Simultaneous VHF radar backscatter and ionosonde observations of low-latitude E region

Patra, Amit; Sripathi, S.; Rao, P. B.; Subbarao, K.

doi:10.5194/angeo-23-773-2005

Cited by 18 publications

(32 citation statements)

References 27 publications

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“…As is evident from these figures, FAIs occurrence and SNR both are poorly correlated with f b E s (correlation coefficients are −0.051 and −0.107, respectively) and fairly well correlated with (f t E s −f b E s ) (correlation coefficients are 0.596 and 0.573, respectively). These results are consistent with those reported earlier by Patra et al (2005). The present results show that the occurrence rate of FAIs also has a similar relationship.…”

Section: Daytime Irregularitiessupporting

confidence: 94%

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: Daytime Irregularitiessupporting

confidence: 94%

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

et al. 2008

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“…3, 4, and 6, we obtained a general picture of sporadic E during QP echo occurrences. The development of spatial inhomogeneities, as evidenced by the difference between the electron densities corresponding to the foEs and fbEs, is necessary for the onset of QP echoes, which confirmed the results of Ogawa et al (2002) at mid-latitudes, but did not agree well with the recent findings of Patra et al (2005) at low latitudes. Tentatively, there seems to be a threshold level for foEs and n, in order for the radar echoes to appear.…”

Section: Quasi-periodic Echoescontrasting

confidence: 81%

“…Ogawa et al (2002) found a good correlation between the MU radar backscatter and increases in foEs-fbEs in the ionograms obtained at the radar site, which is separated by 130 km from the radar scattering volume. On the other hand, Patra et al (2005) found a rather poor correlation between coherent backscatter obtained with the Gadanki MST radar (79.2 • E, 13.5 • N) and ftEs-fbEs obtained at Sriharikota (80.1 • E,13.7 • N) during the night. In their experiment, the separation between the ionosonde and radar backscattering volume was about 100 km.…”

Section: Quasi-periodic Echoesmentioning

confidence: 74%

Simultaneous observation of sporadic E with a rapid-run ionosonde and VHF coherent backscatter radar

et al. 2006

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Abstract. During the SEEK 2 rocket campaign, ionograms were recorded every minute at the Yamagawa Radio Observatory at about 90 km west of the region monitored by a VHF (very high frequency) coherent backscatter radar. Sporadic E-layer parameters, which include the critical (foEs) and blanketing (fbEs) frequencies, the layer height (h Es), and the width of the range spread of sporadic E-traces, were compared with RTI (range-time-intensity) plots of VHF quasiperiodic (QP) and continuous coherent backscatter echoes. A close relationship was found between the appearance of QP echoes in the RTI plots and the level of spatial inhomogeneity in sporadic E plasma, signified here by the difference between foEs and fbEs. During QP echo events, foEs increased while fbEs decreased, so that the difference foEs-fbEs was enhanced, indicating the development of strong spatial structuring in electron density within a sporadic E-layer. On the other hand, increases in sporadic E range spreading also correlated with the occurrence of QP echoes but the degree of correlation varied from event to event. Continuous radar echoes were observed in association with low altitude sporadic E-layers, located well below 100 km and at times as low as 90 km. During the continuous echo events, both foEs and fbEs were less variable, and the difference foEs-fbEs was small and not as dynamic as in the QP echoes. On the other hand, the Es-layer spread intensified during continuous echoes, which means that some patchiness or corrugation in those low altitude layers is also necessary for the continuous backscatter echoes to take place.

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“…The development of spatial in-homogeneity as evidenced by the difference in f o E S and f b E S is necessary for the onset of QP echoes which confirmed the results of Ogawa et al (2002) at mid latitudes, but did not agree well with the recent findings of Patra et al (2005) and the present observations at low latitudes. Patra et al (2005) reported that the most intense echo is below the virtual height of E S layer during daytime while it is either above or below during night. The strength of the FAI is better correlated with the top penetration frequency f t E S and f b E S during night than during day.…”

Section: Summary and Discussioncontrasting

confidence: 99%

HF Doppler radar observations of sporadic E at an Indian low latitude station, Visakhapatnam

2009

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Abstract. 5.5 MHz HF Doppler radar observations of Sporadic E over an Indian low latitude station, Visakhapatnam (17.7 • N, 83.3 • E and Dip 20 • ) with 10 s resolution showed quasi-periodic variations of the echo strength and Doppler velocity variations with periods of a few minutes to a few tens of minutes. The echo strength and Doppler velocity variations with time in different range bins of the E S echo showed variations which are some times similar and some times significantly different in successive range bins at intervals of 7.5 km. The E S echo occurs with the height of maximum echo strength in the range of 100 km to 120 km and some times at 130 km. The altitude variation of the average Doppler velocity is highly variable and the height of maximum echo strength is not the same as the height of maximum Doppler velocity. Observations of E S echoes at different times of the day are presented to bring out the differences between the day and night time E S echoes. The relationship between Radar and E S parameters derived from Ionograms is poorer than that of mid latitudes which is quite consistent with the expectations based on gradient drift instability.

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Simultaneous VHF radar backscatter and ionosonde observations of low-latitude E region

Cited by 18 publications

References 27 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

Simultaneous observation of sporadic E with a rapid-run ionosonde and VHF coherent backscatter radar

HF Doppler radar observations of sporadic E at an Indian low latitude station, Visakhapatnam

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