A midday bite-out event of the F2-layer observed by MU radar.

Saryo, T.; Takeda, Masahiko; Araki, Tohru; Sato, Toru; Tsuda, Toshitaka; Fukao, S.; Katō, Susumu

doi:10.5636/jgg.41.727

Cited by 23 publications

(23 citation statements)

References 8 publications

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“…This result is similar to those reported by Khan et al (1985) and Saryo et al (1989). In fact both Khan et al (1985) and Saryo et al (1989) attributed the bite-outs they observed to poleward/equatorward neutral winds after ruling out vertical E × B drifts due to the fact that the observing stations were outside of the equatorial anomaly region and the structures were propagating equatorward and thus cannot be originating from enhancement of the equatorial eastward/westward electric field. Both studies reached the conclusion that poleward/equatorward Figure 6.…”

Section: Discussionsupporting

confidence: 80%

“…The time difference between a decrease in hmF2 and a decrease in NmF2 of the bite-out structures observed over HE13N, MU12K and PQ052 ranges from 45 min to 1.75 h, 45 min to 1.50 h and 1.25 to 2.25 h respectively. These delays are slightly longer than those reported by Saryo et al (1989), who found a time delay of about 30 min between the decrease of hmF2 and foF2 bite-outs in their study. The decrease of hmF2 prior to NmF2 bite-outs seems to indicate that the descent of hmF2 to altitudes where the dissociative recombination rate of oxygen ion is higher results in plasma depletions observed as biteout structures.…”

Section: Resultscontrasting

confidence: 53%

“…Also since the geomagnetic conditions are quiet, the EIA is not expected to extend to middle-latitude regions. Therefore we deduce that like Khan et al (1985) and Saryo et al (1989) the daytime twin-peak structures reported here have no direct link to the EIA. From the ionosonde data we observed that the hmF2 descends to lower altitudes prior to NmF2 depletions and that prior to that the vertical drift of the equivalent wind is downward.…”

Section: Discussionmentioning

confidence: 61%

“…poleward) were abundant in summer. Saryo et al (1989) reported first observation of a midday bite-out event over Japan on 12 November 1985 from electron density profiles obtained from MU (Middle and Upper atmosphere) radar and several ionosonde stations. Their biteout event was moving from higher-to lower-latitude stations (i.e.…”

Section: Introductionmentioning

confidence: 99%

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Daytime twin-peak structures observed at southern African and European middle latitudes on 8–13 April 2012

2016

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Abstract. Daytime twin-peak structures, also known as biteout or diurnal double-maxima structures, are ionospheric phenomena in which the diurnal ionospheric trend shows two peaks (instead of the normal one) during the daytime. This study reports on first simultaneous observations of these structures in the Global Positioning System and ionosonde measurements from the southern African and European middle-latitude stations during a mostly quiet geomagnetic condition period of 8-13 April 2012, which indicates that their occurrence and therefore driving mechanism(s) may not be localised. It is found that the daytime twin-peak structures generally appear later in the Northern Hemisphere with a 1-3 h latency although they propagate mostly equatorward in both hemispheres. Proxies of meridional neutral winds were calculated from available manually scaled ionosonde measurements and used to explore their potential as drivers of the structures. Bite-out events were linked to downward drifts of the vertical component of equivalent neutral winds causing plasma depletions. In addition, evidence of sporadic E layers at the same time as enhancements of daytime twin-peak structures suggests that the tides had influence via the meridional wind shear in generating these structures through the dynamo electric field which resulted in upward E × B drifts.

