The process of intrusion of stratospheric ozone into the troposphere, observed from an aircraft, is analysed with the use of routine aerological data. Stratospheric ozone is transported downward through the polar jet stream frontal zone to an altitude of 3 km. Such transport is supported by the distributions of the potential vorticity, the water vapor and CF2Cl2 distributions. The ozone in the troposphere seems to be diffused near the bottom of the frontal layer. The estimated magnitude of the Richardson number suggests that such diffusive mixing is much stronger at an altitude of 5 km than at 7 km in this case. The power spectral density of the ozone variations observed along the flight course shows that the turbulent motions with wavelengths of 5 to 20 km are important.
Tritium concentration in water vapor in the air near the surface and in the precipitation at Tokyo was measured during the period from 9 August to 20 November in 1974. From August to the middle of October, tritium mixing ratios in the surface air had relatively higher values except those in air masses which were associated with a typhoon. The mixing ratios of tritium in the air decreased abruptly at the middle of October, which indicates the decrease of tritium influx from aloft. These data exhibit the salient feature that variations in tritium concentration in TR are linear to the reciprocal of the content of water vapor during each period. Tritium concentrations in vapor and rain water collected simultaneously show nearly equal values. One of the reasons for the good correlation of tritium concentration between falling drops and ambient air is considered to be the result of the rapid isotopic exchange.
A method of enhancing the natural period of an electro-magnetic seismometer is presented. The output signal of the detector coil of a transducer is amplified and fed to the feedback coil through a current-differentiation circuit. By this arrangement, the force of inertia is given to the pendulum, and the moment of inertia of the pendulum is effectively increased, lengthening the natural period of the seismometer. To make a long-period seismometer which is useful for volcano observation, the above method was applied to the electro-magnetic seismometer which has a pendulum of 2-second period. The new seismometer has 10-second period and not only is portable but also gives high performance in the moderate operating temperature ranges. The constants of this seismometer are as follows:
The seismometer thus devised seems very useful to permanent observation, and it has been operated for volcano observation at the Asosan Weather Station since October, 1982.