First GPS-TEC evidence for the wave structure excited by the solar terminator

Afraimovich, É. L.

doi:10.1186/bf03352843

Cited by 53 publications

(49 citation statements)

References 21 publications

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“…Methods for calculating I s using GPS phase measurements are described in detail in (Calais et al, 2003;Afraimovich Published by Copernicus Publications on behalf of the European Geosciences Union. …”

Section: Methods Of Gps Data Analysesmentioning

confidence: 99%

“…We neglect the TEC data from low LOS elevation angles (less than 45 • ) to reduce errors due to conversion from slant to vertical TEC. To smooth the phase measurement noise and to select TEC variations dI(t) in the range of periods (of about 15 min) corresponding to the MS TWP one (Afraimovich, 2008), we firstly smooth the initial series with a time window of 2 min and then remove the linear trend with a window of about 20 min. The filter pass band at an amplitude level of 0.5 extends from 3 to 30 min.…”

Section: Methods Of Gps Data Analysesmentioning

confidence: 99%

“…If ST is considered to be a stable and repetitive source of AGWs, one can derive information on atmospheric conditions from a response of the medium to this input. Afraimovich (2008) has recently obtained the first GPS TEC evidence for the wave structure excited by ST movCorrespondence to: E. L. Afraimovich (afra@iszf.irk.ru) ing over the USA, Europe, and Japan. The author found two main types of the observed TEC disturbance: large-scale (LS) 60-min variations with amplitude of about 0.5-1 TECU and medium-scale (MS) 15-min variations with amplitude of about 0.05-0.1 TECU (TECU is 10 16 m −2 ).…”

Section: Introductionmentioning

confidence: 99%

“…To identify ST-generated wave packets it is insufficient to register the TEC time dependence (Afraimovich, 2008). Their spatial structure needs to be determined.…”

Section: Introductionmentioning

confidence: 99%

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The first GPS-TEC imaging of the space structure of MS wave packets excited by the solar terminator

et al. 2009

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Abstract. Using TEC measurements from the dense network of GPS sites GEONET, we have obtained the first GPS-TEC image of the space structure of medium-scale traveling wave packets (MS TWP) excited by the morning solar terminator (ST). We found that ST-generated wave packets have duration of about 1-2 h and time shift of about 1.5-6 h after the morning ST appearance at an altitude of 300 km. The TWP wave front extends along the morning ST line with the angular shift of about 20 • . The time period and wave-length of ST-generated wave packets are about 10-20 min and 200-300 km, respectively. The velocity of the TWP phase front traveling is of about 300 m/s. The space image of MS TWP manifests itself in pronounced anisotropy and high coherence over a long distance of about 2000 km.

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Section: Methods Of Gps Data Analysesmentioning

confidence: 99%

Section: Methods Of Gps Data Analysesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…To identify ST-generated wave packets it is insufficient to register the TEC time dependence (Afraimovich, 2008). Their spatial structure needs to be determined.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The first GPS-TEC imaging of the space structure of MS wave packets excited by the solar terminator

et al. 2009

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“…Nina and Cadež [2013] using DHO, France, transmitter signal at 23.4 kHz recorded at Belgrade Serbia, reported WLS of period 1 s to 90 min during ST passes. Afraimovich [2008] reported GPS TEC oscillations with periods of about 1 h at 100 km altitude. Our results also show similar and also higher period WLS than reported in previous works.…”

Section: Normal Day Wave-like Signaturesmentioning

confidence: 99%

Low‐mid latitude D region ionospheric perturbations associated with 22 July 2009 total solar eclipse: Wave‐like signatures inferred from VLF observations

Maurya¹,

Phanikumar

Singh³

et al. 2014

JGR Space Physics

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We present first report on the periodic wave-like signatures (WLS) in the D region ionosphere during 22 July 2009 total solar eclipse using JJI, Japan, very low frequency (VLF) navigational transmitter signal (22.2 kHz) observations at stations, Allahabad, Varanasi and Nainital in Indian Sector, Busan in Korea, and Suva in Fiji. The signal amplitude increased on 22 July by about 6 and 7 dB at Allahabad and Varanasi and decreased by about 2.7, 3.5, and 0.5 dB at Nainital, Busan, and Suva, respectively, as compared to 24 July 2009 (normal day). The increase/decrease in the amplitude can be understood in terms of modal interference at the sites of modes converted at the discontinuity created by the eclipse intercepting the different transmitter-receiver great circle paths. The wavelet analysis shows the presence of WLS of period~16-40 min at stations under total eclipse and of period~30-80 min at stations under partial eclipse (~85-54% totality) with delay times between~50 and 100 min at different stations. The intensity of WLS was maximum for paths in the partially eclipsed region and minimum in the fully eclipsed region. The features of WLS on eclipse day seem almost similar to WLS observed in the nighttime of normal days (e.g., 24 July 2009). The WLS could be generated by sudden cutoff of the photo-ionization creating nighttime like conditions in the D region ionosphere and solar eclipse induced gravity waves coming to ionosphere from below and above. The present observations shed additional light on the current understanding of gravity waves induced D region ionospheric perturbations.

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Advantage of wavelet technique to highlight the observed geomagnetic perturbations linked to the Chilean tsunami (2010)

et al. 2014

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The vertical component (Z) of the geomagnetic field observed by ground‐based observatories of the International Real‐Time Magnetic Observatory Network has been used to analyze the induced magnetic fields produced by the movement of a tsunami, electrically conducting sea water through the geomagnetic field. We focus on the survey of minutely sampled geomagnetic variations induced by the tsunami of 27 February 2010 at Easter Island (IPM) and Papeete (PPT) observatories. In order to detect the tsunami disturbances in the geomagnetic data, we used wavelet techniques. We have observed an 85% correlation between the Z component variation and the tide gauge measurements in period range of 10 to 30 min which may be due to two physical mechanisms: gravity waves and the electric currents in the sea. As an auxiliary tool to verify the disturbed magnetic fields, we used the maximum variance analysis (MVA). At PPT, the analyses show local magnetic variations associated with the tsunami arriving in advance of sea surface fluctuations by about 2 h. The first interpretation of the results suggests that wavelet techniques and MVA can be effectively used to characterize the tsunami contributions to the geomagnetic field and further used to calibrate tsunami models and implemented to real‐time analysis for forecast tsunami scenarios.

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First GPS-TEC evidence for the wave structure excited by the solar terminator

Cited by 53 publications

References 21 publications

The first GPS-TEC imaging of the space structure of MS wave packets excited by the solar terminator

The first GPS-TEC imaging of the space structure of MS wave packets excited by the solar terminator

Low‐mid latitude D region ionospheric perturbations associated with 22 July 2009 total solar eclipse: Wave‐like signatures inferred from VLF observations

Advantage of wavelet technique to highlight the observed geomagnetic perturbations linked to the Chilean tsunami (2010)

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