Variations of IMF Cone Angle and IMF Clock Angle on Solar Cycles and Geomagnetic Storms Afia Izza Fadiyah (a*), Dhani Herdiwijaya (b)
Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology
Abstract
Interplanetary magnetic field (IMF) carried by solar wind and rooted at corona. Variations of IMF depend on solar surface activities, e.g. sunspots. Moreover, solar magnetic storms are connected by IMF. IMF parameters, sunspot number, and geomagnetic index are downloaded from OMNIWeb which the data were obtained from several spacecrafts in geocentric and lagrange orbits. Solar cycles are measured in terms of variations in the number of sunspots and its polarity. Both magnetic events of IMF and sunspots indicate the relation between solar cycles and IMF orientation which is clock angle and cone angle. IMF also interact with magnetosphere and it can cause the geomagnetic storms.
Cone angle and clock angle are derived from IMF components on X-axis, Y-axis, and Z-axis. Their frequency distribution charts on each solar cycle of 20 to 24 and its maximum phase and minimum phase are the key point for the analysis. The plot of clock angle to Dst index as a geomagnetic index for each solar cycle were also derived.
Based on the analysis, solar cycles are indicated gives an impact to the magnitude of each IMF components. It makes the peak of the charts shifted from minimum phase to maximum phase. Other than that, the reconnection in magnetopause mostly occur when the the clock angle between 140 deg-252 deg or when the clock angle directions are southward. But the 23rd solar cycle shows the northward clock angle can also cause an extreme geomagnetic storms.
Keywords: Interplanetary Magnetic Field, Cone Angle, Clock Angle, Geomagnetic Index
