The Sun Together With The Earth: Interactions During Geomagnetic Storms

by Chukwuma Anoruo

The land of solar-terrestrial interactions, the interplay betwixt the Dominicus in addition to other planetary bodies inwards the solar system, is a fascinating expanse of research. My noesis well-nigh this discipline every bit a doctoral pupil straight off spans iii years. The trouble of my enquiry delves into the report of major disturbances (geomagnetic storms) of the Earth’s magnetic part (extending from the Earth’s interior out into space) that occur whenever at that spot is a rattling efficient central of release energy from the solar current of air into the infinite surroundings surrounding the Earth. Geomagnetic storms bring unique characteristics, in addition to no 2 storms bring the same behavior. Here, I elbow grease to report distinctive characteristics of storms’ strength on the electron content of the ionosphere in addition to its trans-ionospheric disturbance of radio signal propagation. This commonly has a heavy impact on the Global Positioning System (GPS), causing signal errors in addition to infinite weather condition perturbation. This activity relative to tempest strength causes extra drag on satellites, which modifies the path of radio signals creating errors inwards positioning information provided past times GPS. It every bit good disrupts navigation systems in addition to creates harmful, geomagnetically induced currents inwards the mightiness grid. Studying this discipline is essential for airports to sympathize periods of security in addition to for communication amongst pilots during flights. A full general sentiment of the physics of this concept is explained hither for a non-expert audience.

Introduction

The solar-terrestrial interaction exactly refers to the Earth’s part that is influenced past times the physical conditions of the solar interior. Figure 1 shows a diagram of solar-terrestrial interaction. This part is called the Ionosphere in addition to it contains a large total of electrons that are able to reverberate radio signals [1]. The disturbance of this part is called ionospheric disturbance which so causes the Earth’s geomagnetic storms. This disturbance results from streams of energetic particles consisting of electrons in addition to ions (plasma) carried past times solar current of air into the Earth’s magnetosphere (the magnetic field). The solar current of air originates from the Sun’s coronal holes every bit a outcome of expansion of the solar atmosphere when the land is open. This current of air propagates amongst a velocity of 400 kilometers per second, hitting the Earth’s atmosphere in addition to causing perturbation of the Earth’s geomagnetic land [2]. The ionospheric disturbance results inwards instability of the ionosphere, causing the bending of radio signals. This is exactly because the ionized electrons impact propagation of radio signals. This plane of ionization is dependent upon fourth dimension of the day, flavour in addition to latitude [3].

Figure 1. Solar-terrestrial interaction

The parameter widely used to report the score of ionospheric disturbance during geomagnetic storms is the full electron content (TEC) [4]. TEC is an integrated shape of the electron expose density that exists betwixt the satellite in addition to the footing receiver. The electron density is the stair out of the probability of an electron beingness acquaint at a specific location. The low, middle in addition to high latitudes of the ionosphere sense dissimilar responses during geomagnetic storms. Recent advances inwards satellite applied scientific discipline bring made pregnant improvements inwards using TEC to report ionospheric variability [3]. Its measuring has played a pregnant purpose inwards determining the delay that is commonly experienced inwards the radio signal transmitted from a GPS satellite to the footing receiver.

Physics of solar-terrestrial interaction

The disturbance tempest fourth dimension (Dst) measured inwards nano Tesla (nT) is a major hourly index that is used inwards defining in addition to quantifying the strength of a storm. It monitors the score of tempest strength caused every bit the outcome of geomagnetic land disturbance, which signifies the total of ions beingness injected. The collision of these ions amongst electrons causes electrical excitation of the electron and, consequently, an increment inwards TEC. This is to a greater extent than frequent during a solar maximum - the active menstruum of the Sun. Since disturbance of Earth’s magnetosphere is associated amongst geomagnetic storms, they are categorized amongst a negative intensity of Dst index every bit seen inwards Table 1.

Type of storm	Dst hit (nT)
Weak	>-50
Moderate	-100 to -50
Intense	-250 to -100
Severe	<-250

Table 1. Classification of geomagnetic storms amongst dissimilar Dst ranges [5]

Figure 2 indicates a schematic diagram of August 1998 storm-like variation inwards the Dst index featuring a typical geomagnetic storm. The Dst ranges from negative to positive values. During intense storms Dst decreases in addition to increases during calm days.

