To study the global characteristics of field-aligned acceleration processes associated with auroral arcs, we have analyzed the particle and aurora image data obtained from the DMSP-F6 and -F7 satellites. The intensities of auroral emissions for 5577-Å, 6300-Å and N₂ (1PG) have been calculated using the observed electron fluxes and the two-stream electron transport code to show that the fluxes of precipitating electrons are sufficient to produce visible auroral arcs. Then, the density and thermal energy of these electron fluxes at magnetospheric altitude have been estimated by fitting the accelerated Maxwellian distribution function to the observed electron energy spectra and by evaluating the effect of electron heating during the acceleration. We have obtained global distributions of the field-aligned potential difference, magnetospheric electron density and thermal energy, electron heating rate during the acceleration and auroral emission intensities for magnetic quiet and active periods, respectively. It is found that the field-aligned potential difference increases as magnetospheric electron density and adiabatic field-aligned conductivity decrease, suggesting the constant-current generator for the magnetosphere-ionosphere current circuit. The magnetospheric source electrons of dayside arcs are characterized by high density and low thermal energy, particularly in the quiet period. It is suggested that accelerated electron precipitation events observed on the lower latitude side of the cusp region are connected to the LLBL, while those observed on the higher latitude side of the cusp region are connected to the plasma mantle. In the quiet period, the region of latter events expands to higher latitude region associated with the expansion of the plasma mantle into the magnetospheric lobe region. The nightside events which show low electron density and high thermal energy at the magnetospheric source region appear to have originated from the plasma sheet region. The morning side events are a mixture of high density events and low density events. We consider that the former events have a source in the LLBL or the plasma mantle, while the latter events have a source in the plasma sheet which expands to the tail flank region. These different characteristics of magnetospheric source electrons for different magnetic local time and magnetic latitude seem to produce the variety of auroral arcs on global scale.

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A paleomagnetic study was carried out on sedimentary rocks from the Middle Miocene Kukinaga Group and the Paleogene Kumage Group in Tanegashima Island off the southern extremity of Kyushu. 173 specimens were collected from 15 stratigraphic levels of the Kukinaga Group and 113 from seven horizons of the Kumage Group. After thermal and alternating field demagnetizations, characteristic magnetization directions were determined using the combined analysis of direct line-fitting and demagnetization plane data. Reliable paleomagnetic directions were isolated for 11 horizons from the Kukinaga Group. Eight of these were of reversed polarity and the remaining three from the uppermost horizons were of normal polarity. The unfolded formation-mean direction was D=331.2°, I=41.3°, and α95=9.9°. Five horizons of the Kumage Group yielded stable magnetization components of reversed polarity which, however, were not regarded as primary because of the negative tilt test. The mean paleomagnetic direction for the Kukinaga Group is deflected westward from the direction predicted using the 10Ma paleopole of Eurasia by 33.0°±10.7°. This implies that Tanegashima Island rotated counter-clockwise about 30° with respect to Eurasia and Southwest Japan since the Late Miocene, probably during the last 10Ma.

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The Tanna fault is a left lateral fault extending in the middle of the Izu Peninsula. We carried out a detailed ground magnetic survey at a grid spacing of 50 to 150m along the Tanna fault and constructed a magnetic model based on the ground survey with the help of drilling data in the Tanna basin and measurement of rock magnetism.
Total intensity distribution obtained by the ground magnetic survey represents a distinguished contrast forming relative magnetic highs in the west to the fault and lows in the east. The Tanna fault is a remarkable border terminating magnetic highs.
Drillings revealed that formations filling the Tanna basin are mainly the middle Pleistocene Taga volcanics which possess high susceptibility as a whole. A recent work suggests that the Taga volcanics were produced in normal polarity and had strong remanent magnetization. Therefore, remanent magnetization is inferred to be dominant in the total magnetization.
The magnetic contrast forms almost a north-south trend throughout the study area. The magnetic modeling using E-W profiles delineated strong normally magnetized sources of 6A/m confined to the west to the fault. Three drillings indicated that the east formations to the fault were wholly disintegrated and the west formations, by contrast, included fresh lavas. These evidences suggest that the major cause of magnetic contrast is not the difference of geologic unit but instead the weakened remanent magnetization in the east adjacent area to the fault.
Seismic reflection and shallow drillings indicate the possibility of existence of shallow wrench fault. Bending usuallly appears along a strike slip and actually several basins such as Tanna basin and the Tashiro basin exist along the fault, and some magnetic lows are supposed to be caused by sinking of volcanic layer or pull-apart movements. The striking magnetic discontinuity, on the other hand, implies that the fault surface been displaced ever since Pleistocene has always been the known Tanna fault.
In conclusion, the cause of relative magnetic lows in the east to the fault is responsible for effects of, either remanent magnetization reduced, and sinking and truncating of magnetic sources deformed, by the fault activities.

