Case studies of the propagation characteristics of auroral TIDS with EISCAT CP2 data using maximum entropy cross-spectral analysis

Y., S.; Schlegel, K.; Xu, Jisheng

doi:10.1007/s00585-998-0161-3

Cited by 39 publications

(30 citation statements)

References 23 publications

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“…Taking into account any deviation from the equatorward propagation, these estimated values correspond to much smaller phase velocities. On the other hand, whenever the spaced beam reception method was used at the EISCAT incoherent scatter station, the determined phase velocities never exceeded 400 m/s (Ma et al, 1998). Measurements from the MU radar gave even smaller estimates (averaging about 240 m/s) (Oliver et al, 1997), while Super-DARN (Hall et al, 1999) velocities were similar to TID velocities.…”

Section: Auroral Activity and Height Enhancementsmentioning

confidence: 91%

“…In the cases presented above, the propagation velocity ranges from 270 m/s to 1280 m/s, which again correspond better to the meridional velocity component of the disturbance front than to the true phase velocity propagation. But since deviation of the azimuth of TID propagation from the equatorward direction to the westward direction by 10-20 • , on average, has been reported (Oliver et al, 1997;Ma et al, 1998;Hall et al, 1999;Afraimovich et al, 2000), the true phase velocities may be much smaller.…”

Section: Auroral Activity and Height Enhancementsmentioning

confidence: 93%

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On the nature of nighttime ionisation enhancements observed with the Athens Digisonde

Tsagouri

Belehaki

2002

Ann. Geophys.

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Abstract. True height electron density profiles observed with the Athens Digisonde were analyzed together with geomagnetic data indices for six magnetic storms in September and October 2000 in an effort to define the ionospheric structure during events of nighttime ionisation enhancements and to discuss the physical processes that may cause them. An upwelling of the F2-layer, limited to the dark hemisphere, was evident in all storm events as the ionospheric response to enhanced geomagnetic activity, but nighttime positive effects and nighttime height enhancements are attributed to two distinct mechanisms, according to our findings. Height enhancements are wave-like disturbances and the time delay of their occurrence at middle latitudes depends on the increase rate of the AE index, and consequently, on the rate that the solar wind input energy dissipates in the auroral ionosphere. Thus, they most probably originated in the auroral oval region and propagated toward the equator-like TID disturbances, with a periodicity that depends on the ionisation density. On the other hand, foF2 increases do not share the same wavy appearance, which could mean that they are not connected to TIDs and are not of auroral oval origin. The increased nighttime density can only be speculated to be due to increased downward fluxes from the plasmasphere.

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Section: Auroral Activity and Height Enhancementsmentioning

confidence: 91%

Section: Auroral Activity and Height Enhancementsmentioning

confidence: 93%

On the nature of nighttime ionisation enhancements observed with the Athens Digisonde

Tsagouri

Belehaki

2002

Ann. Geophys.

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“…This chain of GPS stations is about 2000 km from the southern boundary of the auroral source of TIDs which is produced during geomagnetic disturbances. TIDs that are generated once this source is produced travel equatorward with the velocity of the order of 300-400 m/s (Francis, 1973;Maeda and Handa, 1980;Hunsucker, 1982;Haykowicz and Hunsucker, 1987;Ma et al, 1998;Hocke and Schlegel, 1996;Ho et al, 1998;Balthazor and Moffett, 1999;Hall et al, 1999;Afraimovich et al, 2000b).…”

Section: Characteristics Of the Tid Spectrum As A Function Of The Unimentioning

confidence: 99%

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

et al. 2001

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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.Correspondence to: E. L. Afraimovich (afra@iszf.irk.ru)

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“…It demonstrates the characteristics of ionospheric disturbances using GPS observations, which fully take the satellite motion into account. In this paper, the propagation velocities are obtained through maximum entropy cross spectral analysis method (Ma et al, 1998). The average horizontal velocities are estimated as about 313,676,194, and 212 m s −1 in Fig.…”

Section: Resultsmentioning

confidence: 99%

Study of ionospheric disturbances over the China mid- and low-latitude region with GPS observations

Ning

Tanida

2018

Ann. Geophys.

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Abstract. Ionospheric disturbances constitute the main restriction factor for precise positioning techniques based on global positioning system (GPS) measurements. Simultaneously, GPS observations are widely used to determine ionospheric disturbances with total electron content (TEC). In this paper, we present an analysis of ionospheric disturbances over China mid-and low-latitude area before and during the magnetic storm on 17 March 2015. The work analyses the variation of magnetic indices, the amplitude of ionospheric irregularities observed with four arrays of GPS stations and the influence of geomagnetic storm on GPS positioning. The results show that significant ionospheric TEC disturbances occurred between 10:30 and 12:00 UT during the main phase of the large storm, and the static position reliability for this period are little affected by these disturbances. It is observed that the positive and negative disturbances propagate southward along the meridian from mid-latitude to low-latitude regions. The propagation velocity is from about 200 to 700 m s −1 and the amplitude of ionospheric disturbances is from about 0.2 to 0.9 TECU min −1 . Moreover, the position dilution of precession (PDOP) with static precise point positioning (PPP) on storm and quiet days is 1.8 and 0.9 cm, respectively. This study is based on the analysis of ionospheric variability with differential rate of vertical TEC (DROVT) and impact of ionospheric storm on positioning with technique of GPS PPP.

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Case studies of the propagation characteristics of auroral TIDS with EISCAT CP2 data using maximum entropy cross-spectral analysis

Cited by 39 publications

References 23 publications

On the nature of nighttime ionisation enhancements observed with the Athens Digisonde

On the nature of nighttime ionisation enhancements observed with the Athens Digisonde

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

Study of ionospheric disturbances over the China mid- and low-latitude region with GPS observations

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