scholarly journals Seismogenic Disturbances of the Ionosphere During High Geomagnetic Activity

Atmosphere ◽  
2019 ◽  
Vol 10 (7) ◽  
pp. 359 ◽  
Author(s):  
Aleksandr Namgaladze ◽  
Mikhail Karpov ◽  
Maria Knyazeva
Keyword(s):  
Decisive Role ◽  
Electron Content ◽  
First Principle ◽  
Earthquake Epicenter ◽  
Geomagnetic Disturbances ◽  
Total Electron ◽  
Ionospheric Effects ◽  
Vertical Electric Field ◽  
Western Side ◽  
Seismic Origin

Herein, we analyze the variations in the ionosphere for the period of two weeks before the M6.7 earthquake in India on January 3, 2016. The earthquake occurred after a series of magnetic substorms on December 31, 2015 and January 1, 2016. The relative total electron content (TEC) disturbances have been estimated using global TEC maps and calculated numerically using the 3D global first-principle Upper Atmosphere Model (UAM) for the whole period including the days before, during, and after the substorms. Numerical simulations were repeated with the seismogenic vertical electric currents switched on at the earthquake epicenter. The UAM calculations have reproduced the general behavior of the ionosphere after the main phase of the geomagnetic storm on January 1, 2016 in the form of negative TEC disturbances propagating from high latitudes, being especially strong in the Southern (summer condition) Hemisphere. It was shown that the local ionospheric effects of seismic origin can be identified in the background of the global geomagnetic disturbances. The seismo-ionospheric effects are visible in the nighttime regions with the additional negative TEC disturbances extending from the eastern side of the epicenter meridian to the western side, both in the observations and in the UAM simulations. It was found that the vertical electric field and corresponding westward component of the electromagnetic [E × B] drift played a decisive role in the formation of the ionospheric precursors of this earthquake.

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

2010 ◽  
Vol 28 (3) ◽  
pp. 795-805 ◽  
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.

scholarly journals Modification of the low-latitude ionosphere before the 26 December 2004 Indonesian earthquake

2006 ◽  
Vol 6 (5) ◽  
pp. 817-823 ◽  
Author(s):  
I. E. Zakharenkova ◽  
A. Krankowski ◽  
I. I. Shagimuratov
Keyword(s):  
Electron Content ◽  
Equatorial Anomaly ◽  
Low Latitude ◽  
Total Electron ◽  
Ionospheric Effects ◽  
Earthquake Preparation ◽  
Low Latitude Ionosphere ◽  
Positive Effect ◽  
Possible Cause ◽  
Gps Observations

Abstract. This paper investigates the features of pre-earthquake ionospheric anomalies in the total electron content (TEC) data obtained on the basis of regular GPS observations from the IGS network. For the analysis of the ionospheric effects of the 26 December 2004 Indonesian earthquake, global TEC maps were used. The possible influence of the earthquake preparation processes on the main low-latitude ionosphere peculiarity – the equatorial anomaly – is discussed. Analysis of the TEC maps has shown that modification of the equatorial anomaly occurred a few days before the earthquake. For 2 days prior to the event, a positive effect was observed in the daytime amplification of the equatorial anomaly. Maximal enhancement in the crests reached 20 TECU (50–60%) relative to the non-disturbed state. In previous days, during the evening and night hours (local time), a specific transformation of the TEC distribution had taken place. This modification took the shape of a double-crest structure with a trough near the epicenter, though usually in this time the restored normal latitudinal distribution with a maximum near the magnetic equator is observed. It is assumed that anomalous electric field generated in the earthquake preparation zone could cause a near-natural "fountain-effect" phenomenon and might be a possible cause of the observed ionospheric anomaly.

scholarly journals Geomagnetic control of the spectrum of traveling ionospheric disturbances based on data from a global GPS network

2001 ◽  
Vol 19 (7) ◽  
pp. 723-731 ◽  
Author(s):  
E. L. Afraimovich ◽  
E. A. Kosogorov ◽  
O. S. Lesyuta ◽  
I. I. Ushakov ◽  
A. F. Yakovets
Keyword(s):  
Geomagnetic Activity ◽  
Time Derivative ◽  
Power Spectra ◽  
Small Scale ◽  
Electron Content ◽  
Ionospheric Disturbances ◽  
Geomagnetic Disturbances ◽  
Absolute Level ◽  
Total Electron ◽  
Traveling Ionospheric Disturbances

