The Southern Hemisphere and equatorial region ionization response for a 22 September 1999 severe magnetic storm

Yizengaw, E.; Essex, E. A.; Birsa, R.

doi:10.5194/angeo-22-2765-2004

Cited by 43 publications

(40 citation statements)

References 20 publications

(36 reference statements)

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“…The long TEC depression and positively high response of TEC during the storm at Scott Base station was in agreement with Yizengaw et al (2004) Note that, the scintillation event exhibited more pronounced activity during the recovery phase than that to the sudden storm commencement. This trend was also observed by Birsa et al (2002) at Vanimo (2.4°S, 141.4°E) and Shilo et al (1998) at Casey Station (66.28°S, 110.24°E).…”

Section: Discussionsupporting

confidence: 83%

GPS Ionospheric Total Electron Content and Scintillation Measurements during the October 2003 Magnetic Storm

Momani¹

2011

American Journal of Engineering and Applied Sciences

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Problem Statement: Ionospheric scintillations, cause significant effects on satellite signals for communication and navigation in equatorial region and polar regions mainly during sever magnetic storms periods. This phenomenon is not fully understood due to few studies performed. The study investigates variability of Total Electron Content (TEC) and ionospheric scintillation during October 2003 magnetic storm over Antarctica using ground based GPS technique. Approach: The TEC/scintillation measuring system at Scott Base station, consists of Trimble TS5700 24-channel (a high-precision dual-frequency GPS receiver), a Trimble Zephyr Geodetic antenna and a notebook computer for data logging. The absolute GPS TEC was calculated from differential phase advance GPS observables (1-L2). The GPS signal-to-noise ratios (C/No) and 1/L2 carrier frequencies were employed to determine the scintillation index S 4 every 60 s, amplitude scintillation (in dB-Hz) and phase scintillation. Results: The GPS measurements during storm periods at Scott Base show pronounced phase and amplitude scintillation activities, sudden increase in TEC followed by trough-like figure depletions. The maximum value of phase scintillation during the main phase of third episode was 8.3 times the value during Sudden Storm Commencement (SSC) period. Measured amplitude scintillation and S4 index on both 1 and L2 signals are >15dB-Hz and >0.4dB-Hz respectively. Conclusion/Recommendation: The timing and intensity of TEC and scintillation measurements during the storm event were are in a good agreement with WDC measurements. For this particular event, the duration of enhanced periods were approximately 12 h while periods of TEC depletions were more than 30 h. This value implies better understanding of the polar ionospheric response to magnetic storm and eases efforts for better space weather prediction in this region.

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Section: Discussionsupporting

confidence: 83%

GPS Ionospheric Total Electron Content and Scintillation Measurements during the October 2003 Magnetic Storm

Momani¹

2011

American Journal of Engineering and Applied Sciences

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“…Such a rapid expansion may cause upwelling, which induces a dramatic depletion of the atomic to molecular neutral density ratio. This change in chemical composition causes increased recombination in the ionosphere and a reduction in ionization concentration (Yizengaw et al, 2004). The positive phases are generally believed to be caused by uplifting of the F-region by equatorward winds in the early stage of a storm development.…”

Section: Discussionmentioning

confidence: 99%

Ionospheric temporal and spatial variations during the 18 August 2003 storm over China

Wen

Yuan

et al. 2007

Earth Planet Sp

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The effects of the 18 August 2003 geomagnetic storm on the ionosphere over China have been first studied by combining dual-frequency Global Positioning System (GPS) observation data from the Crustal Movement Observation Network of China (CMONOC) using the computerized ionospheric tomography (CIT) technique. The temporal and spatial variations of the ionosphere are analyzed using a time series of ionospheric electron density (IED) maps, and the ionospheric storm evolution process is revealed. The tomographic results show that the main ionospheric effects of this storm over China are: (1) that positive storm phase effects usually happen in the low-latitude ionosphere, (2) that negative storm phase effects occur in the mid-latitude ionosphere, and (3) that the equatorial anomaly structure can also be found. In contrast to the quiet period of the ionosphere on 17 August 2003, the equatorial anomaly crest moved to the north in the main phase of the storm and then moved back to the original location in the recovery phase on 19 August 2003. We compared the peak density N m F 2 and the peak height h m F 2 obtained from the ionosonde observations at Wuhan station and those inverted by the CIT technique to confirm the reliability of the GPS-based tomographic technique. The tomographic results revealed that the GPS-based CIT technique can be used to monitor large-scale ionospheric disturbances during geomagnetic storms.

