Equatorial ionization anomaly response to lunar phase and stratospheric sudden warming

AbstractThis study examines the ionosphere response to gravitational forces of the lunar phase and dynamical disturbances of the stratospheric sudden warmings (SSWs). The total electron content (TEC) of global ionosphere maps is employed to examine responses of the equatorial ionization anomaly (EIA) crests to lunar phases and twelve SSW events during 2000–2013. The most prominent feature in the ionosphere is the EIA, characterized by two enhanced TEC crests at low latitudes straddling the magnetic equator, which can be used to observe ionospheric plasma dynamics and structures. Results show that the EIA crest appearance time on new/full moons (first/third quarters) leads (lags) that of the overall 14-year average, which causes a pattern of TEC morning enhancements (suppressions) and afternoon suppressions (enhancements). A statistical analysis shows that SSWs can also significantly cause the early appearance of EIA crests, regardless of the lunar phase. Thus, both lunar phase and SSWs can significantly modulate the appearance time of EIA crest and ionospheric plasma dynamics and structures.

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Observations of equatorial ionization anomaly over Africa and Middle East during a year of deep minimum

Annales Geophysicae ◽

10.5194/angeo-35-123-2017 ◽

2017 ◽

Vol 35 (1) ◽

pp. 123-132 ◽

Cited By ~ 7

Author(s):

Olawale Bolaji ◽

Oluwafisayo Owolabi ◽

Elijah Falayi ◽

Emmanuel Jimoh ◽

Afolabi Kotoye ◽

...

Keyword(s):

Middle East ◽

Continuity Equation ◽

Equatorial Electrojet ◽

Data Acquisition System ◽

Magnetic Data ◽

Electron Content ◽

Deep Minimum ◽

Total Electron ◽

Equatorial Ionization Anomaly ◽

Low Latitudes

Abstract. In this work, we investigated the veracity of an ion continuity equation in controlling equatorial ionization anomaly (EIA) morphology using total electron content (TEC) of 22 GPS receivers and three ground-based magnetometers (Magnetic Data Acquisition System, MAGDAS) over Africa and the Middle East (Africa–Middle East) during the quietest periods. Apart from further confirmation of the roles of equatorial electrojet (EEJ) and integrated equatorial electrojet (IEEJ) in determining hemispheric extent of EIA crest over higher latitudes, we found some additional roles played by thermospheric meridional neutral wind. Interestingly, the simultaneous observations of EIA crests in both hemispheres of Africa–Middle East showed different morphology compared to that reported over Asia. We also observed interesting latitudinal twin EIA crests domiciled at the low latitudes of the Northern Hemisphere. Our results further showed that weak EEJ strength associated with counter electrojet (CEJ) during sunrise hours could also trigger twin EIA crests over higher latitudes.

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Strong equatorial plasma bubble associated with prominent TEC enhancement observed at mid-latitude ionosphere under the quiescent condition

10.5194/egusphere-egu21-3832 ◽

2021 ◽

Author(s):

Fuqing Huang ◽

Jiuhou Lei ◽

Chao Xiong

Keyword(s):

Electron Density ◽

Electron Content ◽

Radio Waves ◽

Plasma Bubble ◽

Total Electron ◽

Middle Latitudes ◽

Multiple Observations ◽

Equatorial Plasma Bubbles ◽

Low Latitudes

<p>Equatorial plasma bubbles (EPBs) are typically ionospheric irregularities that frequently occur at the low latitudes and equatorial regions, which can significantly affect the propagation of radio waves. In this study, we reported a unique strong EPB that happened at middle latitudes over the Asian sector during the quiescent period. The multiple observations including total electron content (TEC) from Beidou geostationary satellites and GPS, ionosondes, in-situ electron density from SWARM and meteor radar are used to explore the characteristic and mechanism of the observed EPB. The unique strong EPB was associated with great nighttime TEC/electron density enhancement at the middle latitudes, which moves toward eastward. The potential physical processes of the observed EPB are also discussed.</p>

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Time delay and duration of ionospheric total electron content responses to geomagnetic disturbances

Annales Geophysicae ◽

10.5194/angeo-28-795-2010 ◽

2010 ◽

Vol 28 (3) ◽

pp. 795-805 ◽

Cited By ~ 38

Author(s):

