scholarly journals A total electron content space weather study of the nighttime Weddell Sea Anomaly of 1996/1997 southern summer with TOPEX/Poseidon radar altimetry

2006 ◽  
Vol 111 (A12) ◽  
Author(s):  
Ildiko Horvath
Keyword(s):  
Total Electron Content ◽  
Space Weather ◽  
Weddell Sea ◽  
Electron Content ◽  
Radar Altimetry ◽  
Total Electron ◽  
Weddell Sea Anomaly

scholarly journals Ionospheric Response to the Space Weather Events of 4-10 September 2017: First Chilean Observations

2019 ◽  
Vol 13 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Manuel Bravo ◽  
Carlos Villalobos ◽  
Rodrigo Leiva ◽  
Luis Tamblay ◽  
Pedro Vega-Jorquera ◽  
...  
Keyword(s):  
Total Electron Content ◽  
Space Weather ◽  
Global Navigation Satellite Systems ◽  
Time Interval ◽  
Electron Content ◽  
Dual Frequency ◽  
Field Station ◽  
Total Electron ◽  
Satellite Systems ◽  
Weather Events

Objective: The diurnal variations of several ionospheric characteristics during the Space Weather Events of 4-10 September 2017, for Chilean latitudes, will be reported. Materials and Methods: Observations were made using a recently installed ionosonde at the Universidad de La Serena field station (29°52'S; 71°15’W). Also, reported is the total electron content determined using the upgraded Chilean network of dual-frequency Global Navigation Satellite Systems (GNSS) receivers. Results: Sudden ionospheric disturbances are described in terms of the minimum reflection frequency determined from ionosonde records. An attempt to derive the extent of the effect on high frequency propagation paths in the region is made using simultaneous ionosonde observations at other locations. The geomagnetic storm ionospheric effects are discussed in detail using the observed diurnal variation of maximum electron concentration (NmF2), virtual height of the F-region (h’F/F2) and Total Electron Content (TEC). These are complemented with the time-latitude variation of TEC for the 70°W meridian. Conclusion: It is found that large increases of NmF2, h’F/F2 and TEC observed during 8 September 2017 storm are well described in terms of the evolution of the Equatorial Ionospheric Anomaly (EIA) over the same time interval. Known physical mechanisms are suggested to explain most of the observations.

scholarly journals INVESTIGATION OF THE RELATIONSHIP BETWEEN IONOSPHERIC TEC ANOMALY VARIATIONS AND FAULT TYPES BEFORE THE EARTHQUAKES

2017 ◽  
Vol IV-4/W4 ◽  
pp. 383-388 ◽  
Author(s):  
M. Ulukavak ◽  
M. Yalçınkaya
Keyword(s):  
Total Electron Content ◽  
Space Weather ◽  
Environmental Changes ◽  
Weather Conditions ◽  
Earthquake Precursor ◽  
Strike Slip ◽  
Time Of Arrival ◽  
Electron Content ◽  
Total Electron ◽  
Fault Type

Earthquakes are natural phenomena that shake the earth and cause many damage. Since the time of arrival of the earthquakes cannot be determined directly, some signs before the earthquake should be examined and interpreted by examining the environmental changes. One of the methods used for this is monitoring the ionospheric total electron content (TEC) changes in total electron content unit (TECU). GPS satellites have begun to be used as a means of monitoring ionospheric TEC anomalies before earthquakes since they began to be used as sensors around the world. In this study, three fault type (normal, thrust and strike-slip faulting) of 28 earthquakes with a magnitude greater than 7 (Mw) and the percentage changes of TEC anomalies before the earthquakes were investigated. The ionospheric TEC anomalies before the earthquake were calculated according to the 15-day running median statistical analysis method. Different solar and geomagnetic indices have been investigated to determine the active space weather conditions and quiet days before and after the earthquake. The TEC anomalies were determined during the quiet days before the earthquake by comparing the ionospheric anomalies that occurred before the earthquake after the determination of quiet days with the indices of the space weather conditions. The results show that there is a relationship between fault type and the earthquake precursor percentage changes and were determined as 47.6 % TECU for regions where normal faulting, 50.4 % TECU for regions where thrust faulting, and 44.2 % TECU for regions where strike-slip faulting occurred, respectively.

Observations of ionospheric TEC peaked structures from Global Ionosphere Maps

2020 ◽  
Author(s):  
Tsung-Che Tsai ◽  
Hau-Kun Jhuang ◽  
Lou-Chuang Lee ◽  
Yi-Ying Ho
Keyword(s):  
Local Time ◽  
Geomagnetic Latitude ◽  
Weddell Sea ◽  
Electron Content ◽  
Destructive Interference ◽  
Total Electron ◽  
Weddell Sea Anomaly ◽  
Time Structures ◽  
Time Frames ◽  
Wave Modes

