Low Latitude Ionospheric Electrodynamics

Fejer, Bela G.

doi:10.1007/s11214-010-9690-7

Cited by 133 publications

(98 citation statements)

References 122 publications

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“…6). This further supports our suggestion that periodic variations reported in this study at least partially can be related to lunar tides that are consistently present in the atmosphere and become strongly enhanced 128 X. H. Mo et al: Quasi-16-day periodic meridional movement of the EIA during SSW events (Pedatella and Forbes, 2010;Fejer et al, 2010;Fejer, 2011;Yamazaki, 2013). Mukhtarov et al (2010) used SABER/TIMED temperature and solar wind velocity data to identify a zonally symmetric oscillation with 14-day period in ionosphere that was considered to be of solar origin and a 18-day westwards propagating planetary wave with zonal wavenumber 1 in stratosphere and MLT region at 50 • N. Vineeth et al (2007) showed the obvious quasi-16-day periodic variation in equatorial mesopause temperature observed in the Indian sector during 2005/2006 SSW event, and their following studies showed that the obvious quasi-16-day periodic planetary wave in tropic stratosphere occurred about 60 days ahead of the 2005/2006 major SSW (Vineeth et al, 2010).…”

Section: Discussionsupporting

confidence: 90%

Quasi-16-day periodic meridional movement of the equatorial ionization anomaly

Zhang

Гончаренко

et al. 2014

Ann. Geophys.

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Abstract. Based on the daytime location of the equatorial ionization anomaly (EIA) crest derived from GPS observations at low latitude over China during the 2005-2006 stratospheric sudden warming (SSW), a quasi-16-day periodic meridional movement of EIA crest with the maximum amplitude of about 2 degrees relative to the average location of EIA crest has been revealed. In addition, periodic variations that are in phase with the meridional EIA movement are also revealed in the equatorial electrojet (EEJ) and F2 layer peak height (hmF2) over Chinese ionosonde stations Haikou and Chongqing. The quasi-16-day periodic component in Dst index is weak, and the 16-day periodic component does not exist in F10.7 index. Such large-scale periodic meridional movement of EIA crest is likely related to the globally enhanced stratospheric planetary waves coupled with anomalous stratospheric zonal wind connected with SSW. In addition, such large-scale periodic movement of EIA should be global, and can affect the ionospheric morphology around the low-latitude belt near the EIA region. Further case analysis, simulation and theoretical studies must proceed in order to understand the periodic movements of EIA connected with the different periodic atmospheric variations.

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Section: Discussionsupporting

confidence: 90%

Quasi-16-day periodic meridional movement of the equatorial ionization anomaly

Zhang

Гончаренко

et al. 2014

Ann. Geophys.

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“…Thus, there is a possibility of efficient driving of the low-to middle-latitude ionosphere by HSSs through moderate PPEFs. Another explanation is that electric field and current perturbations cause increases in magnetospheric convection and move the nighttime shielding layer equatorward, causing temporary undershielding and dawn-dusk middle-and low-latitude electric fields (see a review by Fejer, 2011). We would like to note that PPEF effects are LT dependent, with southward IMF Bz causing geoeffective eastward ionospheric electric fields on the dayside and westward on the nightside (Tsurutani et al, 2004b.…”

Section: Discussionmentioning

confidence: 96%

“…During large magnetic storms PPEF can penetrate into the ionosphere for hours (Huang et al, 2005). Observations during moderate geomagnetic activity indicate that penetration can take place for ∼one hour (see Fejer, 2011, and references therein). Verkhoglyadova et al (2011) estimated that geoeffective CIR/HSS can cause a moderate (up to 10 times lower than a superstorm) E y ∼ 5 mV m −1 with less than ∼1-2 h to create a response in the low-latitude ionosphere.…”

Section: Discussionmentioning

confidence: 99%

Variability of ionospheric TEC during solar and geomagnetic minima (2008 and 2009): external high speed stream drivers

