West wall structuring of equatorial plasma bubbles simulated by three‐dimensional HIRB model

Yokoyama, T.; Jin, Hidekatsu; Shinagawa, Hiroyuki

doi:10.1002/2015ja021799

Cited by 27 publications

(22 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…That is, stronger GW activity may not always lead to more EPBs, at least for GWs in this study with horizontal scales below 620 km. This implication is in line with the works of Burke et al [2004], Kudeki et al [2007], and Yokoyama et al [2015], who found that instead of gravity waves, other factors like the magnetic declination, strong zonal winds, or vertical shear of zonal plasma drift can play more important roles in controlling EPB occurrence. Notably, the seasonal variation of the zonal wind in the evening sector fits perfectly to that of the EPB, with strongest wind around equinoxes, and weakest wind around June solstice [Liu et al, 2016].…”

Section: Discussionsupporting

confidence: 88%

“…Medium-scale gravity waves (GWs) with horizontal scales of a few hundred kilometers in the bottomside F region have been frequently suggested to play a key role in EPB seeding [e.g., Fritts et al, 2008;Abdu et al, 2009]. However, there are also a body of studies that argue against this hypothesis [e.g., Kudeki et al, 2007;Yokoyama et al, 2015]. The lack of direct measurements of gravity waves at this critical altitude undoubtedly contributes to this debate.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Medium‐scale gravity wave activity in the bottomside F region in tropical regions

Liu

Pedatella

Hocke

2017

Geophysical Research Letters

View full text Add to dashboard Cite

Thermospheric gravity waves (GWs) in the bottomside F region have been proposed to play a key role in the generation of equatorial plasma bubbles (EPBs). However, direct observations of such waves are scarce. This study provides a systematic survey of medium‐scale (<620 km) neutral atmosphere perturbations at this critical altitude in the tropics, using 4 years of in situ Gravity Field and Steady‐State Ocean Circulation Explorer satellite measurements of thermospheric density and zonal wind. The analysis reveals pronounced features on their global distribution and seasonal variability: (1) A prominent three‐peak longitudinal structure exists in all seasons, with stronger perturbations over continents than over oceans. (2) Their seasonal variation consists of a primary semiannual oscillations (SAO) and a secondary annual oscillation (AO). The SAO component maximizes around solstices and minimizes around equinoxes, while the AO component maximizes around June solstice. These GW features resemble those of EPBs in spatial distribution but show opposite trend in climatological variations. This may imply that stronger medium‐scale GW activity does not always lead to more EPBs. Possible origins of the bottomside GWs are discussed, among which tropical deep convection appears to be most plausible.

show abstract

Section: Discussionsupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Medium‐scale gravity wave activity in the bottomside F region in tropical regions

Liu

Pedatella

Hocke

2017

Geophysical Research Letters

View full text Add to dashboard Cite

show abstract

“…Applying multiple seeding components and an eastward neutral wind, east-west asymmetry, and tilted structures can also be reproduced, as shown in Fig. 8 (Yokoyama et al 2015). Although the outline of tilted EPBs is similar to the previous 2D model, result shown in Fig.…”

Section: Three-dimensional Modelssupporting

confidence: 50%

“…The most recent models developed by the author and colleagues could reproduce very turbulent structures inside EPBs (Yokoyama et al 2014(Yokoyama et al , 2015Yokoyama and Stolle 2017;Rino et al 2017). The purpose of this article is to review the development of numerical simulations of EPBs over the past 40 years and discuss a possible future research direction involving the use of state-of-the-art numerical models toward the evaluation and forecast of ionospheric scintillations.…”

Section: Introductionmentioning

confidence: 99%

A review on the numerical simulation of equatorial plasma bubbles toward scintillation evaluation and forecasting

Yokoyama

2017

Prog Earth Planet Sci

View full text Add to dashboard Cite

Equatorial plasma bubbles (EPBs) have been a longstanding and increasingly important subject because they cause severe scintillations in radio waves from Global Navigation Satellite System satellites. The phenomenon was found in the 1930s as irregular ionosonde observations and was termed equatorial spread F (ESF). ESF is interpreted as plasma density irregularities associated with EPBs that have nonlinearly evolved into the topside ionosphere. Numerical simulations have been powerful tools to study the fully nonlinear evolution of EPBs, which cannot be wholly understood from theoretical predictions. In this paper, historical achievements in the numerical simulation of EPBs are reviewed, and future directions toward scintillation evaluation and forecast are discussed.

show abstract

“…This explanation is appealing because there is a physical basis for this asymmetry. That is, west-wall structuring may be produced by an interchange instability, driven by an eastward neutral wind [Tsunoda, 1983], or structuring could be associated with a velocity shear in F region plasma [Yokoyama et al, 2015].…”

Section: East-west Asymmetriesmentioning

confidence: 99%

Off‐great‐circle paths in transequatorial propagation: 1. Discrete and diffuse types

et al. 2016

View full text Add to dashboard Cite

There is mounting evidence that plasma structure in nighttime equatorial F layer evolves from large‐scale wave structure (LSWS) in the bottomside F layer. This process cannot be ignored because equatorial plasma bubbles (EPBs) arise from large‐amplitude LSWS; and, because intense radiowave scintillations are associated with EPBs, understanding the LSWS‐to‐EPB process is a crucial step toward reliable Space Weather Forecasting. In this regard, the transequatorial propagation (TEP) experiment appears to be the most useful among available research instruments. After a lapse of 30 years, the TEP experiment has been resurrected; a goal of this research is to understand TEP measurements well enough so that they can be used to diagnose the LSWS‐to‐EPB process. Toward this end, new results are presented in two companion papers. Herein (P1), off‐great‐circle (OGC) propagation paths are shown to consist of two types, discrete and diffuse. The new findings include the following: (1) a generalized multireflection model that can explain most of the observed properties; (2) the discrete type is supported by multireflections from an unstructured upwelling, (3) the diffuse type is supported by reflections from plasma structure in EPBs; and (4) the observed east‐west (EW) asymmetry can be explained in terms of a distorted upwelling or plasma structure along the west wall of an upwelling. In Paper 2 (P2), a second form of observed EW asymmetry is explained in terms of plasma structure, which is not aligned with the geomagnetic field. The findings strongly confirm a close relationship between upwellings, ESF patches, and OGC paths.

show abstract

West wall structuring of equatorial plasma bubbles simulated by three‐dimensional HIRB model

Cited by 27 publications

References 37 publications

Medium‐scale gravity wave activity in the bottomside F region in tropical regions

Medium‐scale gravity wave activity in the bottomside F region in tropical regions

A review on the numerical simulation of equatorial plasma bubbles toward scintillation evaluation and forecasting

Off‐great‐circle paths in transequatorial propagation: 1. Discrete and diffuse types

Contact Info

Product

Resources

About