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Section: Discussionsupporting

confidence: 80%

Section: Resultscontrasting

confidence: 53%

Section: Discussionmentioning

confidence: 61%

Section: Introductionmentioning

confidence: 99%

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Daytime twin-peak structures observed at southern African and European middle latitudes on 8–13 April 2012

2016

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“…3, which is different from Fig. 14 in Nakanishi et al (2014). This characteristic may have come from the phenomenon called "Midday Bite-Out event of the F2-layer" where the electron density is anomalously depressed at middle and low latitudes in the daytime due to a poleward neutral wind (Saryo et al 1989). We note that the LT variation of the meridional component of average MR amplitude shows a similar "bite out" around noon.…”

Section: Confirmation Of Previous Climatological Resultsmentioning

confidence: 75%

Magnetic ripples observed by Swarm satellites and their enhancement during typhoon activity

Aoyama

Iwamoto

Nakanishi

2017

Earth Planets Space

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The Swarm satellites observed small-amplitude (0.1-5 nT) magnetic fluctuations perpendicular to the geomagnetic field. These so-called magnetic ripples (MRs) have a period of around a few tens of seconds along the satellite orbit in the topside ionosphere at middle and low latitudes. They are spatial structures from small-scale field-aligned currents. We investigated the following three characteristics of the MRs. First, we used Swarm observations to confirm their basic characteristics obtained from the Challenging Minisatellite Payload satellite. That is, the global distribution of the average MR amplitudes has clear geographic, seasonal, and local time dependence that is highly correlated with ionospheric conductivities. Second, we found that the average amplitudes of the MRs derived from the Swarm-B satellite, which flies at a ~50 km higher altitude, are slightly smaller than those of the Swarm-A and Swarm-C. This difference suggests that the location of the origin of MRs is below ~460 km altitude, i.e., not in the magnetosphere. Last, to provide evidence of correlation between the MRs and meteorological phenomena, we performed statistical and event analyses with typhoon track data, which are a source of acoustic and gravity waves. The data from 54 typhoons during the period from November 26, 2013, to July 31, 2016, were used for statistical analysis. The results show that the average amplitudes of the MRs during typhoon activity on the dawn, dusk, and night sides are larger than those during non-typhoon conditions. Event analyses indicate amplitude enhancements of the MRs around typhoons, and the latitude of the enhancement migrated with the typhoon. These analyses indicate that typhoon activity is correlated with MR activity and that cumulus convection activity other than typhoons may also affect MR amplitudes.

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The spatial and temporal structure of twin peaks and midday bite out in f_oF₂ (with associated height changes) in the Australian and South Pacific low midlatitude ionosphere

Lynn¹,

Gardiner-Garden

Heitmann

2014

JGR Space Physics

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A midday bite-out event of the F2-layer observed by MU radar.

Abstract: except the northernmost station, Wakkanai, and most prominently at Kokubunji. It occurred slightly earlier at higher latitudes. These facts suggest that the event was caused by poleward neutral winds.

Cited by 23 publications

References 8 publications

Daytime twin-peak structures observed at southern African and European middle latitudes on 8–13 April 2012

Daytime twin-peak structures observed at southern African and European middle latitudes on 8–13 April 2012

Magnetic ripples observed by Swarm satellites and their enhancement during typhoon activity

The spatial and temporal structure of twin peaks and midday bite out in f_oF₂ (with associated height changes) in the Australian and South Pacific low midlatitude ionosphere

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A midday bite-out event of the F2-layer observed by MU radar.

Abstract: except the northernmost station, Wakkanai, and most prominently at Kokubunji. It occurred slightly earlier at higher latitudes. These facts suggest that the event was caused by poleward neutral winds.

Cited by 23 publications

References 8 publications

Daytime twin-peak structures observed at southern African and European middle latitudes on 8–13 April 2012

Daytime twin-peak structures observed at southern African and European middle latitudes on 8–13 April 2012

Magnetic ripples observed by Swarm satellites and their enhancement during typhoon activity

The spatial and temporal structure of twin peaks and midday bite out in foF2 (with associated height changes) in the Australian and South Pacific low midlatitude ionosphere

Contact Info

Product

Resources

About

The spatial and temporal structure of twin peaks and midday bite out in f_oF₂ (with associated height changes) in the Australian and South Pacific low midlatitude ionosphere