Signal frequency dependence of ionospheric amplitude scintillations

Bhattacharyya, A.; Rastogi, R. G.; Yeh, K. C.

doi:10.1029/rs025i004p00289

Cited by 8 publications

(9 citation statements)

References 26 publications

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“…Scintillations were also recorded on a L1 (1.575 GHz) signal transmitted from the geostationary satellite GSAT-10 (PRN 128) located at 83°E and received at MUM and at the equatorial station Trivandrum (TRV) located close to TIR. For weak scintillations produced by EPB irregularities, which are highly elongated in the direction of the geomagnetic field and hence may be considered to be essentially two dimensional, with a power law irregularity spectrum of the form Φ ΔN (q) ∝ q À m , the S 4 index is expected to show a signal frequency (f) dependence of the form: S 4 ∝ f À n , where n = (m + 3)/4 [Yeh and Liu, 1982;Bhattacharyya et al, 1990]. However, in the present case, S 4 on the 251 MHz signal exceeds 1, where the signal frequency dependence of S 4 departs significantly from the weak scintillation case.…”

Section: Latitudinal Variation Of Vhf and L-band Amplitude Scintillatmentioning

confidence: 99%

Development of intermediate‐scale structure at different altitudes within an equatorial plasma bubble: Implications for L‐band scintillations

et al. 2017

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An important aspect of the development of intermediate‐scale length (approximately hundred meters to few kilometers) irregularities in an equatorial plasma bubble (EPB) that has not been considered in the schemes to predict the occurrence pattern of L‐band scintillations in low‐latitude regions is how these structures develop at different heights within an EPB as it rises in the postsunset equatorial ionosphere due to the growth of the Rayleigh‐Taylor instability. Irregularities at different heights over the dip equator map to different latitudes, and their spectrum as well as the background electron density determine the strength of L‐band scintillations at different latitudes. In this paper, VHF and L‐band scintillations recorded at different latitudes together with theoretical modeling of the scintillations are used to study the implications of this structuring of EPBs on the occurrence and strength of L‐band scintillations at different latitudes. Theoretical modeling shows that while S4 index for scintillations on a VHF signal recorded at an equatorial station may be >1, S4 index for scintillations on a VHF signal recorded near the crest of the equatorial ionization anomaly (EIA) generally does not exceed the value of 1 because the intermediate‐scale irregularity spectrum at F layer peak near the EIA crest is shallower than that found in the equatorial F layer peak. This also explains the latitudinal distribution of L‐band scintillations. Thus, it is concluded that there is greater structuring of an EPB on the topside of the equatorial F region than near the equatorial F layer peak.

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Section: Latitudinal Variation Of Vhf and L-band Amplitude Scintillatmentioning

confidence: 99%

Development of intermediate‐scale structure at different altitudes within an equatorial plasma bubble: Implications for L‐band scintillations

et al. 2017

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“…Over the past two decades, many excellent reviews of scintillation theory and observations have been published (e.g., Aarons, 1982Aarons, , 1993Yeh and Liu, 1982;Basu, 1985, 1993;Rastogi, 1985, 1991;Bhattacharyya et al, 1990Bhattacharyya et al, , 1992. Comprehensive reviews of the physics of ionospheric irregularities can also be found in many articles (e.g., Keskinen and Ossakow, 1983;Heppner et al, 1993;Fejer, 1996).…”

Section: Introductionmentioning

confidence: 99%

Analysis of ionospheric scintillation spectra and TEC in the Chinese low latitude region

Ning

Yuan

2007

Earth Planet Sp

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GPS L-band scintillations and total electron content (TEC) were recorded at Sanya (18.33 • N, 109.52• E) during the period July 2004-July 2005. Automatic recorded raw digital scintillation data are analyzed to obtain the spectral characteristics of irregularities producing ionospheric scintillations and to estimate the correlation between amplitude scintillation and power spectral density. Concurrent measurements of TEC are used to analyze ROTI, defined as the standard deviation of the rate of change of TEC. The statistical results of S4 indices and power spectral indices indicate that the power spectral indices increase with S4 indices for weak scintillation (0.1 ≤ S4 < 0.3), but for moderate and strong scintillation, spectral indices tend to be saturated. In the analyzed data set, the ratio of ROTI/S4 is found to vary between 0.3 and 6, and the variation in estimated zonal drift velocities during geomagnetic quiet days (K p < 3) shows that the motion of the irregularities is highly variable in the initial phase of irregularity development. After about 22:00 LT, the estimated drift velocities tend to follow the same pattern.

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“…According to Bhattacharyya et al [1990], the frequency exponent (n) for weak scintillation is related to the power law index (m) for a two‐dimensional irregularity power spectrum through: therefore m can be estimated from n using the following equation: For the three examples in this paper, the power law indices of the intensity (m) are calculated and are equal to 5.88, 4.40, and 5.56, respectively.…”

Section: Sample Resultsmentioning

confidence: 99%

“…[14] According to Bhattacharyya et al [1990], the frequency exponent (n) for weak scintillation is related to the power law index (m) for a two-dimensional irregularity power spectrum through: n ¼ m þ 3 ð Þ =4; for 1 < m < 5; therefore m can be estimated from n using the following equation:…”

Section: Example 3: Prn06 (Svn03) Quiet Day (6 December 1989)mentioning

confidence: 99%

Ionospheric effects on GPS signals in the Arctic region using early GPS data from Thule, Greenland

El-Arini

Secan

Klobuchar³

et al. 2009

Radio Science

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[1] Thule, Greenland, is near the magnetic North Pole, and therefore any high-speed GPS data recorded there are of great potential import in specifying the severity of ionospheric effects on modern commercial navigation and ranging systems that must transit the polar latitudes. While there have now been many sets of GPS receiver data recorded at high latitudes, including GPS-IGS data routinely taken from Thule, Greenland, virtually all of these data have not been recorded at a high enough rate to measure the actual amplitude and phase scintillation effects. One notable exception is very early data taken from Thule, in the late 1980s and early 1990s, a period of high solar activity where data were taken from a L1/L2 dual-frequency receiver having the capability of tracking only one GPS satellite at a time, on both the L1 and the L2 channels with a data sampling rate of 20 Hz. The receiver phase-locked loop bandwidth was 16 Hz; thus, the sampling rate was not fast enough to insure that all the spectral components up to the receiver bandwidth were measured. We report on a new analysis of these ''old'' data illustrating that the rapid rates of change in total electron content (TEC) and high values of the amplitude scintillation index, S 4 , reported from these data are very relevant today with the advent of modern civilian aircraft routinely flying in the polar latitudes. For instance, we see a very high correlation between individual amplitude fades on the GPS L1 and L2 channels, indicating that users who suffer instantaneous signal loss on one frequency may not be able to use the secondary frequency to recover the GPS signal modulation, since it, too, will suffer an almost identical fade. Also, the occurrence of large, rapid changes in TEC, previously reported from these high-speed Thule GPS data, has been confirmed and may limit precise positioning in the polar cap latitudes.

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Signal frequency dependence of ionospheric amplitude scintillations

Cited by 8 publications

References 26 publications

Development of intermediate‐scale structure at different altitudes within an equatorial plasma bubble: Implications for L‐band scintillations

Development of intermediate‐scale structure at different altitudes within an equatorial plasma bubble: Implications for L‐band scintillations

Analysis of ionospheric scintillation spectra and TEC in the Chinese low latitude region

Ionospheric effects on GPS signals in the Arctic region using early GPS data from Thule, Greenland

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