A comparison of ionospheric vertical drift velocities measured by Digisonde and Incoherent Scatter Radar at the magnetic equator

Bertoni, F.; Batista, I. S.; Abdu, M. A.; Reinisch, B. W.; Kherani, E. A.

doi:10.1016/j.jastp.2006.01.002

Cited by 46 publications

(50 citation statements)

References 19 publications

(29 reference statements)

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“…Abdu et al: Equatorial Spread F initiation by gravity waves over Millstone Hill, obtaining excellent agreement. Also, good agreement has been found between the vertical drift calculated from the true heights as d(h F )/dt and that obtained from Doppler data (Abdu et al, 2006b) using the digisonde drift explorer software (Scali et al, 1995) as well as that measured by the Jicamarca incoherent scatter radar (Bertoni et al, 2006). The true heights were used also to extract the gravity wave oscillations at specific plasma frequencies (as explained later).…”

Section: Experimental Datamentioning

confidence: 65%

“…It has been noted from statistical analysis of the data in the Brazilian sector that an evening vertical drift in excess of 38 m/s (on an average) is required as a precondition for the occurrence of well extended (>1000 km above equator) topside bubbles (e.g., Abdu et al, 2006). We note in Fig.…”

Section: Signatures Of Gravity Waves and Evening Prereversal Electricmentioning

confidence: 77%

“…The peak velocities of the PRE (the V yp , occurring at 18:00 LT/21:00 UT), that is, 18 m/s in the examples in Fig. 1, are considered to be insufficient (or marginal) for well extended bubble development (Abdu et al, 1983(Abdu et al, , 2006Fejer et al, 1999), and hence they appear to be somewhat ideal for evaluating any possible contribution to the ESF generation arising from GW effects. if plasma depletion was already evolving by this time.…”

Section: Signatures Of Gravity Waves and Evening Prereversal Electricmentioning

confidence: 99%

“…A large eastward thermospheric wind in the evening could produce large vertical drift and hence the F layer rise to higher levels thereby enhancing significantly the spread F instability growth rate by Rayleigh-Taylor instability mechanism. The requirements on the PRE/evening vertical drift and the height of the F layer for the spread F "on" and "off" conditions and its varying growth rates and intensities have been widely discussed in the literature (e.g., Farley et al, 1970;Abdu et al, 1983Abdu et al, , 2006Fejer et al, 1999;Sultan, 1996;Sastri et al, 1997). Models have been developed to investigate the effects of the evening zonal electric fields, F layer bottom-side density gradients, and zonal, meridional and vertical winds on the ESF instability development conditions (e.g., Zalesak et al, 1982;Sekar et al, 1994;Maruyama, 1988;Keskinen et al, 2003;Kudeki et al, 2007;Kherani et al, 2009a).…”

Section: Introductionmentioning

confidence: 99%

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Gravity wave initiation of equatorial spread F/plasma bubble irregularities based on observational data from the SpreadFEx campaign

et al. 2009

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Abstract. The data from ground based experiments conducted during the 2005 SpreadFEx campaign in Brazil are used, with the help of theoretical model calculations, to investigate the precursor conditions, and especially, the role of gravity waves, in the instability initiation leading to equatorial spread F development. Data from a digisonde and a 30 MHz coherent back-scatter radar operated at an equatorial site, Sao Luis (dip angle: 2.7 • ) and from a digisonde operated at another equatorial site (dip angle: −11.5 • ) are analyzed during selected days representative of differing precursor conditions of the evening prereversal vertical drift, F layer bottom-side density gradients and density perturbations due to gravity waves. It is found that radar irregularity plumes indicative of topside bubbles, can be generated for precursor vertical drift velocities exceeding 30 m/s even when the precursor GW induced density oscillations are marginally detectable by the digisonde. For drift velocities ≤20 m/s the presence of precursor gravity waves of detectable intensity is found to be a necessary condition for spread F instability initiation. Theoretical model calculations show that the zonal polarization electric field in an instability development, even as judged from its linear growth phase, can be significantly enhanced under the action of perturbation winds from gravity waves. Comparison of the observational results with the theoretical model calculations provides evidence for gravity wave seeding of equatorial spread F.

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Section: Experimental Datamentioning

confidence: 65%

Section: Signatures Of Gravity Waves and Evening Prereversal Electricmentioning

confidence: 77%

Section: Signatures Of Gravity Waves and Evening Prereversal Electricmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Gravity wave initiation of equatorial spread F/plasma bubble irregularities based on observational data from the SpreadFEx campaign

et al. 2009

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“…, us ing changes in the height of the layer as mea sure by the digisonde at Jicamarca (Bertoni et al 2006). A ver ti cal drift of 22 m s -1 con firms the well formed anom aly ob served by TIP.…”

Section: Equa To Rial Anom Alymentioning

confidence: 96%

Campaign Investigation of Ionospheric Plasma Irregularities in Sporadic E Region Using FORMOSAT-3/COSMIC Satellite and Chung-Li 30 MHz Coherent Radar

Wang¹,

Chu²,

Su³

et al. 2009

Terr. Atmos. Ocean. Sci.