<p>The total electron content (TEC) data from Global Ionosphere Maps provide a global TEC map in the region between latitude 87.5°S to 87.5°N, and longitude 180°W to 180°E. The TEC data in geographic coordinates are first transformed into geomagnetic coordinates through Altitude-Adjusted Corrected Geomagnetic Model (AACGM). We then use 2-dimensional (longitudinal, 180°W-180°E and time, 10 days) Fourier transform (FT) of TEC variations along different geomagnetic latitude to obtain all wave modes in both UT (universal time) and LT (local time) frames for the period from November 18, 2002 to October 15, 2014. The summation of contributing wave modes at a given local time provides the longitudinal variation of the associated zonal waves. The phases of wave modes lead to a constructive or destructive interference of contributing zonal wave, which gives different structures at different local time. These local time structures include Weddell Sea Anomaly (WSA), Southern Atlantic Anomaly (SAA), and Four-peaked structure. The dependence of the peaked structures on latitudinal, seasonal, and solar activity is studied.</p>

The hemispheric asymmetry of ionospheric lunitidal signatures during Sudden Stratospheric Warmings in the eastern Asian and American sectors

2021 ◽  
Author(s):  
Jing Liu ◽  
Donghe Zhang ◽  
Larisa Goncharenko ◽  
Shun-Rong Zhang ◽  
Maosheng He ◽  
...  
Keyword(s):  
Hemispheric Asymmetry ◽  
Field Configuration ◽  
Weddell Sea ◽  
Electron Content ◽  
Total Electron ◽  
Total Electron Content Data ◽  
Vertical Coupling ◽  
F Region ◽  
Weddell Sea Anomaly ◽  
Plasma Distribution

<p>During Sudden Stratospheric Warming events, the ionosphere exhibits phase-shifted semi-diurnal perturbations, which are typically attributed to vertical coupling associated with the semi-diurnal lunar tide (M2). Our understanding of ionospheric responses to M2 is limited. This study focuses on fundamental vertical coupling processes associated with the latitudinal extent and hemispheric asymmetry of ionospheric M2 signatures, using total electron content data from the eastern Asian and American sectors. Our results illustrate that the asymmetry maximizes at around 15°N and 20°S magnetic latitudes. In the southern hemisphere, the M2-like signatures extend deep into midlatitude and, in the American sector, encounter the Weddell Sea Anomaly. The M2 amplitude is larger in the northern hemisphere and such asymmetry is more distinct in the eastern Asian sector. The hemispheric asymmetry of M2 signatures in the low latitude can be primarily explained by the trans-equatorial wind modulation of the equatorial plasma fountain. Other physical processes could also be relevant, including hemispheric asymmetry of the M2 below the F region, the ambient thermospheric composition and ionospheric plasma distribution, and the geomagnetic field configuration.</p>

scholarly journals GPS normalization and preliminary modeling results of total electron content during a midlatitude space weather event

Radio Science ◽  
2001 ◽  
Vol 36 (2) ◽  
pp. 351-361 ◽  
Author(s):  
Jonathan J. Makela ◽  
Michael C. Kelley ◽  
Jan J. Sojka ◽  
Xiaoqing Pi ◽  
Anthony J. Mannucci
Keyword(s):  
Total Electron Content ◽  
Space Weather ◽  
Electron Content ◽  
Weather Event ◽  
Total Electron ◽  
Space Weather Event

scholarly journals Spatial and Temporal Variations of Polar Ionospheric Total Electron Content over Nearly Thirteen Years

Sensors ◽  
2020 ◽  
Vol 20 (2) ◽  
pp. 540 ◽  
Author(s):  
Hui Xi ◽  
Hu Jiang ◽  
Jiachun An ◽  
Zemin Wang ◽  
Xueyong Xu ◽  
...  
Keyword(s):  
Solar Activity ◽  
Total Electron Content ◽  
Geomagnetic Storms ◽  
Weddell Sea ◽  
The Arctic ◽  
Electron Content ◽  
Spherical Cap ◽  
Total Electron ◽  
Ionospheric Total Electron Content ◽  
The Antarctic

It is of great significance for the global navigation satellite system (GNSS) service to detect the polar ionospheric total electron content (TEC) and its variations, particularly under disturbed ionosphere conditions, including different phases of solar activity, the polar day and night alternation, the Weddell Sea anomaly (WSA) as well as geomagnetic storms. In this paper, four different models are utilized to map the ionospheric TEC over the Arctic and Antarctic for about one solar cycle: the polynomial (POLY) model, the generalized trigonometric series function (GTSF) model, the spherical harmonic (SH) model, and the spherical cap harmonic (SCH) model. Compared to other models, the SCH model has the best performance with ±0.8 TECU of residual mean value and 1.5–3.5 TECU of root mean square error. The spatiotemporal distributions and variations of the polar ionospheric TEC are investigated and compared under different ionosphere conditions in the Arctic and Antarctic. The results show that the solar activity significantly affects the TEC variations. During polar days, the ionospheric TEC is more active than it is during polar nights. In polar days over the Antarctic, the maximum value of TEC always appears at night in the Antarctic Peninsula and Weddell Sea area affected by the WSA. In the same year, the ionospheric TEC of the Antarctic has a larger amplitude of annual variation than that of the TEC in the Arctic. In addition, the evolution of the ionization patch during a geomagnetic storm over the Antarctic can be clearly tracked employing the SCH model, which appears to be adequate for mapping the polar TEC, and provides a sound basis for further automatic identification of ionization patches.

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