Our newly developed three-dimensional type of sonic anemometer-thermometer has two main benefits compared with the traditional type. One is the “single pair” probe head and the second, “the adoption of the digital calculation of pulse time difference”. The principle of operation of the new type, a comparison with the traditional type and some results obtained in wind tunnel experiment as well as in the field are described in this paper.
We report on the secular and annual changes of tritium (3HOH) concentration in precipitation in Tokyo and Tsukuba. The optium residence time in the stratosphere is estimated to be about 1.7 years by using a reservoir model. The average profile of the annual change shows a similar pattern to that of 90Sr, and their concentration of the second half of the year decreases to about one third of that of the first half, when no nuclear weapon test or small scale releases of fission products took place in the preceding year. The difference of fall rate between tritium and 90Sr along the Japan Sea side of Honshu Island of Japan in the winter season is explained by the difference of vertical distribution in the lower troposphere between them, where the mixing ratio of tritium does not change so much with altitude but the concentration of the fission products increases with altitude.
The sea off the south coast of the Chubu, Japan often receives T-waves with large energy, following major earthquakes near the coast of Luzon, the Philippines. Our previous study has shown that those T-waves were generated near the epicenters and propagated efficiently over long distances through SOFAR channel in sea water. Seismic waves converted from sound waves in sea water to elastic waves in the crust have rarely been observed by sensitive seismographs at inland stations, as at Matsushiro situated more than 200 km away from the south coast of the Chubu. Such seismic records of T-waves start out very gradually and continue for a few minutes, and the wave trains are characterized by short-period vibrations (1/2sec, and less) from start to finish. The locations of the acoustic-to-seismic conversion are estimated to be at a depth of about 500 m on the continental slope off the south coast of the Chubu.
Sea clutters observed on the images of two weather radars of the Naze Weather Station and the R. V. Keifu-maru are analysed to use them in determining the sea surface winds. Their usefulness is established but some problems to be solved are pointed out. The observed intensity of the sea clutter is proportional to uγ, where u is the wind speed and γ the constant which was about twice the value observed on aircraft. The observed directional distribution of sea clutters differs from the distribution in the case of incidence angles of 20°∼80° in that the former shows the strongest intensity in the upwind direction and the weakest in the downwind direction while the latter has one maximum intensity each in the upwind and the downwind direction and one minimum each in the two crosswind directions. It is known that the sea clutter of EM waves is mostly due to the Bragg scattering in the range of incidence angle between 20° and 80° which is adopted in the air-borne and satellite-borne scatterometers. In the case of an incidence angle of about 90° the sea backscatter is also due to the Bragg scattering, but is strongly affected by coexisting wind waves and swells which make the shadowing of the sea surface and the modulation of capillary waves. Our results can be explained qualitatively by considering these effects, but many truth data on the sea surface conditions and controlled experiments are needed to obtain qualitative estimations.