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“…The magnitude and direction of E 9 B drift can be easily estimated using the ground-based magnetometer array (Anderson et al 2000). This is possible since the horizontal component of the geomagnetic field at the magnetic dip-equator reflects the change in the equatorial plasma fountain, and the difference between H at the equator and at a nonequatorial location is a good indicator of the vertical E 9 B drift (Anderson et al 2000;Yizengaw et al 2004Yizengaw et al , 2005a. In the ionospheric dynamo, the H-component reflects the EEJ current (Anderson et al 2000;Yizengaw et al 2004Yizengaw et al , 2005a.…”

Section: Description Of Techniques and Technical Backgroundmentioning

confidence: 99%

“…This is possible since the horizontal component of the geomagnetic field at the magnetic dip-equator reflects the change in the equatorial plasma fountain, and the difference between H at the equator and at a nonequatorial location is a good indicator of the vertical E 9 B drift (Anderson et al 2000;Yizengaw et al 2004Yizengaw et al , 2005a. In the ionospheric dynamo, the H-component reflects the EEJ current (Anderson et al 2000;Yizengaw et al 2004Yizengaw et al , 2005a. Therefore, using the magnetometer data from MAGDAS (Yumoto 2006) and the AMBER array and by applying the technique described in (Anderson et al 2000;Yizengaw et al 2004Yizengaw et al , 2005a we will continuously estimate the E 9 B drift.…”

Section: Description Of Techniques and Technical Backgroundmentioning

confidence: 99%

“…In the ionospheric dynamo, the H-component reflects the EEJ current (Anderson et al 2000;Yizengaw et al 2004Yizengaw et al , 2005a. Therefore, using the magnetometer data from MAGDAS (Yumoto 2006) and the AMBER array and by applying the technique described in (Anderson et al 2000;Yizengaw et al 2004Yizengaw et al , 2005a we will continuously estimate the E 9 B drift. This can be possible by differencing H-component field recorded at a non-equator magnetometer (H non-equator ) from the H-component value measured by a magnetometer at the magnetic equator (H equator ).…”

Section: Description Of Techniques and Technical Backgroundmentioning

confidence: 99%

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African Meridian B-Field Education and Research (AMBER) Array

Yizengaw

Moldwin

2009

Earth Moon Planet

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The AMBER array contains four magnetometers and spans across the geomagnetic equator from L of 1 to an L of 1.4. In addition to filling the largest land-based gap in global magnetometer coverage, the AMBER array will address two fundamental areas of space physics: (1) the processes governing electrodynamics of the equatorial ionosphere as a function of latitude (or L-shell), local time, longitude, magnetic activity, and season, and (2) ULF pulsation strength and its connection with equatorial electrojet strength at low/ mid-latitude regions. Satellite observations show unique equatorial ionospheric structures in the African sector, though these have not been confirmed by observation from the ground due to lack of ground-based instruments in the region. In order to have a complete global understanding of equatorial ionosphere motions, deployment of ground-based magnetometers in Africa is essential. One focus of IHY is the deployment of networks of small instruments, including the development of research infrastructure in developing nations through the United Nations Basic Space Science (UNBSS) Small Instrument Array. Therefore, AMBER magnetometer array in partnership with parallel US funded GPS receivers in Africa will allow us to understand the electrodynamics that governs equatorial ionosphere motions. While AMBER routinely observes the F region plasma drift mechanism (E 9 B drift), the GPS stations will monitor the structure of plasma at low/midlatitudes in the African sectors. In addition to new scientific discoveries and advancing the space science research into Africa by establishing scientific collaborations between scientists in the developing and developed nations, the AMBER project also contributes to developing the basic science of heliophysics through cross-disciplinary studies of universal process. This includes the creation of sustainable research/training infrastructure within the developing nations (Africa).

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The Southern Hemisphere and equatorial region ionization response for a 22 September 1999 severe magnetic storm

Cited by 43 publications

References 20 publications

GPS Ionospheric Total Electron Content and Scintillation Measurements during the October 2003 Magnetic Storm

GPS Ionospheric Total Electron Content and Scintillation Measurements during the October 2003 Magnetic Storm

Ionospheric temporal and spatial variations during the 18 August 2003 storm over China

African Meridian B-Field Education and Research (AMBER) Array

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