Coronal Mass Ejections and Problem they Cause on Earth

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Addis Ababa University


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.



Coronal Mass, Ejections, Problem, Cause on Earth