Magnetic conjugate point observations of kilometer and hundred‐meter scale irregularities and zonal drifts

Abstract

[1] The Conjugate Point Equatorial Experiment (COPEX) campaign was carried out in Brazil, between October and December 2002, to study the conjugate nature of plasma bubble irregularities and to investigate their generation mechanisms, development characteristics, spatial-temporal distribution, and dynamics. In this work we will focus mainly on the zonal spaced GPS (1.575 GHz) and VHF (250 MHz) receivers' data collected simultaneously at two magnetic conjugate sites of the COPEX geometry: Boa Vista and Campo Grande. These GPS/VHF receivers were set up to detect the equatorial scintillations and to measure ionospheric scintillation pattern velocities. Then, the zonal irregularity drift velocities were estimated by applying a methodology that corrects the effects caused by vertical drifts and geometrical factors. The results reveal the coexistence of kilometer-(VHF) and hundred-meter-scale (GPS L-band) irregularities into the underlying depletion structure. Over the conjugate site of Campo Grande, the average zonal velocity at VHF seems to be consistently larger than the estimated GPS velocities until ∼0200 UT, whereas over Boa Vista the irregularities detected from both techniques are drifting with comparable velocities. The hundred-meter-scale structures causing L-band scintillations appear to be drifting with comparable velocities over both the conjugate sites, whereas the kilometer-scale structures are drifting over Campo Grande with larger average velocities (before 0300 UT). Complementary data of ionospheric parameters scaled from collocated digital ionosondes are used in the analysis to explain differences/similarities on the scintillation/zonal drift results.

Statistical characteristics of low-latitude ionospheric scintillation over China

“…Additional details about the equation please refer to for example Kil et al (2000), Ledvina et al (2004) andde Paula et al (2010).…”

“…Additional details about the calculation of irregularity drifts using spatially separated GPS receivers have been presented in many studies (Ledvina et al, 2004;Otsuka et al, 2006;Muella et al, 2008Muella et al, , 2009. Briefly, through calculating the scintillation pattern velocity with the cross correlation method (only the data with S 4 > 0.2 and elevation angle > 30°are used), the zonal drifts are computed by taking the equation (Ledvina et al, 2004;de Paula et al, 2010),…”

Ionospheric plasma bubbles observed concurrently by multi‐instruments over low‐latitude station Hainan

“…Especially, given Fresnel considerations, GPS L band (1.575 GHz) scintillation is sensitive to ~ 360–400 m for an irregularity layer at 350 km in the ionosphere, and VHF (260 MHz) scintillation is sensitive to ∼1 km [ Basu et al ., ; Kintner et al ., ]. Extensive studies of the properties of VHF and GPS scintillations have been reported by many authors [e.g., Muella et al ., ; de Paula et al ., ; Olwendo et al ., ]. The observations by Yeh et al .…”

Mesospheric gravity waves and ionospheric plasma bubbles observed during the COPEX campaign

“…The COPEX campaign was conducted from October to December 2002 (Reinisch et al, 2004;Batista et al, 2008;McNamara et al, 2008;Abdu et al, 2009b;MacDougall et al, 2009;Sobral et al, 2009;de Paula et al, 2010). At geomagnetically conjugate stations, Boa Vista and Campo Grande (20:50 3 S; 54:70 3 W, dip angle 21:0 3 S), airglow imagers were installed.…”