The evaporation rate of H₂SO₄ in the upper aerosol region was first estimated from the vertical change of particle size distribution defined by the lidar measurements. The rate was found in the range 15-30 (H₂SO₄ molecules) cm^-3sec^-1. This results indicate that the evaporation is not negligible for the sulfate budget of lower stratosphere, and that it should be necessary to make clear the aeronomic behavior of H₂SO₄ gas above the aerosol layer.

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The relationship between the northward interplanetary magnetic field (Bz) and the reverse geomagnetic disturbance is established by using the ground-observed geomagnetic data and the satellite-observed interplanetary magnetic data. It is shown that when Bz is strong positively the reverse geomagnetic disturbance appears localized in the daytime near the geomagnetic pole in the local summer polar cap. Its ionospheric current near the geomagnetic pole flows toward the nightside i. e. reversely to the ordinary direction, its current system is a twin-vortex type, and the current vortices are located at latitudes higher than and neighbouring upon the auroral oval in the daytime. Its current is intensified there but weakened in the other regions. The time lag of the reverse geomagnetic disturbance behind the Bz variation is about 20 minutes. Its ionospheric current is considered to be due to a convection of magnetospheric plasma in the domain of the open magnetic field connected with the latitudes surrounded with the auroral oval, which is forced by the solar wind plasma.

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A method of estimation of the collision frequency in the lower ionosphere using the field intensity of a ground based LF signal observed by a rocket is described. The magnetic intensity profiles, in the ionosphere, of a ground based signal observed by a rocket and the electron density simultaneously observed at several altitudes are analyzed by iterative calculations based on a simple WKB solution. The collision frequency for mono-energetic electrons, υ_m, in the upper D and E regions was actually estimated from the altitude profile of the right handed circularly polarized component of a 40kHz ground based signal observed by means of the K-9M-53 rocket. As a result, the following relationships were obtained; υ_m=4.8×10⁵P for the upper D region and υ_m=11.0×10₅P for the E region, where P (Newton/m²) was taken from CIRA (1972).

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An analysis has been made of all archeomagnetic intensity data for the past 50, 000 years. There are 1, 175 results from different parts of the world covering the past 12, 000 years but these are heavily biased to the region of the northern hemisphere between 0° and 90°E (64% of data). The global means show a broad maximum about 6, 500 years B. P. There is no evidence from data older than 7, 000 years that a quasi-cyclic variation with period about 10⁴ years exists.
A careful analysis of 472 dipole moments covering the 2, 000 year period between 1000 A. D. and 1000 B. C. shows that they have a normal distribution with standard deviation of 19.7%. The estimate of the standard deviation of results within each 1, 000-year-interval for the past 10, 000 years is 21.2%. Analysis of the present field suggests a standard deviation of dipole moments of 17.5% would apply if the present field is representative of the past. This suggests the standard deviation due to experimental errors in archeomagnetic results is about 10%, a value that concurs with independent analysis. The ten 1, 000-year-mean dipole moments have mean 8.75×10²²Am² and estimated standard deviation 18.0% which may be attributed to dipole intensity fluctuations.
Over the period 15, 000 to 50, 000 years B. P. the earth's dipole moment was low, the 14 results available having mean value 4.44×10²²Am² with estimated standard deviation 26.5%. This is precisely the scatter to be expected from a combination of dipole intensity fluctuations of 18.0% non-dipole variations of 17.5% and experimental errors of 10% as deduced for the past 10, 000 years. The conclusion therefore is that variations in the non-dipole field always remain in the same proportion to the dipole field irrespective of its magnitude. Furthermore, the time scale of changes in the earth's dipole moment must be very much longer than has previously been supposed and must be at least 10⁵ years.

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