Morphological study of the field-aligned E-layer irregularities observed by the Gadanki VHF radar

Chen, Pan; Rao, P. B.

doi:10.5194/angeo-22-3799-2004

Cited by 5 publications

(4 citation statements)

References 31 publications

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“…Echoing layers having thickness of 2-3 km and descent rate of ∼0.5 m/s have already been reported from Gadanki observations (Choudhary et al, 1996;Patra et al, 2004;Pan and Rao, 2004). However, such echoes during daytime have been observed at Gadanki only.…”

Section: Discussionmentioning

confidence: 82%

Gadanki radar observations of daytime E region echoes and structures extending down to 87 km

et al. 2006

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Abstract.Observations of daytime E region echoes extending to altitudes as low as 87 km made using the Gadanki MST radar are presented. The echoing regions display descending layer resembling the characteristics of tidal winds and show structures with periods 2-4 min having both positive and negative slopes. At the center of the layer where strongest SNR is observed, the velocity is maximum and spectral width is minimum. At altitudes slightly above and below, where SNR is relatively low, velocity is low but spectral width is maximum. Daytime observations of echoes extending to such a low altitude and associated structures akin to nighttime quasi-periodic echoes throughout the observational period are the most significant results, not reported earlier from Gadanki and other locations. Other notable results are large SNR (as high as 15 dB) and spectral width (as high as 70 m/s) at the bottommost altitudes, where collisional damping of the plasma waves is significant.

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Section: Discussionmentioning

confidence: 82%

Gadanki radar observations of daytime E region echoes and structures extending down to 87 km

et al. 2006

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“…The morphology of these echoes was also described by Pan and Rao (2003), who showed that these echoes have different appearances at lower latitudes. Woodman et al (1991) and later had explained the generation of these echoes by atmospheric gravity waves modulating the sporadic E-layers (E s ) in such a way so as to make them locally unstable by the gradient drift instability.…”

Section: Introductionmentioning

confidence: 82%

Three-dimensional tracking of mid-latitude quasi-periodic E-region echoes observed with the Chung-Li VHF radar

Chen

Röttger

et al. 2005

Ann. Geophys.

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Abstract. This paper presents observations of low-altitude mid-latitude E-region irregularities obtained with the 52-MHz Chung-Li VHF radar. These are carried out in the interferometer mode to investigate the behavior of these irregularities over time and space. The observations presented here show the characteristics of type-II echoes noted by a negative slope, i.e. they are approaching the radar as a function of time. The range-time-intensity (RTI) plots obtained through power spectrum analysis reveal the quasi-periodic striations, which are known as LQP (Low-altitude QP) echoes. Our interferometer analysis allows one to investigate the motion (i.e. "tracking") of the LQP echo patches in three dimensions. This method is superior to just evaluating the variations of the echo power as a function of range and time in the standard RTI-plots. By applying this method, we show that the echo patches in different striations remain at almost the same altitude when we trace the isolated echoing regions until they disappear from the radar view. We further compare the rate of change of the range (range rate dR/dt) by two techniques: one by simply measuring the varying slope of the LQP echoes from RTI plot, the other by tracking the threedimensional locations of the LQP scatterers by using the interferometer technique. We finally prove that the changes in range as a function of time, deduced from the interferometer technique, are significantly correlated with those of the standard range rate analysis. However, the standard range rate analysis does not provide information about the correct location and the variation of the LQP irregularities. The threedimensional analysis, which we introduced for tracking individual striations, shows that LQP echo patches are confined to between 98 and 100 km altitude. This suggests that the irregularities which cause the LQP echoes drifted through the radar beam at approximately constant altitude, which we tend to attribute to a region of large-scale vertical shear of the horizontal wind.

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“…lat. 6.5°N) which is close to magnetic equator, multiple FAI layers were observed (e.g., Pan & Rao, 2004). Due to a lack of interferometry, the spatial structures of the FAI layers in horizontal plane were not investigated.…”

Section: Discussionmentioning

confidence: 99%

Wind Shear Driven Double Layer Structures of E‐Region Irregularities at Low Latitudes

Liu,

Sun,

et al. 2024

Geophysical Research Letters

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Previous theoretical simulations showed the generation of double‐layer structures of E‐region field‐aligned irregularities (FAIs). In this study, we report the double‐layer structures of E‐region FAIs observed by an all‐sky radar at low latitude Ledong (18.4°N, 109°E), China. These FAIs appeared at the altitudes ∼90 and 110 km respectively. Both layers displayed quasi‐periodic patterns with synchronized spatial features, that is, being manifested as spatially separated patches or wavelike structures over similar longitudes at the two layers simultaneously. The neutral wind observations revealed the existence of wind shears at two separated altitudes where the double FAI layers occurred. The two wind shears created two vertically separated sporadic E layers and possibly drove the generation of the double‐layer FAIs via gradient drift instability. The synchronized spatial features of the FAIs at the two layers could be modulated by gravity waves.

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Morphological study of the field-aligned E-layer irregularities observed by the Gadanki VHF radar

Cited by 5 publications

References 31 publications

Gadanki radar observations of daytime E region echoes and structures extending down to 87 km

Gadanki radar observations of daytime E region echoes and structures extending down to 87 km

Three-dimensional tracking of mid-latitude quasi-periodic E-region echoes observed with the Chung-Li VHF radar

Wind Shear Driven Double Layer Structures of E‐Region Irregularities at Low Latitudes

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