Abstract
This paper investigates solar wind repartition through four classes of solar events: (1) one class of quiet days (QD) caused by slow solar wind (V< 450 km/s), and three disturbed activities, where V ≥ 450 km/s, (2) recurrent wind (RW), (3) shock wind (SW), (4) fluctuating wind (FW). RW class is characterized by recurrent high solar wind extended on several solar rotations. SW class is caused by CMEs events. FW class is formed with all the un-identified events in the previous well-organized classes. We achieve this classification by using pixel diagram built with solar wind velocity. This includes the sunspot cycle 23 and the early ascending phase of sunspot cycle 24 (2009-2010). Quiet days occurred most frequently during the increasing phase of sunspot cycle (35%), while recurrent wind activity was present at solar maximum around 20% of the time, with the largest occurrence (49%) on the declining phase of the sunspot cycle. The largest percentage of shock wind events (43%) occurs around the maximum phase while fluctuating events stay fairly during the entire sunspot cycle (~27%). We also discuss current ideas about the interaction between solar wind and geomagnetic activity over sunspot cycle 23 and the early ascending phase of sunspot cycle 24. Key words: Solar wind, geomagnetic activity, solar cycle, sunspot cycle.
Highlights
Geomagnetic activity may be defined as short-term variation in Earth’s magnetic field induced by change in solar magnetic field
In pursuance of the strong correlation between the aa index and solar wind established by Svalgaard (1977) and the fact that 91.5% of the time geomagnetic activity is generated by corotating wind sources (Simon and Legrand, 1987), we are investigating in this paper the distribution of solar wind speed through diagrams displaying solar wind speed as a function of time over Bartels rotations and discuss each solar wind structure effects level on geomagnetic activity during sunspot cycle phases
The temporal occurrence of each type of geomagnetic activity through a solar cycle is well-known and many studies outlining the close link between solar wind and geomagnetic events have been done by several authors (Legrand and Simon, 1989; Ouattara and Mazaudier, 2009; Richardson and Cane, 2012; Zerbo et al, 2012; Holappa et al, 2014)
Summary
Geomagnetic activity may be defined as short-term variation in Earth’s magnetic field induced by change in solar magnetic field. More recent studies (Legrand and Simon, 1989; Richardson et al, 2000, 2002; Zerbo et al, 2012) show that these perturbations can be organized into quiet, recurrent, shock, and fluctuating/ unclear geomagnetic activity classes. These classes are defined using Bartels 27-days solar rotation based on geomagnetic index aa as a function of time to give the measure of the geoeffectiveness of solar wind events. In pursuance of the strong correlation between the aa index and solar wind established by Svalgaard (1977) and the fact that 91.5% of the time geomagnetic activity is generated by corotating wind sources (Simon and Legrand, 1987), we are investigating in this paper the distribution of solar wind speed through diagrams displaying solar wind speed as a function of time over Bartels rotations and discuss each solar wind structure effects level on geomagnetic activity during sunspot cycle phases
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