Figure 2. Schematic diagram of tempest strength

At solar maximum, high energetic particles composed of charged plasma from the Earth’s magnetosphere are forced into the Earth’s atmosphere past times the solar wind. The solar atmosphere is made upwardly of iii layers: a) the photosphere, b) the chromosphere, in addition to c) the corona. This is shown inwards Figure 3. The photosphere represents the laissez passer on of the convection zone, where most sunlight is emitted. In this layer at that spot is evidence of dark spots, called sunspots, which are surrounded past times brighter areas known every bit the active regions. The chromosphere in addition to corona prevarication higher upwardly the photosphere. In the corona, at that spot are areas that are colder, thence darker, in addition to bring depression density plasma because of their lower release energy in addition to gas levels. Such areas are known every bit coronal holes. In the coronal holes, the magnetic land is open, in addition to through it, the solar current of air propagates outward. On unopen to occasions, huge erupting bubbles known every bit coronal volume ejections (CMEs) are observed every bit a outcome of an eruption. At this fourth dimension solar wind, originating from the coronal holes where the magnetic land is open, propagates energetic particles amongst a speed of 400 km/s into the Earth’s atmosphere.

Figure 3. The solar atmosphere

The Interplanetary Magnetic Field (IMF) is a weak field, varying inwards strength close the Earth. It is the hateful bird of the apparent path inwards the Earth’s part that the Dominicus follows over the course of pedagogy of i year. Furthermore, it is part of the Sun’s magnetic land carried past times the solar wind. The International Monetary Fund is the principal machinery of solar-terrestrial interaction in addition to regulates the interstellar energetic particle penetration rate. This is the charge per unit of measurement at which energetic particles penetrate the Earth’s magnetic field. The kinetic describe per unit of measurement area of solar current of air modifies the outer part of the Earth’s magnetic land past times compressing it — this compression occurs mainly at 24-hour interval time, but tin give notice sometimes persist until the night. The orientation of the International Monetary Fund is a major contributing constituent to the entrance of energetic particles from the Sun. The International Monetary Fund is a vector quantity amongst iii axes, of which the vertical axis (Bz) is of import for auroral activity. The principal stage of geomagnetic storms occurs when the International Monetary Fund drifts southward along the Bz axis, patch a northward shift coincides amongst the halt of the storm. 

Summary in addition to conclusion

The Earth’s magnetic land protects it from unsafe radiations in addition to high release energy plasma from the Sun. However, at that spot is ever unopen to part of the plasma in addition to radiations that is able to penetrate through the magnetic land barrier, in addition to this oftentimes leads to magnetic disturbances. The magnetic land of the footing becomes disturbed when hitting past times energetic particles emitted from the Dominicus resulting from CME. The actual total of this depression does non exclusively depend on tempest severity but every bit good duration. These magnetic disturbances impact communication in addition to navigation systems and, when severe, may Pb to a full blackout. Geomagnetic storms are to a greater extent than frequent during the active menstruum of the Sun. At the minimum solar activity period, the land is at its quietest. The departure of TEC during disturbed in addition to repose times gives the actual TEC value which is to a greater extent than valid for determining tempest strength. A reliable in addition to accurate representation of the ionosphere is essential inwards social club to sympathize the impact of storms in addition to how they impact GPS applications. The ask to sympathize the demeanour of the Earth’s magnetic field, its beginning in addition to variation, is becoming ever to a greater extent than important.

Chukwuma Anoruo
Department of Physics in addition to Astronomy, University of Nigeria, Nsukka, Nigeria


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References


[1] Garner, T. W., Gaussiran, T. L., Tolman, B. W., Harris, R. B., Calfas, R. S., Gallagher, H. (2008). Total electron content measurements inwards ionospheric physics. Adv. Space Res 42: 720–726.
[2] Lockwood M., Chambodut A., Barnard L.A., Owens M.J., Clarke E., Mendel V., (2018), A homogeneous aa index, secular variation, Journal of Space Weather Space Climate, 8, 27-53.
[3] Kenpankho, P., Supnithi, P., Tsugawa, T & Maruyama, T. (2011). Variations of ionospheric slab thickness observations of Chumphon equatorial magnetic location. footing PlanetsSpace 63:359-364.
[4] Oron, S., D'ujanga, F. M. &Senyonga, T. (2013).Ionospheric TEC variations during the ascending solar activity stage at an equatorial station. Uganda. Indian Journal of Radio & Space Physics 42:7-17.
[5] Gonzalez,W.D., Joselyn, J.A., Kamide, Y. H., Kroehl, W., Rostoker, G., Tsurutani, B.T., Vasyliunas, V.M. (1994). What is a geomagnetic storm? Journal of Geophysical Research 99:5771–5792.
[6] Buonsanto, M. J. (1999). Ionospheric storms – A review. Space Science Review 88, 563–601.