J. Liu ◽

B. Zhao ◽

L. Liu

Keyword(s):

Time Delay ◽

Local Time ◽

Positive Phase ◽

Negative Phase ◽

Electron Content ◽

Geomagnetic Disturbances ◽

Total Electron ◽

Low Latitudes ◽

Summer Hemisphere ◽

Winter Hemisphere

Abstract. Although positive and negative signatures of ionospheric storms have been reported many times, global characteristics such as the time of occurrence, time delay and duration as well as their relations to the intensity of the ionospheric storms have not received enough attention. The 10 years of global ionosphere maps (GIMs) of total electron content (TEC) retrieved at Jet Propulsion Laboratory (JPL) were used to conduct a statistical study of the time delay of the ionospheric responses to geomagnetic disturbances. Our results show that the time delays between geomagnetic disturbances and TEC responses depend on season, magnetic local time and magnetic latitude. In the summer hemisphere at mid- and high latitudes, the negative storm effects can propagate to the low latitudes at post-midnight to the morning sector with a time delay of 4–7 h. As the earth rotates to the sunlight, negative phase retreats to higher latitudes and starts to extend to the lower latitude toward midnight sector. In the winter hemisphere during the daytime and after sunset at mid- and low latitudes, the negative phase appearance time is delayed from 1–10 h depending on the local time, latitude and storm intensity compared to the same area in the summer hemisphere. The quick response of positive phase can be observed at the auroral area in the night-side of the winter hemisphere. At the low latitudes during the dawn-noon sector, the ionospheric negative phase responses quickly with time delays of 5–7 h in both equinoctial and solsticial months. Our results also manifest that there is a positive correlation between the intensity of geomagnetic disturbances and the time duration of both the positive phase and negative phase. The durations of both negative phase and positive phase have clear latitudinal, seasonal and magnetic local time (MLT) dependence. In the winter hemisphere, long durations for the positive phase are 8–11 h and 12–14 h during the daytime at middle and high latitudes for 20≤Ap<40 and Ap≥40.

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Case study on total electron content enhancements at low latitudes during low geomagnetic activities before the storms

Annales Geophysicae ◽

10.5194/angeo-26-893-2008 ◽

2008 ◽

Vol 26 (4) ◽

pp. 893-903 ◽

Cited By ~ 27

Author(s):

◽

Keyword(s):

Total Electron Content ◽

Geomagnetic Activity ◽

Electron Content ◽

Low Latitude ◽

Total Electron ◽

Defense Meteorological Satellite Program ◽

Low Latitudes ◽

Global Ionospheric Maps ◽

Geomagnetic Activities

Abstract. Sometimes the ionospheric total electron content (TEC) is significantly enhanced during low geomagnetic activities before storms. In this article, we investigate the characteristics of those interesting TEC enhancements using regional and global TEC data. We analyzed the low-latitude TEC enhancement events that occurred around longitude 120° E on 10 February 2004, 21 January 2004, and 4 March 2001, respectively. The TEC data are derived from regional Global Positioning System (GPS) observations in the Asia/Australia sector as well as global ionospheric maps (GIMs) produced by Jet Propulsion Laboratory (JPL). Strong enhancements under low geomagnetic activity before the storms are simultaneously presented at low latitudes in the Asia/Australia sector in regional TEC and JPL GIMs. These TEC enhancements are shown to be regional events with longitudinal and latitudinal extent. The regions of TEC enhancements during these events are confined at narrow longitude ranges around longitude 120° E. The latitudinal belts of maxima of enhancements locate around the northern and southern equatorial ionization anomaly (EIA) crests, which are consistent with those low-latitude events presented by Liu et al. (2008). During the 4 March 2001 event, the total plasma density Ni observed by the Defense Meteorological Satellite Program (DMSP) spacecraft F13 at 840 km altitude are of considerably higher values on 4 March than on the previous day in the TEC enhanced regions. Some TEC enhancement events are possibly due to contributions from auroral/magnetospheric origins; while there are also quasi-periodic enhancement events not related to geomagnetic activity and associated probably with planetary wave type oscillations (e.g. the 6 January 1998 event). Further investigation is warrented to identify/separate contributions from possible sources.

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