Electrodynamics of midlatitude spread <i>F</i>: 1. Observations of unstable, gravity wave‐induced ionospheric electric fields at tropical latitudes

Miller, Clark A.; Swartz, Wesley E.; Kelley, M. C.; Mendillo, M.; Nottingham, D.; Scali, J. L.; Reinisch, B. W.

doi:10.1029/96ja03839

Cited by 128 publications

(120 citation statements)

References 39 publications

Supporting

Mentioning

109

Contrasting

Unclassified

Order By: Relevance

“…The effects observed included a remarkable spectrum of airglow depletions; some were interpreted as signatures of traveling ionospheric disturbances (TIDs) and others as ESF effects found to be at extraordinary distances from the geomagnetic equator (Mendillo et al, 1997b). In follow up work (Miller et al, 1997;Kelley et al, 2002), the TIDs were hypothesized to be a form of the Perkins instability (Perkins, 1973); the possibility of ESF effects reaching Arecibo's location at L∼1.3 remained surprising and controversial . An ASC in the Southern Hemisphere (at a longitude comparable to Arecibo's) offers a way to test if processes ordered by geomagnetic fluxtube geometries (such as ESF) were seen in conjugate regions.…”

Section: Introductionmentioning

confidence: 99%

“…Two observing campaigns (in 1993 and 1995) revealed a robust set of airglow structures (Mendillo et al, 1997b;Miller et al, 1997) that brought new groups into the optical community and generated considerable interest in dynamical processes at the interface between the equatorial aeronomy domain and midlatitudes. The effects observed included a remarkable spectrum of airglow depletions; some were interpreted as signatures of traveling ionospheric disturbances (TIDs) and others as ESF effects found to be at extraordinary distances from the geomagnetic equator (Mendillo et al, 1997b).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Imaging science at El Leoncito, Argentina

Martinis¹,

Baumgardner²,

Smith³

et al. 2006

Ann. Geophys.

Self Cite

View full text Add to dashboard Cite

Abstract. Thermospheric and mesospheric structures are studied using an all-sky imager located at El Leoncito, Argentina (31.8 • S, 69.3 • W, -18 • mag lat). This site has relatively high geographic latitude for a location under the crest of the equatorial ionization anomaly (EIA), and thus observations can be used to study the intrusion of several equatorial processes into the midlatitude domain. In addition, it has a conjugate point close to the field of view of our companion imager at Arecibo, PR, allowing for the study of interhemispheric effects. Four types of phenomena were studied using 630.0 nm and 777.4 nm observations: (1) highlystructured airglow depletions associated with the RayleighTaylor instability/equatorial spread-F (RTI/ESF) process, (2) brightness waves (BW) associated with the midnight temperature maximum (MTM), (3) strong airglow enhancements associated with the positive phase of ionospheric storms, and (4) simple (non-structured) bands of airglow depletions with characteristics matching a Perkins-like instability. Using 557.7 nm mesospheric observations, a fifth category of study deals with gravity waves probably generated by lower atmospheric disturbances, and mesospheric bores related to strong vertical temperature gradients.While ESF depletions and BW events are detected fairly frequently, the mid-latitude bands are not, and thus their successful imaging at El Leoncito offers the first example of the coupling from mid-latitudes to low-latitudes in the South American longitude sector. Preliminary results on these features are presented in this paper. Taken together, these five types of optical structures offer the opportunity to investigate coupling, both in altitude and latitude, of aeronomic processes at low latitudes in an under-sampled longitude sector in the Southern Hemisphere.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Imaging science at El Leoncito, Argentina

Martinis¹,

Baumgardner²,

Smith³

et al. 2006

Ann. Geophys.

