We have made various degrees of progress during the last two years in the areas covered by Topic III-6, Magnetic Storms and Substorms, including Aurora-Magnetospheric Relations. The finding of the V-potential structure above the auroral oval was certainly an important milestone in the history of magnetospheric research. The relationship between field-aligned currents and ionospheric currents has become increasingly clear during the last few years. Extensive attempts have been made to understand how the solar wind couples its energy to the magnetosphere and to find the expression for the rate of input energy from the solar wind to the magnetosphere. On the basis of this progress, a new model of the solar wind-magnetosphere relationship has begun to emerge.
The interpretation of observed magnetotail phenomena is still very confusing. Some of the problems associated with this confusion are discussed. Decisive observations to identify the basic processes associated with the “injection” of ring current particles have not been made. However, the finding of O⁺ ions in the ring current belt was an exciting event during the last two years.

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The cosmic ray north-south anisotropy arising from the heliocentric radial density gradient of cosmic rays and the interplanetary magnetic field has been studied using data for a wide range of rigidity (15-210GV in median primary rigidity) during the period 1969-1973. Two components of the anisotropy; the north-south asymmetry and the associated sidereal diurnal variation have been analyzed to reveal a three-dimensional structure of the anisotropy in space. By means of the least-squares method and using improved coupling coefficients, the direction and certain other parameters of the anisotropy have been determined.
Definite evidence has been obtained for the existence of anisotropic flow perpendicular to the ecliptic plane. The magnitude of the flow is found to be 0.081±0.021% and 0.072±0.018% at 10GV for the periods 1969-1970 and 1971-1973, respectively. It is also found that its rigidity spectrum is slightly rigidity dependent and has an upper limiting rigidity of 200GV or more. Based on the derived parameters of the anisotropy, the heliocentric radial density gradient for high rigidity cosmic rays has been estimated as a function of rigidity for 1969-1973 as (3.0±1.1)×(P/10)^-(0.7±0.2)%/AU for P≤200GV (P is rigidity in GV). The diffusion coefficient is also derived, which seems to be consistent with those so far determined.

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Time change in transfer functions for conductivity anomaly in central Japan is being monitored to detect possible electrical conductivity changes preceding earthquakes. Using geomagnetic data with a sampling interval of one minute, the transfer functions at the Kakioka Magnetic Observatory are calculated day by day. The method of analysis is based on the power spectrum analysis as developed by Everett and Hyndman. Monthly means are statistically obtained from these daily values of transfer functions. Monthly transfer functions during 40 months from January 1976 to April 1979 showed no significant changes. Small fluctuations are likely to be accounted for by seasonal changes probably originating in the external magnetic disturbance. No major earthquake activity has been reported in the vicinity of this site during this period.

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This is a report on the first ring-core type fluxgate magnetometer manufactured in Japan under a cooperative work among the three teams: Tohoku University team, Tohoku Institute of Technology team, and Tokai University team. The ring core consists of 6-81.3 Mo-permalloy tape of 10μm thick and 3mm width wound m times around a ceramic bobbin of diameter d. In order to find the best core, two identical sets of the following twelve different kinds of core were prepared: 5-79 Mo-permalloy and 6-81.3 Mo-permalloy, each with m=9, 12, and 15 turns, and d=20mm and 30mm. One set was examined by the Sendai team (Tohoku Univ. and Tohoku Inst. Tech.) and the other by the Tokai Univ. team. Each of the cores is wound by a 150-turn driving toroidal coil and packed in a 1, 100-turn pickup coil case. When a common ten-volt drive current is applied, the output voltages V for the 12 cores are in the following relations: V_6-81>V_5-79, V30>V20, and V₉>V₁₂>V₁₅. In the next step we applied drive currents with V₀=6, 8, 10, and 12 volts, and measured the input power W and the output gain G for various values of the drive frequency f₀, and found that G becomes largest for the smallest W at f₀=10kHz. Finally we constructed a fluxgate magnetometer with a 6-81.3 ring core of m=9, d=20mm, and f₀=10kHz and recorded geomagnetic variations at the Onagawa Magnetic Observatory of Tohoku University. The records were compared with simultaneous records by a commercial fluxgate magnetometer with two-core type sensors. The conclusion is that our ring-core type magnetometer is so sensitive, small, and light in comparison with the previous satellite-borne two-core type magnetometers that, in future, an improved ring-core type one can be loaded on Japanese spacecraft.

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Titanomagnetite was extracted from 43 basalt samples from Leg 37 of DSDP. The Curie temperatures and cubic cell edges were measured for these samples. When these values were plotted in the FeO-TiO₂-Fe₂O₃ ternary diagram against the contours of Curie temperature and cell edge they show a clear decrease in the Fe/Ti ratio from 4.48 for z=0, x=0.545 to 2.58 for z=0.8. This latter value is lower than that calculated for a titanomaghemite with x=0.545, z=0.8 for which Fe/Ti=3.75. The fact that other authors' results, when plotted on these same contours, yield similar results suggests that either the oxidation products do not remain single phase cation-deficient titanomagnetites or that the Curie temperature and cell edge contours require refinement before being used for quantitative identification of these properties. In any event, a standardized technique of picking Curie temperature from an experimental curve needs to be adopted by all workers.

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