Lunar Tidal Effect on Equatorial Ionization Anomaly Region in China Low Latitude

2021 ◽  
Author(s):  
Xiaohua Mo ◽  
Donghe Zhang ◽  
Jing Liu ◽  
Yongqiang Hao ◽  
Zuo Xiao ◽  
...  
Keyword(s):  
Tidal Effect ◽  
Low Latitude ◽  
Equatorial Ionization Anomaly ◽  
Anomaly Region

scholarly journals High-speed stream impacts on the equatorial ionization anomaly region during the deep solar minimum year 2008

2012 ◽  
Vol 117 (A10) ◽  
pp. n/a-n/a ◽  
Author(s):  
Jing Liu ◽  
Libo Liu ◽  
Biqiang Zhao ◽  
Yong Wei ◽  
Lianhuan Hu ◽  
...  
Keyword(s):  
Solar Minimum ◽  
High Speed ◽  
High Speed Stream ◽  
Equatorial Ionization Anomaly ◽  
Anomaly Region

scholarly journals An investigation of the ionospheric F region near the EIA crest in India using OI 777.4 and 630.0 nm nightglow observations

2018 ◽  
Vol 36 (3) ◽  
pp. 809-823 ◽  
Author(s):  
Navin Parihar ◽  
Sandro Maria Radicella ◽  
Bruno Nava ◽  
Yenca Olivia Migoya-Orue ◽  
Prabhakar Tiwari ◽  
...  
Keyword(s):  
Electron Density ◽  
Gravity Waves ◽  
Satellite Mission ◽  
Low Latitude ◽  
Density Maximum ◽  
Density Profiles ◽  
F Region ◽  
Equatorial Ionization Anomaly ◽  
Low Latitude Ionosphere ◽  
Electron Density Profiles

Abstract. Simultaneous observations of OI 777.4 and OI 630.0 nm nightglow emissions were carried at a low-latitude station, Allahabad (25.5° N, 81.9° E; geomag. lat.  ∼  16.30° N), located near the crest of the Appleton anomaly in India during September–December 2009. This report attempts to study the F region of ionosphere using airglow-derived parameters. Using an empirical approach put forward by Makela et al. (2001), firstly, we propose a novel technique to calibrate OI 777.4 and 630.0 nm emission intensities using Constellation Observing System for Meteorology, Ionosphere, and Climate/Formosa Satellite Mission 3 (COSMIC/FORMOSAT-3) electron density profiles. Next, the electron density maximum (Nm) and its height (hmF2) of the F layer have been derived from the information of two calibrated intensities. Nocturnal variation of Nm showed the signatures of the retreat of the equatorial ionization anomaly (EIA) and the midnight temperature maximum (MTM) phenomenon that are usually observed in the equatorial and low-latitude ionosphere. Signatures of gravity waves with time periods in the range of 0.7–3.0 h were also seen in Nm and hmF2 variations. Sample Nm and hmF2 maps have also been generated to show the usefulness of this technique in studying ionospheric processes.

scholarly journals The transient variation in the complexes of the low-latitude ionosphere within the equatorial ionization anomaly region of Nigeria

2015 ◽  
Vol 22 (5) ◽  
pp. 527-543 ◽  
Author(s):  
A. B. Rabiu ◽  
B. O. Ogunsua ◽  
I. A. Fuwape ◽  
J. A. Laoye
Keyword(s):  
Time Series ◽  
Lyapunov Exponent ◽  
Lyapunov Exponents ◽  
Correlation Dimension ◽  
Tsallis Entropy ◽  
Variation Pattern ◽  
Dynamical Complexity ◽  
Equatorial Ionization Anomaly ◽  
Non Linear ◽  
Anomaly Region

