123 research outputs found
Need for Morphological Study in Natural Sciences
The importance of morphological study is emphasized in natural sciences. In morphological studies, one synthesizes all the available observed facts, sequencing them in terms of causes and effects under a specific principle. It can provide not only an opportunity of breakthrough, but also the foundation of a significant theoretical research. It is the stage where creativity and innovativeness can most clearly be displayed
Syntheses, Creativity and Paradigm Change
In this short paper, I emphasized that creativity in research is best demonstrated by a synthesis effort of observed facts, which could bring a paradigm change and produce a step-wise progress (“breakthrough”) in science
Dispersion Relation of Magneto-hydronynamic Waves in the Ionosphere and its Application to Shock Wave
Effects of the Variation of the Temperature Gradient in the Upper Atmosphere on the Formation of the Ionospheric Layers
The Explosive Characteristics of the Aurora: The Electric Current Line Approach
The aurora shows explosive activities a few times in 24 h on a moderately active day. This specific phenomenon is called the auroral substorm, which consists of the growth, expansion, and recovery phases; the explosive activities occur during the expansion phase. As an introduction, the explosive activities of the aurora are morphologically described on the basis of ground-based all-sky and satellite images. In terms of theoretical understanding, the processes for the explosive activities have been considered almost exclusively in terms of “the magnetic field line approach” in the past, including the process of magnetic reconnection. Instead, in this paper, we consider the substorm processes in terms of “the electric current line approach.” This approach requires that the whole process of auroral substorms should be considered as a chain of processes, which consists of power supply (dynamo), transmission (currents/circuits), and dissipation (auroral substorms). An increased power of the solar wind-magnetosphere dynamo intensifies (to the level of 1011w = 5 × 1018 erg/s), the electric current mainly in the main body (just outside of the ring current) of the magnetosphere increases, resulting in accumulating energy in its inductive circuit (≈6 Re), and inflation of the magnetosphere. When the accumulated energy reaches about 5 × 1015 J (= 5 × 1022 ergs), the magnetosphere tends to become unstable (because of current instabilities). As the current intensity is reduced as a result, the magnetosphere is deflated. It is suggested that it is in this deflation process, during which the accumulated energy is unloaded, and an earthward electric field (5–50 mV/m) is produced on the equatorial plane, establishing the unloading current system (the UL current system), which is responsible for the unloading expansion phase, including the most characteristic features of the expansion phase, such as the poleward advance of the aurora and the development of the auroral electrojet. The electric current approach is rather new and needs much more effort to develop
A study of magnetic storms and auroras
New notations for magnetic disturbance fields are proposed, based on
the theoretical consideration of the electric current systems by which
they are produced.
A typical magnetic storm begins suddenly when the onrush of the front
of the solar gas is halted by the earth's magnetic field. This effect
(DCF field) is most markedly observed as a sudden increase of the horizontal
component of the earth's field (the storm sudden commencement,
abbreviated to ssc)— like a step function. In many cases, however, the
change of the field during the ssc is more complicated, and different at
different places. Such a complexity superposed on the simple increase
(DCF) is ascribed to a complicated current system generated in the polar
ionosphere (DP current). It is found that the changes of electromagnetic
conditions in the polar regions are communicated, without delay, to lower
latitudes, even down to the equatorial regions. It is inferred that the
equatorial jet is affected by such a change and produces the abnormal
enhancement of ssc along the magnetic dip equator.
From the extensive analysis of several magnetic storms that occurred
during the IGY and IGC, it is suggested that the capture of the solar
particles in the outer geomagnetic field occurs when irregularities
(containing tangled magnetic fields and high energy protons) embedded in
the solar stream, impinge on the earth.. Thus the development of a magnetic
storm depends on the distribution of such irregularities in the stream.
The motions and resulting currents and magnetic fields of such "trapped"
solar particles are studied in detail for a special model. It is inferred
that a large decrease (DR field) must follow the initial increase; it is
ascribed to the ring current produced by such motion of solar protons oi
energy of order 500 Kev. It is proposed that during the storm there
appears a transient 'storm-time1 belt well outside the outer radiation
belt.
