Coronal Mass Ejections and Problem they Cause on Earth
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Date
2020-10-10
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Addis Ababa University
Abstract
In this thesis work we study coronal mass ejections (CMEs) and their impact on
earth with emphases on solar active regions, geomagnetic storms and geomagnetically
induced current densities. Based on present concept, strong southward
interplanetary magnetic field and high-speed of interplanetary CMEs are important
main drivers of severe geomagnetic storms that lead to geomagnetically induced
currents. These can cause powerful effect on the magnetosphere to ground and on
the modern technologies, such as power transmissions, satellites and spacecrafts,
positioning and navigation systems, oil and gas pipe lines and harmful to astronauts
in space. Therefore, primarly understanding for the prime drivers of the above
effects in general is important, to predict space-weather and CME impacts on
earth. We correlated sunspot cycle, CMEs and geomagnetic storms using yearly
sunspot-index number data in the years of 1950–2009 and disturbance storm time
index (Dst-index) data obtained from the WDC of Kyoto, Japan on March 12–
14, 1989 and on October 29–31, 2003 to November 19–21, 2003. The results
indicates that major CMEs can cause severe geomagnetic storms as on March
13–14, 1989 with Dst-index of _ ��589nT during sunspot cycle 22 (1986–1996)
of maximum sunspot number. On the other hand, during October 29–31, 2003
geomagnetic storm of minimum peak Dst-index of _ ��400nT is correlated with
the declining phase of sunspot number in cycle 23 (1996–2008). Moreover, we
suggested that severe geomagnetic storms which affects modern technologies can
be occured during the declining sunspot number (in the way of recovery phase) as
well as during the maximum sunspot number (storm main phase). Finally, we
computed sample of ground current densities using plane wave method, based
on magnetic diffusion equation. We found that maximum amplitudes of this at
the ground. Then, they all show an exponentially decrease in the intensity of
current density values towards the earth center. Furthermore, we suggested that
such east-west current densities during major CMEs can cause problem on power
transmissions which are connected to area of high ground resistivity.
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Keywords
Coronal Mass, Ejections, Problem, Cause on Earth