AMISR‐14: Observations of equatorial spread <i>F</i>

Rodrigues, F. S.; Nicolls, M. J.; Milla, Marco; Smith, Jason F.; Varney, R. H.; Strømme, A.; Martinis, C. R.; Arratia, Juan F.

doi:10.1002/2015gl064574

Cited by 14 publications

(16 citation statements)

References 38 publications

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“…Although both of them implicate ionospheric density irregularities in the postsunset F layer and degrade electromagnetic signal propagation, ESF and EPB are not identical. While ESF describes irregular signatures, especially on ionosonde's ionograms due to backscatter echo from and above the bottomside of the nighttime F layer, EPB refers to irregular plasma density depletions observed by satellites and radar backscatter (Jin et al, ; Rodrigues et al, ; Woodman & LaHoz, ) as well as by GPS TEC (Akala et al, ; Valladares & Chau, ; Zakharenkova & Astafyeva, ) in the topside ionosphere.…”

Section: Introductionmentioning

confidence: 99%

Longitudinal and Seasonal Variability of Equatorial Ionospheric Irregularities and Electrodynamics

Yizengaw

Groves

2018

Space Weather

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Over the past decades significant progresses have been done to understand the origin of seeding mechanisms of ionospheric irregularities. However, characterization of the global ionospheric irregularities as a function of local time, longitude, and season is still a challenge for the modeling community. In this review paper, using multiinstrument observations, we investigated the global irregularity distribution and its possible drivers that control the longitudinal and seasonal dependences. We demonstrated that forcing from lower thermosphere, like the localized tropospheric gravity waves seeding, may be responsible for the formation of strong longitudinal dependence of irregularity distribution. The location of Intertropical Convergence Zone that generate forceful thunderstorms and become favorable location for the launch of localized gravity waves may play an important role in the longitudinal dependence of irregularity distribution. Hence, incorporating the Intertropical Convergence Zone location into density irregularity modeling effort may provide important information to understand and characterize the longitudinal variability of irregularity distributions.Plain Language Summary The two major coupling processes, namely, (1) the vertical coupling that involves upward propagating atmospheric waves (forcing from below) and (2) magnetosphere-ionosphere coupling (forcing from above), cause for the initiation and development of ionospheric density irregularities that create favorable conditions for the creation of rapid amplitude and phase fluctuations of radio signals. On the other hand, application of radio wave is essential for our communication and navigation systems, either transmitted through the ionosphere for satellite communication and navigation or reflected off the ionosphere for HF and radar applications. This indicates that ionospheric density irregularities are as much an engineering concern as they are a scientific quest. The ionospheric irregularities, which are also not uniform globally, affect the integrity and performance of navigation and communication systems with different magnitudes at different longitudes. Hence, understanding the physics behind the longitudinal variability of equatorial ionospheric irregularities is essential to characterize and develop a model that can accurately capture the global distribution of ionospheric irregularities and its driving mechanisms.

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Section: Introductionmentioning

confidence: 99%

Longitudinal and Seasonal Variability of Equatorial Ionospheric Irregularities and Electrodynamics

Yizengaw

Groves

2018

Space Weather

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“…The depletions are moving at approximately 100 m/s, consistent with the movement of the irregularities from Rodrigues et al . []. The Milky Way can be seen in Figure as an increase in brightness that is much smaller in zonal width than the depletions.…”

Section: Methodsmentioning

confidence: 99%

“…Data from the JULIA imaging mode have been used to study ESF for many years now [ Hysell , ], while the AMISR‐14 system is relatively new and ESF has been reported only once [ Rodrigues et al ., ]. We start by looking at the data from the JULIA imaging mode on the night of 20–21 August 2014.…”

Section: Methodsmentioning

confidence: 99%

“…(top) The beam directions used in the AMISR‐14 experiment used in this study (taken from Rodrigues et al . []). (bottom) Three AMISR‐14 scans obtained with the multibeam experiment.…”

Section: Methodsmentioning

confidence: 99%

“…The detections of bottom‐type, bottomside, and topside ESF radar structures with AMISR‐14 are discussed in Rodrigues et al . []. A description, in more depth, of these structures is given by Woodman and La Hoz [] and Hysell and Burcham [].…”

Section: Methodsmentioning

confidence: 99%

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Concurrent observations at the magnetic equator of small‐scale irregularities and large‐scale depletions associated with equatorial spread F

et al. 2015

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In 2014 an all‐sky imager (ASI) and an Advanced Modular Incoherent Scatter Radar consisting of 14 panels (AMISR‐14) system were installed at the Jicamarca Radio Observatory. The ASI measures airglow depletions associated with large‐scale equatorial spread F irregularities (10–500 km), while AMISR‐14 detects small‐scale irregularities (0.34 m). This study presents simultaneous observations of equatorial spread F (ESF) irregularities at 50–200 km scale sizes using the all‐sky imager, at 3 m scale sizes using the JULIA (Jicamarca Unattended Long‐term Investigations of the Ionosphere and Atmosphere) radar, and at 0.34 m scales using the AMISR‐14 radar. We compare data from the three instruments on the night of 20–21 August 2014 by locating the radar scattering volume in the optical images. During this night no topside plumes were observed, and we only compare with bottomside ESF. AMISR‐14 had five beams perpendicular to the magnetic field covering ~200 km in the east‐west direction at 250 km altitude. Comparing the radar data with zenith ASI measurements, we found that most of the echoes occur on the western wall of the depletions with fewer echoes observed the eastern wall and center, contrary to previous comparisons of topside plumes that showed most of the echoes in the center of depleted regions. We attribute these differences to the occurrence of irregularities produced at submeter scales by the lower hybrid drift instability. Comparisons of the ASI observations with JULIA images show similar results to those found in the AMISR‐14 and ASI comparison.

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Radio-frequency imaging techniques for ionospheric, magnetospheric, and planetary studies

Fung

Benson

Galkin

et al. 2022

Magnetospheric Imaging

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AMISR‐14: Observations of equatorial spread F

Cited by 14 publications

References 38 publications

Longitudinal and Seasonal Variability of Equatorial Ionospheric Irregularities and Electrodynamics

Longitudinal and Seasonal Variability of Equatorial Ionospheric Irregularities and Electrodynamics

Concurrent observations at the magnetic equator of small‐scale irregularities and large‐scale depletions associated with equatorial spread F

Radio-frequency imaging techniques for ionospheric, magnetospheric, and planetary studies

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