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AB STRACTThe Tiny Ion o spheric Pho tom e ter (TIP) on the Con stel la tion Ob serv ing Sys tem for Me te o rol ogy, Ion o sphere, and Cli mate (FORMOSAT-3/COS MIC) char ac ter izes the night time ion o sphere us ing 135.6-nm ra di a tive re com bi na tion emis sion. TIP mea sures hor i zon tal struc ture of the ion o sphere with high pre ci sion and high spa tial res o lu tion. Lat i tu di nal, lon gi tu di nal, and tem po ral dis tri bu tion of the night time ion o sphere is spec i fied. We pres ent a re view of ion o spheric ob ser va tions made with TIP dur ing the first five months of op er a tion. Com par i sons are made with other ion o spheric sen sors in or der to val i date the TIP ob ser va tions and to dem on strate TIP res o lu tion and sen si tiv ity per for mance. Equa to rial anom a lies ob served by TIP are com pared with es ti mates of the E ´ B ver ti cal drift dur ing the post-sun set pre-re ver sal en hance ment in the Pe ru vian sec tor. Low lat i tude ir reg u lar ity struc tures ob served by TIP are com pared with mea sure ments from ground-based sen sors in clud ing: im ag ing pho tom e ters, ionosonde, and UHF scin til la tion re ceiv ers. De tailed mea sure ments of low lat i tude den sity de ple tion depth and width are pro vided. Global ion o spheric mor phol ogy ob served by TIP is com pared with sim i lar observations by COSMIC radio occultation, and the GAIM model. The complexity of the underlying neutral winds is revealed by the TIP ionospheric morphology. Atmos. Ocean. Sci., 20, 227-235, doi: 10.3319/TAO.2008.01.18.02(F3C) IN TRO DUC TIONThe Con stel la tion Ob serv ing Sys tem for Me te o rol ogy, Ion o sphere, and Cli mate (FORMOSAT-3/COS MIC) uses the Tiny Ion o spheric Pho tom e ter (TIP) to char ac ter ize the night time ion o sphere di rectly be low each space craft. TIP is a com pact, nar row-band, and ul tra vi o let pho tom e ter op erat ing at the 135.6-nm wave length (Dymond et al. 2000;Kalmanson et al. 2004). This emis sion is pro duced by recom bi na tion of O+ ions and elec trons, which is the nat u ral de cay pro cess for the ion o sphere. At night, the strength of the emis sion is pro por tional to the square of the elec tron den sity in te grated over the line of sight (Dymond et al. 1997).The prin ci pal sci ence mis sion of TIP is to mea sure the hor i zon tal struc ture of the nighttime ion o sphere. When the hor i zon tal ion o spheric struc ture is mea sured with suf ficient pre ci sion, it can be com bined with ver ti cal struc ture mea sured by GPS ra dio occultations to re con struct high accu racy elec tron den sity dis tri bu tions in the ion o sphere. TIP is or ders of mag ni tude more sen si tive than its FUV pre deces sors, such as SSULI, LORAAS, SSUSI, GUVI, and IM AGE (Thonnard et al. 1999;Mende et al. 2000;Budzien et al. 2002;Paxton et al. 2003), and pro vides re mark able detail on ion o spheric struc tures un de tected by other FUV sensors. A sin gle TIP pass pro vides a la titudinal snap shot of the equa to rial anom aly and ad ja cent mi...

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Low‐latitude ionospheric height variation as observed by meridional ionosonde chain: Formation of ionospheric ceiling over the magnetic equator

et al. 2014

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A multipoint ionosonde observation campaign was conducted along the magnetic meridional plane in Southeast Asia to study ionosphere‐thermosphere coupling. One station was near the magnetic equator and two of the other stations were at off‐equatorial latitudes (∼10° magnetic latitude). The daytime ionospheric peak height (hmF2) was analyzed for each season during the solar minimum years, 2006–2007 and 2009. The peak height increased for ∼3 h after sunrise at the magnetic equator and off‐equatorial latitudes, as expected from the daytime upward E × B drift. The apparent upward drift at the magnetic equator ceased before noon, while the drift at the off‐equatorial latitudes continued upward and the layer height exceeded the equatorial height around noon. The noontime limited layer peak height at the magnetic equator, which was termed the ionospheric ceiling, did not depend on the season, while the maximum peak height at the off‐equatorial latitudes largely varied with each season. Numerical modeling using the SAMI2 code was conducted and the features of the ionospheric ceiling were reproduced quite well. The dynamical parameters provided by the SAMI2 modeling runs showed that the ionospheric ceiling is formed by the field‐aligned plasma diffusion, which is a part of the fountain effect.

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A comparison of ionospheric vertical drift velocities measured by Digisonde and Incoherent Scatter Radar at the magnetic equator

Cited by 46 publications

References 19 publications

Gravity wave initiation of equatorial spread F/plasma bubble irregularities based on observational data from the SpreadFEx campaign

Gravity wave initiation of equatorial spread F/plasma bubble irregularities based on observational data from the SpreadFEx campaign

Campaign Investigation of Ionospheric Plasma Irregularities in Sporadic E Region Using FORMOSAT-3/COSMIC Satellite and Chung-Li 30 MHz Coherent Radar

Low‐latitude ionospheric height variation as observed by meridional ionosonde chain: Formation of ionospheric ceiling over the magnetic equator

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