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Paleomagnetic samples were collected from sixty horizons on a sedimentary sequence of Devonian-Carboniferous boundary, Dapoushang section, Changshun County, Guizhou Province, China. There were the most complete continuous conodont zonation and evolutionary lineage from Siphonodella praesulcata to Siphonodella sulcata preserved in this section. A polarity reversal was found at 1.6m above the Devonian-Carboniferous boundary. This level falls in the upper part of duplicata Zone. The mean direction of magnetization is declination D=91.4° and inclination I=8.3°. The pole position is (0.6°S, 192.1°E).

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A reasonable baseline for the geomagnetic solar quiet daily variation (Sq) is proposed here after taking account of currents induced in the Earth. No induced currents flow in the Earth if the external fields show no time variation in the frame fixed to the Earth, because convection currents are negligible compared with the conduction currents in the induction by the Sq field. If UT variation of the external field is absent, longitudinally uniform terms of the external field cannot induce any current in the Earth, because such fields do not show time variation in the frame fixed to the Earth. Of cource, such terms can induce currents in the Earth for the real Sq field with UT variation, and in this case, it is convenient to treat the induction by the Sq field as the induction by time variation of the field in the frame fixed to the Earth. Next, we examine the amplitude ratio and phase difference of the spherical harmonics of the magnetic potential between the internal and external parts of the observed Sq field. It is found that exclusion of the time independent, internal terms significantly changes UT dependence of the amplitude ratio and phase difference, and UT variation of the internal field of P¹₂ mode is fairly well reproduced by the induction of a uniform geocentric sphere of finite conductivity, and a moment reduced roughly by 20nT.

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The Earth's motion Compton-Getting effect on the solar diurnal variation of cosmic ray intensity, has been examined by using observed data at Matsushiro underground station located at the effective vertical depth of 220m.w.e. underground (threshold energy -7.10¹⁰eV, median primary energy≥7.10¹¹eV) for the period 1980-1990. In the analysis, to eliminate the atmospheric effects on the muon intensity, the differences of the observed intensity between two-directional telescopes; the east-pointing (E-) and the west-pointing (W-) telescope, are used. Also the analysis is made for two different periods of the solar activity; the quiet period for averaged sunspot numbers Z<60 (1984-1988) and the active period for Z>60 (1980-1984 and 1988-1989). It is shown that for the quiet period, the difference E-W diurnal vector has the phase of 22.5±1.3hr LT and the amplitude of 0.030±0.007%. With a clockwise rotation of this E-W vector by the right angle, we may compare it with that expected from the Earth's motion Compton-Getting effect. It is found that the observed (0.030±0.007% in 4.5±1.3hr LT) and the expected vector (-0.021% in -6hr LT) are in fair agreement with each other. It is also found that for the active period, the observed E-W diurnal vector seems likely to show some contribution from the solar diurnal anisotropy, in addition to the Compton-Getting effect on it. This suggests that for the last solar active period the upper cut-off energy of solar diurnal anisotropy might be as high as that (several 10¹¹eV) for the threshold (-7.10¹⁰eV) of 220m.w.e. depth underground.

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Experimental scientists have indicated that an in-phase relationship between measurements of ionospheric Doppler velocity oscillations and ULF pulsations in the northward component of the geomagnetic field on the ground results from the compressional mechanism. A careful study of the theoretical models developed previously, however, shows that in low and middle geomagnetic latitudes, owing to the compressional mechanism the ionospheric Doppler velocity oscillations lead the ULF pulsations in the northward component of the geomagnetic field at ground level by 90°.

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