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Information Journal Paper

Title

THE EFFECT OF MAGNETIC STORMS ON IONOSPHERIC LAYERS

Pages

  1-8

Abstract

 Dynamic processes in the sun, such as solar flares, transmit plasma of charged particles, especially electron and proton, and associated fields into the earth's surroundings that cause geomagnetic disturbances on the earth's surface, called MAGNETIC STORMS. On magnetic quiet days, moving charged particles, called solar wind, can restrictedly enter into the earth's atmosphere in the Polar Regions. On disturbed magnetic days, more particles at high speed can influence the earth's atmosphere and affect the ionospheric layers.During a magnetic storm, energy enters into the ionosphere at high latitudes that can change some thermospheric parameters such as atomic and molecular composition, temperature and circulation. Composition changes directly affect the ELECTRON CONCENTRATION in the F2 layer, and circulation propagates the warm gas into the lower latitudes. Increasing thermospheric temperature expands the F2 layer and then the layer establishes at higher altitude and the ELECTRON CONCENTRATION decreases (Campbell, 1997). The most intensive disturbances of the ionospheric layers occur during magnetic disturbances. They have a catastrophic effect in the auroral zone and the application of the normal laws is impossible. During such a disturbance, corpuscular emission, originating on the sun penetrates the atmosphere of the earth, usually in a belt between 55° to 80° of geomagnetic latitude. It generally hits the night side of the earth. Chapman and Ferraro (1930) have shown that the corpuscular emission must consist of an equal number of charges of both signs and therefore appear in general as conducting but uncharged. A magnetic disturbance in the auroral zone begins usually in the evening, with oscillations of the magnetic field. Simultaneously, aurorae borealis occur which are usually band-shaped. Strong reflections from the E-level appear in a wide frequency range often attaining 10 MHz. F-reflections do not occur since the auroral E-layer blankets the higher layers.In the course of the disturbances, the penetrating corpuscular emission often becomes harder, ionization shifts downward and the damping increases. For periods of a few minutes no reflections at all can be observed (polar blackout). Such conditions may predominate for many hours, especially during very serious disturbances. The reflections from the E-level also cease in the case of less serious disturbances shortly after midnight due to the decrease in corpuscular emission. The auroral lights diminish simultaneously and then cease entirely. During this second phase of the disturbance which lasts at least until dawn, no echoes at all can be observed. The E-reflections stop with the cessation of corpuscular emission; F-echoes also do not exist anymore as this layer was dissolved in the course of the disturbance (Rawer, 1956). In the Polar Regions the main effects of ionospheric storms are the increases in the ELECTRON CONCENTRATIONs in the E and D regions: they can be understood in outline in terms of the energetic electrons that also produce the aurora. At lower latitudes, however, the changes in the D region take a different form and there are conspicuous changes in the F layer.A storm usually results in significant changes in the F layer all over the world; at most latitudes the concentration of electrons is decreased, although, within a few degrees of the geomagnetic equator, it is often increased. These changes have not been properly explained. The decrease is the most surprising. One type of explanation ascribes it to an increase in the rate of loss of electrons. In the F region that loss involves reactions of the type O+N2®N+2+, with a rate k[N2][O+]: this rate could be increased during a storm either because k increases or because [N2] increases. Laboratory measurements suggest that k increases with temperature and since the temperature is known to increase during a storm the decrease of ELECTRON CONCENTRATION would be explained.Those who ascribe the storm phenomenon to an increase in the concentration of molecular nitrogen suggest that during a storm the entry of particles into the low polar ionosphere excites gravity waves that then travel into the F region at lower latitudes where they mix the atmospheric constituents.Still another suggestion is that the modification of the ionospheric current system that shows itself as the polar electrojet is accompanied by an electric field that extends into the F region at lower latitudes and there causes the ionospheric plasma to move downwards to levels where the rate of loss is greater. To explain an increase in the F region electron content, of the kind that is often observed near the equator during storms, it has been suggested that at those times the ionosphere is moved upwards to places where the rate of loss of electrons is smaller. The movement might be caused by the electric field of the dynamo below, so that the F region acts like an atmospheric motor. It might also be caused by a wind in the neutral air, blowing from the poles towards the equator, so as to move the ionization upwards along the sloping lines of force (Ratcliff, 1972).

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    APA: Copy

    SHIRZADITABAR, FARZAD, & HOSSEINZADEH GOUYA, N.. (2008). THE EFFECT OF MAGNETIC STORMS ON IONOSPHERIC LAYERS. JOURNAL OF THE EARTH AND SPACE PHYSICS, 34(1), 1-8. SID. https://sid.ir/paper/80355/en

    Vancouver: Copy

    SHIRZADITABAR FARZAD, HOSSEINZADEH GOUYA N.. THE EFFECT OF MAGNETIC STORMS ON IONOSPHERIC LAYERS. JOURNAL OF THE EARTH AND SPACE PHYSICS[Internet]. 2008;34(1):1-8. Available from: https://sid.ir/paper/80355/en

    IEEE: Copy

    FARZAD SHIRZADITABAR, and N. HOSSEINZADEH GOUYA, “THE EFFECT OF MAGNETIC STORMS ON IONOSPHERIC LAYERS,” JOURNAL OF THE EARTH AND SPACE PHYSICS, vol. 34, no. 1, pp. 1–8, 2008, [Online]. Available: https://sid.ir/paper/80355/en

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    مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
    مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
    مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
    مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
    مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
    مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
    مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
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