Abstract. In this paper an attempt is made to verify the hypothesis of the role of geomagnetic disturbances as a factor in determining the intensity of traveling ionospheric disturbances (TIDs). To improve the statistical validity of the data, we have used the method involving a global spatial averaging of disturbance spectra of the total electron content (TEC). To characterize the TID intensity quantitatively, we suggest that a new global index of the degree of disturbance should be used, which is equal to the mean value of the rms variations in TEC within the selected range of spectral periods (of 20– 60 min, in the present case). The analysis has been made for a set of 100 to 300 GPS stations for 10 days with a different level of geomagnetic activity (Dst from 0 to –350 nT; the Kp index from 3 to 9). It was found that power spectra of daytime TEC variations in the range of 20–60 min periods under quiet conditions have a power-law form with the slope index k = –2.5. With an increase in the level of magnetic disturbance, there is an increase in the total intensity of TIDs, with a concurrent kink of the spectrum caused by an increase in oscillation intensity in the range of 20–60 min. The TEC variation amplitude is found to be smaller at night than during the daytime, and the spectrum decreases in slope, which is indicative of a disproportionate increase in the amplitude of the small-scale part of the spectrum. It was found that an increase in the level of geomagnetic activity is accompanied by an increase in the total intensity of TEC; however, it does not correlate with the absolute level of Dst, but rather with the value of the time derivative of Dst (a maximum correlation coefficient reaches –0.94). The delay of the TID response of the order of 2 hours is consistent with the view that TIDs are generated in auroral regions, and propagate equatorward with the velocity of about 300–400 m/s.Key words. Ionosphere (ionospheric disturbances; auroral ionosphere; equatorial ionopshere)

scholarly journals Comparison of simultaneous variations of the ionospheric total electron content and geomagnetic field associated with strong earthquakes

2001 ◽  
Vol 1 (1/2) ◽  
pp. 53-59 ◽  
Author(s):  
Sh. Naaman ◽  
L. S. Alperovich ◽  
Sh. Wdowinski ◽  
M. Hayakawa ◽  
E. Calais
Keyword(s):  
Total Electron Content ◽  
Vertical Displacement ◽  
Temporal Variations ◽  
Electron Content ◽  
Geomagnetic Disturbances ◽  
Total Electron ◽  
Strong Earthquakes ◽  
Ionospheric Total Electron Content ◽  
Geomagnetic Observations ◽  
Gps Observations

Abstract. In this paper, perturbations of the ionospheric Total Electron Content (TEC) are compared with geomagnetic oscillations. Comparison is made for a few selected periods, some during earthquakes in California and Japan and others at quiet periods in Israel and California. Anomalies in TEC were extracted using Global Positioning System (GPS) observations collected by GIL (GPS in Israel) and the California permanent GPS networks. Geomagnetic data were collected in some regions where geomagnetic observatories and the GPS network overlaps. Sensitivity of the GPS method and basic wave characteristics of the ionospheric TEC perturbations are discussed. We study temporal variations of ionospheric TEC structures with highest reasonable spatial resolution around 50 km. Our results show no detectable TEC disturbances caused by right-lateral strike-slip earthquakes with minor vertical displacement. However, geomagnetic observations obtained at two observatories located in the epicenter zone of a strong dip-slip earthquake (Kyuchu, M = 6.2, 26 March 1997) revealed geomagnetic disturbances occurred 6–7 h before the earthquake.

scholarly journals Morphology in the total electron content under geomagnetic disturbed conditions: results from global ionosphere maps

2007 ◽  
Vol 25 (7) ◽  
pp. 1555-1568 ◽  
Author(s):  
Zhao Biqiang ◽  
Wan Weixing ◽  
Liu Libo ◽  
Mao Tian
Keyword(s):  
Geomagnetic Storm ◽  
Local Time ◽  
Statistical Study ◽  
Electron Content ◽  
Geomagnetic Disturbances ◽  
Total Electron ◽  
Summer Hemisphere ◽  
Storm Effect ◽  
Time Variations ◽  
Winter Hemisphere

Abstract. Using 8-year global ionosphere maps (GIMs) of TEC products from the Jet Propulsion Laboratory (JPL), we make a statistical study on the morphology of the global ionospheric behaviors with respect to the geomagnetic disturbances. Results show that the behaviors of TEC during geomagnetic storm present clear seasonal and local time variations under geomagnetic control in a similar way as those of NmF2 (Field and Rishbeth, 1997). A negative phase of TEC occurs with high probability in the summer hemisphere and most prominent near the geomagnetic poles, while a positive phase is obvious in the winter hemisphere and in the far pole region. A negative storm effect toward lower latitudes tends to occur from post-midnight to the morning sector and recedes to high latitude in the afternoon. A positive storm effect is separated by geomagnetic latitudes and magnetic local time. Furthermore, ionospheric responses at different local time sectors with respect to the storm commencement shows very different developing processes corresponding to the evolution of the geomagnetic storm. A daytime positive storm effect is shown to be more prominent in the American region than those in the Asian and European regions, which may suggest a longitudinal effect of the ionospheric storm.

