Statistical characteristics of VHF radar observations of low latitude E-region field-aligned irregularities over Gadanki

Patra, Amit; Sripathi, S.; Sivakumar, Venkataraman; Rao, P. B.

doi:10.1016/j.jastp.2004.07.032

Cited by 39 publications

(74 citation statements)

References 40 publications

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“…Observations on E region FAIs from Kototabang, however, have been limited so far. Echo occurrence and spectral characteristics revealed from these observations have been found to be close to those observed in mid-latitudes and distinctly different from those of equatorial electrojet (for details, see Chau et al, 2002;Patra et al, 2004). It may be noted that these radars are located in the 6-11 • magnetic latitude belt.…”

Section: Introductionsupporting

confidence: 59%

“…Patra et al (2004) made a detailed study on the diurnal variation of echo occurrence and spectral parameters based on Gadanki observations and compared it in detail with those reported by Chau et al (2002). These reports showed that during noontime, while the echoes disappear at Piura, they occur quite frequently at Gadanki (Chau et al, 2002;Patra et al, 2004). Patra et al (2004) showed that SNR of daytime echoes are comparable to or sometimes more than those of nighttime echoes (their Figs.…”

Section: Introductionmentioning

confidence: 90%

“…Chau et al (2002) have made a detailed investigation on the diurnal and seasonal variations of low-latitude E region FAIs based on Piura radar observations. Patra et al (2004) made a detailed study on the diurnal variation of echo occurrence and spectral parameters based on Gadanki observations and compared it in detail with those reported by Chau et al (2002). These reports showed that during noontime, while the echoes disappear at Piura, they occur quite frequently at Gadanki (Chau et al, 2002;Patra et al, 2004).…”

Section: Introductionmentioning

confidence: 91%

“…These reports showed that during noontime, while the echoes disappear at Piura, they occur quite frequently at Gadanki (Chau et al, 2002;Patra et al, 2004). Patra et al (2004) showed that SNR of daytime echoes are comparable to or sometimes more than those of nighttime echoes (their Figs. 4 and 5).…”

Section: Introductionmentioning

confidence: 93%

“…4 and 5). Since both the locations are well outside the electrojet belt and have near similar magnetic latitude, Patra et al (2004) attributed the observed difference to varying wind fields at the two geographically different locations. However, no further study has been made to account for the differences.…”

Section: Introductionmentioning

confidence: 99%

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Seasonal variation of low-latitude E-region plasma irregularities studied using Gadanki radar and ionosonde

et al. 2008

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Abstract. In this paper, we present seasonal variation of E region field-aligned irregularities (FAIs) observed using the Gadanki radar and compare them with the seasonal variation of E s observed from a nearby location SHAR. During daytime, FAIs occur maximum in summer and throughout the day, as compared to other seasons. During nighttime, FAIs occur equally in both summer and winter, and relatively less in equinoxes. Seasonal variations of E s (i.e. f t E s and f b E s ) show that the daytime activity is maximum in summer and the nighttime activity is maximum in equinoxes. No relation is found between FAIs occurrence/SNR and f t E s /f b E s . FAIs occurrence, however, is found to be related well with (f t E s −f b E s ). This aspect is discussed in the light of the present understanding of the mid-latitude E s -FAIs relationship. The seasonal variations of FAIs observed at Gadanki are compared in detail with those of Piura, which show a significant difference in the daytime observations. The observed difference has been discussed considering the factors governing the generation of FAIs.

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Section: Introductionsupporting

confidence: 59%

Section: Introductionmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

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Seasonal variation of low-latitude E-region plasma irregularities studied using Gadanki radar and ionosonde

et al. 2008

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First results on low‐latitude E and F region irregularities obtained using the Gadanki Ionospheric Radar Interferometer

et al. 2014

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A 30 MHz radar has recently been established at Gadanki (13.5°N, 79.2°E; 6.5°N magnetic latitude) to make unattended observations of the ionospheric field-aligned irregularities (FAI). This radar, called the Gadanki Ionospheric Radar Interferometer (GIRI), has been designed to have scanning capability of 100°in the east-west plane perpendicular to Earth's magnetic field and interferometry/imaging system to study drifts and spatial distribution of plasma irregularities at both large and small scales. In this paper, we present the first results on the E and F region FAI made using the scanning capability of the GIRI. Daytime observations of E region FAI show type 2 echoes with velocities predominantly upward northward (downward-southward) at altitudes >100 km (<100 km) and westward (eastward) in the forenoon (afternoon) with signature of tidal wind field. F region irregularities show bottom-type, bottomside and plume structures with close resemblance to those observed over the magnetic equator. Observations made with the east-west scanning capability have been used to study the origin, evolution, and drift of the FAI for the first time from Gadanki. Eastward drifts are estimated to be 90-210 m s À1 during 20-24 LT. Upward velocity as large as 500 m s À1 has been observed in the initial phase of the plume structures. Intriguingly, downward velocity as large as 60 m s À1 has also been observed in the plumes, displaying descending pattern, observed in the early evening hours. These results are presented and discussed in the light of current understanding of low-latitude plasma irregularities, and future prospects of GIRI are outlined.

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On the governing dynamics of the VHF radar echoes from the mesosphere and collision‐dominated lower E region over Gadanki (13.5°N, 79.2°E)

et al. 2017

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In the present communication, the role of neutral dynamical processes in governing the morphology and seasonal variations of daytime VHF radar echoes from the mesosphere and the collision‐dominated lower E region is discussed. While the seasonal variations of mesospheric echo occurrence show semiannual variation with their maxima in the equinoxes, the occurrence of E region echoes shows strong annual variation peaking in the summer with two secondary maxima identical to semiannual variation of the mesospheric echoes. The occurrence rates of the E region echoes, however, display year‐to‐year variability. Semiannual variations in the occurrence of low‐latitude mesospheric echoes are closely linked with similar variations in the occurrences of temperature inversion, large wind shear, tides, and gravity wave activities in the same height region. In the case of E region echoes, the summer maximum and equinoctial secondary maxima are found to be linked with similar variations in wind and wind shear, Es activity, tidal, and gravity wave activities. Further, the summer maximum is found to be strongly correlated with that of meteor flux and nonmigrating diurnal tide. This finding is significant given the fact that such wind field in the presence of metallic ions could form both Es and field‐aligned irregularities. The present results show that tides and gravity waves are the most important dynamical factors governing the morphology and seasonal variations of the mesospheric as well as lower E region echoes observed over Gadanki. These results are discussed in the light of current understanding on the dynamical coupling of the mesosphere and lower E region through tides and gravity waves.

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Statistical characteristics of VHF radar observations of low latitude E-region field-aligned irregularities over Gadanki

Cited by 39 publications

References 40 publications

Seasonal variation of low-latitude E-region plasma irregularities studied using Gadanki radar and ionosonde

Seasonal variation of low-latitude E-region plasma irregularities studied using Gadanki radar and ionosonde

First results on low‐latitude E and F region irregularities obtained using the Gadanki Ionospheric Radar Interferometer

On the governing dynamics of the VHF radar echoes from the mesosphere and collision‐dominated lower E region over Gadanki (13.5°N, 79.2°E)

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