Causal relationship between Sunspot numbers and geomagnetic Storms during 23 and 24 solar cycle Periods

Abstract

The study presents the causal relationship between the sunspot numbers (SSN) and geomagnetic storms(GMSs) from 1996 to 2016, which is the span of solar cycles 23 and 24. Sunspots are regions at the surface of the sun with an intense magnetic field and a lower temperature than the rest of the photosphere. It provides the first indications of the possibility of solar eruptions that precede GMSs on the Earth. The data used to study the causal relationship between SSNs and GMSs contains sunspot numbers, the Dst-index, and Halo coronal mass ejections. The sunspot numbers (SSNs) are used as basic parameters for knowing the behavior of solar activity and are obtained from the Omni website. The Dst-index was extracted from the World Data Center for Geomagnetism, Tokyo, Japan, while the data on the Halo CME number came from observations made by the Large-Angle and Spectrometric Coronagraph (LASCO) on board the Solar and Heliospheric Observatory Mission (SOHO). The causal relationship between the sunspot numbers and geomagnetic storms of the years 1996 - 2016 was analyzed using the correlation of SSN with GMS and CMEs and GMS with CMEs. The results of the analysis indicated that the yearly occurrence rate of geomagnetic storms was strongly correlated with the occurrence rate of sunspot numbers, but that the two were not simultaneous across the years and did not follow a specific pattern. Moreover, from the analysis between GMSs and CMEs, we observed that the occurrence rate of GMSs followed exactly the yearly occurrernce of Halo CMEs, which concluded that Halo CMEs were responsible for the occurrence of GMSs.