It is predicted that the earth's magnetic field is reversed in
limited regions when the ring current is appreciably enhanced. This
involves the formation of neutral lines there. These may be of two
kinds, called X lines or 0 lines according as they are crossed or encircled
by magnetic lines of force. These may be entirely separated or
may be joined to form a loop, called an OX loop. It is shown that one
of them, the X line, which is connected with the auroral ionosphere by
the lines of force, could be the proximate source of th<e particles that
produce the aurora polaris. By postulating the existence of such X-type
neutral lines at about 6 earth radii, an explanation is obtained of the
detailed morphology of the aurora. This includes the auroral zones and
their changes, the nighttime peak occurrence of auroras, their thin
ribbon-like structure and their multiplicity, their diffuse and active
forms and the transition between them (break-up) the required electron
and proton flux, and the ray and wavy structures.
Among the most important phenomena associated with the sudden change
of the aurora from the diffuse to the active form are the simultaneous
appearance of the auroral electrojet and the resulting polar magnetic
disturbances (DP sub-storms). Several typical DP sub-storms are studied
in detail. It is concluded that a westward auroral jet is produced by a
southward electric field. It is shown that an instability of the sheetbeam
issuing from along the X-type neutral line can produce a southward
electric field of the required intensity. The southward electric field
produces an eastward motion of the electrons in the ionosphere. This may
be identified with the eastward motion of an active aurora and with the
westward auroral electrojet.
Besides such large changes- of the field, there often appear various
quasi-sinusoidal changes of the field, much less intense. They are
supposed to be hydromagnetic waves, some of which are generated in the
outer atmosphere and propagated through the ionosphere, where a certain
amount of their energy is dissipated. It is concluded however that Such
a dissipation is not sufficient to produce any appreciable heating of the
ionosphere.Chapter I The electromagnetic environment of the earth : The solar system in the Galaxy ; The sun and the interplanetary space ; The outer atmosphere, the Van Allen radiation belts and the ionosphere ; The earth’s permanent magnetic field ; Introduction to geomagnetic storms and auroras ; The analysis of the earth’s magnetic field – Chapter II The sudden commencement of magnetic storms : Introduction ; The studies of Sc and Si at individual observations ; A theory of the Sc of magnetic storms ; Transmission of the Sc from the inner boundary of the solar steam to the earth’s surface ; The sudden commencement DP currents – Chapter III The ring current and the van allen radiation belts : Introduction ; The motion of charged particles in the earth’s dipole magnetic field ; Electric currents in an ionized gas (general formulae) ; The steady ring current in a dipole field ; The magnetic field produced by the ring current ; The main phase of magnetic storms ; The ring current belt ; Discussion – Chapter IV A neural line discharge theory of the aurora Polaris : Introduction ; The formation of a neutral line ; The motions of charged particles close to a neutral line ; The auroral zones ; Particle injection associated with arcs ; Rayed arcs ; Instabilities of auroras – Chapter V Polar magnetic disturbances : Introduction ; The polar magnetic disturbances of 5 to 6 December 1958 (College, Alaska) ; The polar magnetic disturbances of 29 September 1957 (Worldwide) ; The polar magnetic disturbances of 23 September
1957 ; The eastward motion of auroras and the electric field of polar magnetic disturbances ; The origin of the electric field of polarmagnetic disturbances – Chapter VI Hydromagnetic waves in the ionosphere : Introduction ; Ionospheric heating by hydromagnetic waves connected with geomagnetic micropulsations – Acknowledgements -- ReferencesYe
The basic solar wind speed distribution and its sunspot cycle variations
In this paper, it is suggested that the latitudinal solar wind speed observed by the Ulysses spacecraft during the lowest solar activity (when both the ecliptic and magnetic equators coincide) may be identified as the basic speed distribution throughout the solar cycle. We demonstrate this suggestion by rotating this particular Ulysses distribution counterclockwise up to 70° in accordance with the rotation of the equivalent dipole axis during active periods of the cycle. The corresponding magnetic equator in the Carrington map latitude-longitude (27 days) becomes quasi-sinusoidal with respect to the ecliptic equator. The quasi-sinusoidal magnetic equator on the Carrington map and its modification associated with the degree of sunspot activities can explain the two high speed peaks (750–800 km/s) and the two lowest speed (350 km/s) during 27-day solar rotation periods, most clearly recognizable after the sunspot peak period. Thus, it may be not necessary to consider coronal holes or open regions as the source of high speed streams. In fact, this particular (lowest solar activity) Ulysses distribution may represent the speed distribution pattern by the basic generation process of the solar wind itself
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