Morphology of high‐latitude plasma density perturbations as deduced from the total electron content measurements onboard the Swarm constellation

Abstract. In this paper, we report significant evidence for preseismic ionospheric anomalies in total electron content (TEC) of the global ionosphere map (GIM) and plasma density appearing on day 2 before the 17 July 2006 M7.7 south of Java earthquake. After distinguishing other anomalies related to the geomagnetic activities, we found a temporal precursor around the epicenter on day 2 before the earthquake (15 July 2006), which agrees well with the spatial variations in latitude–longitude–time (LLT) maps. Meanwhile, the sequences of latitude–time–TEC (LTT) plots reveal that the TECs on epicenter side anomalously decrease and lead to an anomalous asymmetric structure with respect to the magnetic equator in the daytime from day 2 before the earthquake. This anomalous asymmetric structure disappears after the earthquake. To further confirm these anomalies, we studied the plasma data from DEMETER satellite in the earthquake preparation zone (2046.4 km in radius) during the period from day 45 before to day 10 after the earthquake, and also found that the densities of both electron and total ion in the daytime significantly increase on day 2 before the earthquake. Very interestingly, O+ density increases significantly and H+ density decreases, while He+ remains relatively stable. These results indicate that there exists a distinct preseismic signal (preseismic ionospheric anomaly) over the epicenter.

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

Radio Science ◽

10.1029/92rs01928 ◽

1993 ◽

Vol 28 (1) ◽

pp. 49-61 ◽

Cited By ~ 3

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

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GPS scintillations and total electron content climatology in the southern low, middle and high latitude regions

Annals of Geophysics ◽

10.4401/ag-6240 ◽

2013 ◽

Vol 56 (2) ◽

Author(s):

Luca Spogli ◽

Lucilla Alfonsi ◽

Pierre J. Cilliers ◽

Emília Correia ◽

Giorgiana De Franceschi ◽

...

Keyword(s):

Total Electron Content ◽

High Latitude ◽

Current Knowledge ◽

Hot Spot ◽

Ionospheric Scintillation ◽

Electron Content ◽

Total Electron ◽

Plasma Irregularities ◽

Gps Scintillations ◽

High Frequency Sampling

<p>In recent years, several groups have installed high-frequency sampling receivers in the southern middle and high latitude regions, to monitor ionospheric scintillations and the total electron content (TEC) changes. Taking advantage of the archive of continuous and systematic observations of the ionosphere on L-band by means of signals from the Global Positioning System (GPS), we present the first attempt at ionospheric scintillation and TEC mapping from Latin America to Antarctica. The climatology of the area considered is derived through Ground-Based Scintillation Climatology, a method that can identify ionospheric sectors in which scintillations are more likely to occur. This study also introduces the novel ionospheric scintillation 'hot-spot' analysis. This analysis first identifies the crucial areas of the ionosphere in terms of enhanced probability of scintillation occurrence, and then it studies the seasonal variation of the main scintillation and TEC-related parameters. The results produced by this sophisticated analysis give significant indications of the spatial/ temporal recurrences of plasma irregularities, which contributes to the extending of current knowledge of the mechanisms that cause scintillations, and consequently to the development of efficient tools to forecast space-weather-related ionospheric events.</p>

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Response of High Latitude Ionospheric TEC to Enhanced Radiation Fluxes during the Major Solar Flare Events

Journal of Scientific Research ◽

10.3329/jsr.v6i1.14100 ◽

2013 ◽

Vol 6 (1) ◽

pp. 43-49 ◽

Cited By ~ 1

Author(s):

P. K. Purohit ◽

A. A. Mansoori ◽

P. A. Khan ◽

P. Bhawre ◽

S. C. Tripathi ◽

...

Keyword(s):

Solar Flare ◽

Total Electron Content ◽

High Latitude ◽

Solar Disc ◽

Electron Content ◽

Central Meridian ◽

Total Electron ◽

X Ray ◽

Radiation Fluxes ◽

Peak Enhancement

We have investigated the response of ionosphere to major solar flare events that occurred during 1998 to 2011. The effect of enhanced radiation fluxes in the X-ray and EUV band on the GPS derived Total Electron Content (TEC) is examined. The data of X-ray flux from Geostationary Operational Environment Satellite (GOES) and EUV flux from Solar EUV Monitor (SEM) onboard SOHO spacecraft were correlated with the Total Electron Content (TEC) data of a high latitude station, Davis (68.570S, 77.960E). We found that peak intensities of X-ray and EUV flux correlate very well with the peak values of TEC. We also studied the correlation of peak enhancement of these fluxes with the peak enhancement of TEC and found that peak enhancement of these fluxes correlate highly with the peak enhancement of TEC than with the peak values themselves. It is also found that correlation is extraordinarily improved when these fluxes are multiplied by Cos(CMD) where CMD is Central Meridian Distance on the solar disc, thereby showing that the location of flares on the solar disc plays an important role while investigating the ionospheric influences of solar flares. Keywords: Ionosphere; TEC; CMD; Solar Flare. © 2014 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved. doi: http://dx.doi.org/10.3329/jsr.v6i1.14100 J. Sci. Res. 6 (1), 43-49 (2014)

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