the channel 3 (3.55-3.93 μm) of the AVHRR radiometer (NOAA-6) were used and compared with the theoretical computations. The derived results are in good agreement with those of the ground based measurements.
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  • Fujio Kimura
    1980 Volume 31 Issue 3+4 Pages 177-184
    Published: 1980
    Released: March 09, 2007
       Short distance diffusion with chemical reaction experiment was investigated. NO, NO2 and O3 concentrations were measured within 120 m downwind from the source which emitted NO gas continuously into the atmosphere with background ozone. Very large fluctuation of NOx concentration was observed, and average concentrations of instantaneous plumes were obtained. The results show that the sums [NO]+[NO2] and [NO2]+[O3] are conserved under chemical reaction and that the photochemical decomposition rate of NO2 is much smaller than its formation rate during the daytime when travelling time is less than 20 sec. And it is also shown the formation rate of NO2 depends not only upon travelling time but on background ozone concentration, and also on the dilution rate due to turbulent diffusion.
       A simple model of diffusion with reaction which is applicable within short distances from the source is presented. It gives fairly good agreement with observed concentrations in instantaneous plumes.
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  • Yoshimi Suzuki, Yasuo Miyake, Katsuko Saruhashi, Yukio Sugimura
    1980 Volume 31 Issue 3+4 Pages 185-189
    Published: 1980
    Released: March 09, 2007
       Selenium in sea water is present in four different forms, i.e., dissolved inorganic (IV and VI), dissolved organic and particulate organic form. The total content of selenium in dissolved forms is controlled by following factors:
    1. Exchange of water between the shallow and deep layers of the ocean.
    2. Biological production in which dissolved inorganic selenium is transferred into particulate organic form.
    3. Regeneration of dissolved selenium (inorganic and organic) from the particulate organic form of selenium.
    The content of either inorganic or organic selenium in dissolved form is controlled also by oxidative decomposition of dissolved organic selenium.
       It is considered that the ocean can be divided into two layers, i.e., the first layer (0-1,000 m) and the second layer (1,000-5,000 m).
       Mean concentration of Se(IV), Se(VI) and organic selenium dissolved in the first and the second layer in the western North Pacific are as follows:
        (μg 1-1)
    The 1st0.0420.0280.0140.083
    The 2nd0.0580.0630.0080.13


       By assuming appropriate values of rates of different processes controlling the total content of dissolved selenium, the calculation was done concerning the cycle among the different forms of selenium in the ocean. The results of calculation showed that the observed values of the total content of dissolved selenium in two different layers can be explained on the assumption that a steady state is kept in the vertical direction with respect to selenium contents in various forms.
       In the next place, dynamical equilibrium among the different chemical forms of selenium, i.e., selenium IV, selenium VI and organic selenium in both dissolved and particulate forms was studied in the same way as the above. The results showed a fairly good agreement between observation and calculation concerning contents of selenium in various chemical forms in sea water in the two different layers of the ocean.
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  • Mamoru Katsumata, Kiichi Tokunaga
    1980 Volume 31 Issue 3+4 Pages 191-204
    Published: 1980
    Released: March 09, 2007
       Minamidaito, a small island on the Daito Ridge, northern part of the Philippine Basin, is a very favorable position for the receiving of T-waves. The steep slope topography of the sea bottom around the island is also favorable to the conversion from T-waves to seismic waves. The seismograph of Minamidaito-jima (MVI) often records a predominant group of short-period waves, which was converted from T-wave at the near coast of the island. These T-waves are generated by earthquakes in the area along the western margin of the Philippine Sea and in the East China Sea. T-waves from other areas are seldom found.
       The T-waves following shallow earthquakes in the area of the Ryukyu, Taiwan and Philippines might come from the sea bottom near the epicenters, since the apparent velocities from the epicenters to MVI were estimated to be approximately 1.5 km/sec. The velocity of the T-wave itself could be obtained by use of the differences in the arrival times between MVI and the Ocean-Bottom Seismographs of Tokai-oki (off the south coast of central Honshu). It was determined to be 1.483 km/sec with errors of less than 0.2%, which agrees well with the minimum velocity of the SOFAR channel in the Philippine Sea. This supports the theory that the main energy of the T-wave propagates efficiently over large distances as a channel wave in the low velocity layer of the seawater.
       Due to a series of favorable conditions for the generation, propagation and conversion, T-waves following major earthquakes near Luzon Island arrive at Minamidaito Island with large energy, and the seismic tremors by their conversion reach large enough to be perceptible at the coast of the island on rare occasions.
       Although the T-waves generated in the East China Sea are not expected to propagate through the Ryukyu Islands, clear T-waves are also found on the seismic records of MVI from earthquakes of the East China Sea, which include intermediate-depth events. Therefore, it is presumed that these T-waves must be generated away from epicenters by the seismic waves arriving on the sea bottom to the east of the Ryukyu Islands.
       A pair of positions are obtained after an analysis of travel time for an earthquake; one is the position where T-wave was generated by P-wave and the other is that by S-wave. In many cases, the latter seems to be more reasonable than the former as the origin of T-wave.
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