Self Cite

View full text Add to dashboard Cite

show abstract

“…Nighttime traveling ionospheric disturbances (TIDs) at mid-latitudes have been observed in several longitudinal sectors and with several observational techniques in recent years (Jacobson et al, 1995;Miller et al, 1997;Garcia et al, 2000). Interest has grown because their features cannot be explained by the classical theory proposed by Hines (1964) Saito et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

Observations of traveling ionospheric disturbances and 3-m scale irregularities in the nighttime F-region ionosphere with the MU radar and a GPS network

et al. 2014

Self Cite

View full text Add to dashboard Cite

The nighttime traveling ionospheric disturbances (TIDs) and the F-region 3-m scale field-aligned irregularities were simultaneously observed with the MU radar and GEONET, a GPS network, during the FRONT (F-region Radio and Optical measurement of the Nighttime TID) campaign periods in May 1998 and August 1999. The vertical profile of electron density detected by the incoherent scatter observation of the MU radar clarified that ionized atmosphere on the bottomside of the ionospheric F-region was deeply modulated by TIDs, which would cause the variations of the 630 nm band airglow luminosity. The coherent echoes from the 3-m scale fieldaligned irregularities were detected also on the bottomside of the F-region in the nights when TIDs were intense in amplitude and the ionosphere was uplifted. Two-dimensional structures of the field-aligned irregularities detected by the multi-beam observation of the MU radar revealed that the 3-m scale irregularities formed band-like structures and traveled to the southwest in several nights. Their wave vector and traveling velocity were coincident with those of the nighttime TIDs that were simultaneously detected by the TEC observation of GEONET. The intense Doppler velocities of the coherent echoes indicate that the polarization electric field is generated inside the TIDs. We consider that the horizontal gradient of the electric conductivity associated by TIDs and the vertical gradient of the conductivity on the bottomside of the F-region ionosphere generates the 3-m scale irregularities through the gradient-drift instability process. The anti-correlation of the occurrence rate of the F-region field-aligned irregularities to the solar activity would be caused by the anti-correlation of the amplitude of TIDs and of the vertical gradient of the Pedersen conductivity.

show abstract

“…This agrees with the statistical preference for NW-SE offsets seen in our MWA data. It is speculated that an electrodynamic instability known as the Perkins instability (Perkins 1973;Miller et al 1997;Hamza 1999;Yokoyama et al 2009) may account for the formation of structures elongated preferentially along a certain direction. Under this mechanism, vertical undulations (e.g.…”

Section: Interpreting Position Offsetsmentioning

confidence: 99%

Quantifying ionospheric effects on time-domain astrophysics with the Murchison Widefield Array

Loi

Murphy

Bell

et al. 2015

Mon. Not. R. Astron. Soc.

View full text Add to dashboard Cite

Refraction and diffraction of incoming radio waves by the ionosphere induce time variability in the angular positions, peak amplitudes and shapes of radio sources, potentially complicating the automated cross-matching and identification of transient and variable radio sources. In this work, we empirically assess the effects of the ionosphere on data taken by the Murchison Widefield Array (MWA) radio telescope. We directly examine 51 hours of data observed over 10 nights under quiet geomagnetic conditions (global storm index K p < 2), analysing the behaviour of short-timescale angular position and peak flux density variations of around ten thousand unresolved sources. We find that while much of the variation in angular position can be attributed to ionospheric refraction, the characteristic displacements (10-20 arcsec) at 154 MHz are small enough that search radii of 1-2 arcmin should be sufficient for cross-matching under typical conditions. By examining bulk trends in amplitude variability, we place upper limits on the modulation index associated with ionospheric scintillation of 1-3% for the various nights. For sources fainter than ∼1 Jy, this variation is below the image noise at typical MWA sensitivities. Our results demonstrate that the ionosphere is not a significant impediment to the goals of time-domain science with the MWA at 154 MHz.

show abstract

Electrodynamics of midlatitude spread F: 1. Observations of unstable, gravity wave‐induced ionospheric electric fields at tropical latitudes

Cited by 128 publications

References 39 publications

Imaging science at El Leoncito, Argentina

Imaging science at El Leoncito, Argentina

Observations of traveling ionospheric disturbances and 3-m scale irregularities in the nighttime F-region ionosphere with the MU radar and a GPS network

Quantifying ionospheric effects on time-domain astrophysics with the Murchison Widefield Array

Contact Info

Product

Resources

About