et al. 2013

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We study solar wind–ionosphere coupling through the late declining phase/solar minimum and geomagnetic minimum phases during the last solar cycle (SC23) – 2008 and 2009. This interval was characterized by sequences of high-speed solar wind streams (HSSs). The concomitant geomagnetic response was moderate geomagnetic storms and high-intensity, long-duration continuous auroral activity (HILDCAA) events. The JPL Global Ionospheric Map (GIM) software and the GPS total electron content (TEC) database were used to calculate the vertical TEC (VTEC) and estimate daily averaged values in separate latitude and local time ranges. Our results show distinct low- and mid-latitude VTEC responses to HSSs during this interval, with the low-latitude daytime daily averaged values increasing by up to 33 TECU (annual average of ~20 TECU) near local noon (12:00 to 14:00 LT) in 2008. In 2009 during the minimum geomagnetic activity (MGA) interval, the response to HSSs was a maximum of ~30 TECU increases with a slightly lower average value than in 2008. There was a weak nighttime ionospheric response to the HSSs. A well-studied solar cycle declining phase interval, 10–22 October 2003, was analyzed for comparative purposes, with daytime low-latitude VTEC peak values of up to ~58 TECU (event average of ~55 TECU). The ionospheric VTEC changes during 2008–2009 were similar but ~60% less intense on average. There is an evidence of correlations of filtered daily averaged VTEC data with Ap index and solar wind speed. We use the infrared NO and CO2 emission data obtained with SABER on TIMED as a proxy for the radiation balance of the thermosphere. It is shown that infrared emissions increase during HSS events possibly due to increased energy input into the auroral region associated with HILDCAAs. The 2008–2009 HSS intervals were ~85% less intense than the 2003 early declining phase event, with annual averages of daily infrared NO emission power of ~ 3.3 × 1010 W and 2.7 × 1010 W in 2008 and 2009, respectively. The roles of disturbance dynamos caused by high-latitude winds (due to particle precipitation and Joule heating in the auroral zones) and of prompt penetrating electric fields (PPEFs) in the solar wind–ionosphere coupling during these intervals are discussed. A correlation between geoeffective interplanetary electric field components and HSS intervals is shown. Both PPEF and disturbance dynamo mechanisms could play important roles in solar wind–ionosphere coupling during prolonged (up to days) external driving within HILDCAA intervals

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“…The F region dynamo field is largely shorted through the E region during the day but becomes more important in the evening as the E region conductivity declines (e.g., Heelis et al, 1974;Heelis, 2004). The basic characteristics of zonal plasma drift at the equator have been presented by Fejer et al (1981Fejer et al ( , 1985 and Fejer (2011) using Jicamarca data. A typical diurnal cycle consists of westward drifts of about 50 m s −1 during the day that are solar cycle independent and solar-cycle-dependent nighttime eastward drifts that peak pre-midnight with an average value of around 130 m s −1 .…”

Section: Introductionmentioning

confidence: 99%

Topside equatorial zonal ion velocities measured by C/NOFS during rising solar activity

et al. 2014

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Abstract. The Ion Velocity Meter (IVM), a part of the Coupled Ion Neutral Dynamic Investigation (CINDI) instrument package on the Communication/Navigation Outage Forecast System (C/NOFS) spacecraft, has made over 5 yr of in situ measurements of plasma temperatures, composition, densities, and velocities in the 400-850 km altitude range of the equatorial ionosphere. These measured ion velocities are then transformed into a coordinate system with components parallel and perpendicular to the geomagnetic field allowing us to examine the zonal (horizontal and perpendicular to the geomagnetic field) component of plasma motion over the 2009-2012 interval. The general pattern of local time variation of the equatorial zonal ion velocity is well established as westward during the day and eastward during the night, with the larger nighttime velocities leading to a net ionospheric superrotation. Since the C/NOFS launch in April 2008, F10.7 cm radio fluxes have gradually increased from around 70 sfu to levels in the 130-150 sfu range. The comprehensive coverage of C/NOFS over the low-latitude ionosphere allows us to examine variations of the topside zonal ion velocity over a wide level of solar activity as well as the dependence of the zonal velocity on apex altitude (magnetic latitude), longitude, and solar local time. It was found that the zonal ion drifts show longitude dependence with the largest net eastward values in the American sector. The pre-midnight zonal drifts show definite solar activity (F10.7) dependence. The daytime drifts have a lower dependence on F10.7. The apex altitude (magnetic latitude) variations indicate a more westerly flow at higher altitudes. There is often a net topside subrotation at low F10.7 levels, perhaps indicative of a suppressed F region dynamo due to low field line-integrated conductivity and a low F region altitude at solar minimum.

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Low Latitude Ionospheric Electrodynamics

Cited by 133 publications

References 122 publications

Quasi-16-day periodic meridional movement of the equatorial ionization anomaly

Quasi-16-day periodic meridional movement of the equatorial ionization anomaly

Variability of ionospheric TEC during solar and geomagnetic minima (2008 and 2009): external high speed stream drivers

Topside equatorial zonal ion velocities measured by C/NOFS during rising solar activity

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