scholarly journals Understanding the ionosphere thermosphere response to solar and magnetospheric drivers: status, challenges and open issues

2019 ◽  
Vol 377 (2148) ◽  
pp. 20180101 ◽  
Author(s):  
Theodore E. Sarris
Keyword(s):  
Electric Fields ◽  
Spatial Scales ◽  
Modern Technology ◽  
External Factors ◽  
Ionospheric Scintillation ◽  
Electron Content ◽  
Geomagnetically Induced Currents ◽  
Geomagnetic Disturbances ◽  
Total Electron ◽  
Open Issues

The ionosphere and thermosphere (IT) constitutes a coupled, complex and dynamical electromagnetic and photochemical system, which is sensitive to a combination of external factors: particle precipitation and electrical currents from the Earth's magnetosphere and incoming solar radiation produce dramatic effects in the IT and significantly alter its energetics, dynamics and chemistry in a way that is not well understood. This sensitivity of the IT to external factors results in large, yet often unpredictable changes in many of the variables in the IT, such as in its density, temperature, neutral and ion winds, total electron content, neutral and ion composition, electric fields, currents and conductivities. External forcing of the IT system varies over different time-scales, such as solar cycle (11-year), inter-annual (e.g. quasi-biennial), seasonal and diurnal; on top of these, geomagnetic disturbances caused by solar storms and substorms can lead to abrupt reconfigurations of the magnetospheric field-aligned and horizontal currents, setting a number of electrodynamics processes in motion. The overlapping physical and chemical phenomena occur at a range of temporal and spatial scales that are highly difficult to understand as a whole. The importance of the behaviour of this region to multiple issues related to aerospace technology, such as orbital calculations, vehicle re-entry, space debris lifetime, etc., and its potential threats to modern, technology-dependent society via geomagnetically induced currents and ionospheric scintillation of Global Navigation Satellite System signals, dictate that a more detailed understanding and accurate modelling are urgently needed. In this paper, we review the status of characterization and some of the key open issues and challenges of the IT, focusing on measurement gaps in this region as well as areas of largest discrepancies between models and data.This article is part of the theme issue ‘Solar eruptions and their space weather impact’.

scholarly journals A first-principle derivation of the high-latitude total electron content distribution

Radio Science ◽  
1993 ◽  
Vol 28 (1) ◽  
pp. 49-61 ◽  
Author(s):  
D. J. Crain ◽  
J. J. Sojka ◽  
R. W. Schunk ◽  
P. H. Doherty ◽  
J. A. Klobuchar
Keyword(s):  
Total Electron Content ◽  
High Latitude ◽  
Content Distribution ◽  
Electron Content ◽  
First Principle ◽  
Total Electron

scholarly journals Ionospheric reaction on sudden stratospheric warming events in Russia´s Asia region

2015 ◽  
Vol 1 (4) ◽  
pp. 47-57 ◽  
Author(s):  
Анна Полякова ◽  
Anna Polyakova ◽  
Марина Черниговская ◽  
Marina Chernigovskaya ◽  
Наталья Перевалова ◽  
...  
Keyword(s):  
Solar Maximum ◽  
Background Level ◽  
Reanalysis Data ◽  
Joint Analysis ◽  
Electron Content ◽  
Sudden Stratospheric Warming ◽  
Total Electron ◽  
Ionospheric Effects ◽  
Global Ionospheric Maps ◽  
First Time

The response of the ionosphere to sudden stratospheric warmings (SSWs) in the Asian region of Russia is studied. Two SSW events observed in 2008–2009 and 2012–2013 winter periods of extreme solar minimum and moderate solar maximum are considered. To detect the ionospheric effects caused by SSWs, we carried out a joint analysis of global ionospheric maps (GIM) of the total electron content (TEC), MLS (Microwave Limb Sounder, EOS Aura) measurements of temperature vertical profiles, as well as NCEP/NCAR and UKMO Reanalysis data. For the first time, it was found that during strong SSWs, in the mid-latitude ionosphere the amplitude of diurnal TEC variation decreases nearly half compared to quiet days. At the same time, the intensity of TEC deviations from the background level increases. It was also found that at SSW peak the midday TEC maximum decreases, and night/morning TEC values increase compared to quiet days. It was shown that during SSWs, TEC dynamics was identical for different geophysical conditions.

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