Ionospheric F2-Layer Semi-Annual Variation in Middle Latitude by Solar Activity

Abstract

We examine the ionospheric F2-layer electron density variation by solar activity in middle latitude by using foF2 observed at the Kokubunji ionosonde station in Japan for the period from 1997 to 2008. The semi-annual variation of foF2 shows obviously in high solar activity (2000)(2001)(2002) than low solar activity (2006)(2007)(2008). It seems that variation of geomagnetic activity by solar activity influences on the semi-annual variation of the ionospheric F2-layer electron density. According to the Lomb-Scargle periodogram analysis of foF2 and Ap index, interplanetary magnetic field (IMF) Bs (IMF Bz <0) component, solar wind speed, solar wind number density and flow pressure which influence the geomagnetic activity, we examine how the geomagnetic activity affects the ionospheric F2-layer electron density variation. We find that the semi-annual variation of daily foF2, Ap index and IMF Bs appear clearly during the high solar activity. It suggests that the semi-annual variation of geomagnetic activity, caused by Russell-McPherron effect, contributes greatly to the ionospheric F2-layer semi-annual electron density variation, except dynamical effects in the thermosphere.

Variations in Electron Content Ratio and Semi-thickness Ratio during LSA and MSA periods and some Cyclone Genesis Periods using COSMIC satellite observations

“…1. Some earlier studies have admitted that solar activity Reinisch, 2006, 2007) and geomagnetic activity (Dabas et al, 1980;Park et al, 2010;Sun et al, 2012) have obvious association with ionospheric variability. The left panel (Fig.…”

“…In Fig. 1b Reinisch, 2006, 2007;Liu et al, 2011) and geomagnetic activity (Park et al, 2010;Sun et al, 2012) presumably influence the ionospheric variability through several rigorous mechanisms.…”

Seasonal and Latitudinal Variations of the F2-Layer during Magnetic Storms

“…Using the variations of the F10.7 index between 1997 and 2008, Park et al (2010) classified 2000~2002 as the high solar activity interval, and 2006~2008 as the low solar activity interval. Fig.…”

“…Fig. 1 shows the variations of the daily averages of foF2 in Kokubunji and Hobart during the high and low solar Park et al (2010). In Fig.…”

“…Thus, the F2-layer electron density shows variations with various periods. Especially, Park et al (2010) suggested that during the high solar activity interval (2000~2002), geomagnetic activity affected the semi-annual variations of the midlatitude F2-layer. During magnetic storms, the changes in the circulation and composition of the thermosphere could also affect the ionospheric electron density.…”