Abstract. The quest to find an index for proper characterization and description of the dynamical response of the ionosphere to external influences and its various internal irregularities has led to the study of the day-to-day variations of the chaoticity and dynamical complexity of the ionosphere. This study was conducted using Global Positioning System (GPS) total electron content (TEC) time series, measured in the year 2011, from five GPS receiver stations in Nigeria, which lies within the equatorial ionization anomaly region. The non-linear aspects of the TEC time series were obtained by detrending the data. The detrended TEC time series were subjected to various analyses to obtain the phase space reconstruction and to compute the chaotic quantifiers, which are Lyapunov exponents LE, correlation dimension, and Tsallis entropy, for the study of dynamical complexity. Considering all the days of the year, the daily/transient variations show no definite pattern for each month, but day-to-day values of Lyapunov exponents for the entire year show a wavelike semiannual variation pattern with lower values around March, April, September and October. This can be seen from the correlation dimension with values between 2.7 and 3.2, with lower values occurring mostly during storm periods, demonstrating a phase transition from higher dimension during the quiet periods to lower dimension during storms for most of the stations. The values of Tsallis entropy show a similar variation pattern to that of the Lyapunov exponent, with both quantifiers correlating within the range of 0.79 to 0.82. These results show that both quantifiers can be further used together as indices in the study of the variations of the dynamical complexity of the ionosphere. The presence of chaos and high variations in the dynamical complexity, even in quiet periods in the ionosphere, may be due to the internal dynamics and inherent irregularities of the ionosphere which exhibit non-linear properties. However, this inherent dynamics may be complicated by external factors like geomagnetic storms. This may be the main reason for the drop in the values of the Lyapunov exponent and Tsallis entropy during storms. The dynamical behaviour of the ionosphere throughout the year, as described by these quantifiers, was discussed in this work.

scholarly journals Quiet Time Ionopheric Irregularities Over the African Equatorial Ionization Anomaly Region

Radio Science ◽  
2020 ◽  
Vol 55 (8) ◽  
Author(s):  
Paul O. Amaechi ◽  
Elijah O. Oyeyemi ◽  
Andrew O. Akala ◽  
Elijah O. Falayi ◽  
Mohamed Kaab ◽  
...  
Keyword(s):  
Quiet Time ◽  
Equatorial Ionization Anomaly ◽  
Anomaly Region

scholarly journals Magnetic storm-induced enhancement in neutral composition at low latitudes as inferred by O(<sup>1</sup>D) dayglow measurements from Chile

2004 ◽  
Vol 22 (9) ◽  
pp. 3241-3250 ◽  
Author(s):  
D. Pallamraju ◽  
S. Chakrabarti ◽  
C. E. Valladares
Keyword(s):  
Gravity Wave ◽  
Magnetic Storm ◽  
Geomagnetic Storm ◽  
Local Time ◽  
Direct Effect ◽  
Spatial Structures ◽  
Low Latitude ◽  
Equatorial Ionization Anomaly ◽  
Low Latitudes ◽  
Spread F

Abstract. We describe the effect of the 6 November 2001 magnetic storm on the low latitude thermospheric composition. Daytime red line (OI 630.0nm) emissions from Carmen Alto, Chile showed anomalous 2-3 times larger emissions in the morning (05:30-08:30 Local Time; LT) on the disturbed day compared to the quiet days. We interpret these emission enhancements to be caused due to the increase in neutral densities over low latitudes, as a direct effect of the geomagnetic storm. As an aftereffect of the geomagnetic storm, the dayglow emissions on the following day show gravity wave features that gradually increase in periodicities from around 30min in the morning to around 100min by the evening. The integrated dayglow emissions on quiet days show day-to-day variabilities in spatial structures in terms of their movement away from the magnetic equator in response to the Equatorial Ionization Anomaly (EIA) development in the daytime. The EIA signatures in the daytime OI 630.0nm column-integrated dayglow emission brightness show different behavior on days with and without the post-sunset Equatorial Spread F (ESF) occurrence.

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

2014 ◽  
Vol 32 (2) ◽  
pp. 121-131 ◽  
Author(s):  
X. H. Mo ◽  
D. H. Zhang ◽  
L. P. Goncharenko ◽  
Y. Q. Hao ◽  
Z. Xiao
Keyword(s):  
Large Scale ◽  
Maximum Amplitude ◽  
Equatorial Electrojet ◽  
Peak Height ◽  
Periodic Component ◽  
Low Latitude ◽  
Latitude Belt ◽  
Equatorial Ionization Anomaly ◽  
Periodic Movement ◽  
Atmospheric Variations

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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