Simulated Dynamic Spectra: A Group of Coronal Type III Bursts

Li, Bo

doi:10.1086/521723

Cited by 10 publications

(19 citation statements)

References 20 publications

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“…Result 1, however, does not exclude the possible existence of fundamental‐harmonic pairs at the low‐frequency ends of metric type III bursts, although 2 f p emission dominates. Moreover, Results 1 and 6, together with our recent work [ Li , 2007] indicate that an interplanetary type III burst may result from merging of a group of coronal type III bursts in the upper coronal or in the solar wind, and both f p and 2 f p emissions may be important for interplanetary type III bursts.…”

Section: Discussionsupporting

confidence: 61%

“…Our initial results [cf. Li , 2007], for instance, show that the merging of three identical beams lead to ∼12 times as much 2 f p flux at ∼130 MHz as a single beam alone, owing to these nonlinear effects.…”

Section: Discussionmentioning

confidence: 99%

“…The speed dependence of f h and f c is assumed to be Maxwellian, following previous simulations [e.g., Grognard , 1985]. On the basis of observations [ Aschwanden et al , 1995; Aschwanden , 2002; Klein et al , 2005] the following beam acceleration parameters were chosen in paper 2: T h = 25 MK, x 0 = 104 Mm, δx = 3 Mm, t 0 = 5 × 10 −2 s, and δ t = 10 −2 s. The parameter F acc was set to be 5 × 10 −6 , similar to Li [2007].…”

Section: Overview Of the Simulation Model The Nominal Simulation Anmentioning

confidence: 99%

“…Value chosen similar toLi et al [2006] andLi [2007].d Value chosen for the size of the 1-D simulation box in Figure 1. e Value chosen similar to Willes et al [1996] and Li et al [2006]. f Value chosen on the basis of…”

mentioning

confidence: 99%

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Simulations of coronal type III solar radio bursts: 3. Effects of beam and coronal parameters

Cairns

Robinson

2009

J. Geophys. Res.

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[1] A recently developed simulation model is used to investigate the effects of varying the coronal and electron heating conditions on the dynamic spectra of coronal type III bursts (70-370 MHz) observed at Earth. The flux of 2f p emission is significantly higher than that of f p emission, which is unlikely to be observable except under very favorable propagation conditions. Moreover, the 2f p emission is unlikely to continue into the solar wind, although some bursts are very strong and will extend into the upper corona with lower frequencies than simulated, consistent qualitatively with observations. The flux and brightness temperature of 2f p emission are affected significantly by variations in the parameters, while the frequency drift rate and half-power duration are affected only weakly. Further, the simulations confirm the standard interpretation of the drift rate of 2f p emission in terms of the plasma density profile and a characteristic beam speed that agrees quantitatively with the simulated beam dynamics for wide ranges of coronal and heating conditions. For weak heating events or events with high coronal electron temperature, the remote radiation shows characteristics that agree quantitatively with microbursts. When the heating is even weaker and/or the electron temperature is even higher, the heating events are radio quiet, consistent qualitatively with hard X-ray observations. For similar heating originating in similar frequency ranges, different density models yield quantitatively similar results except for the drift rate. Variations of the levels of a given density profile, corresponding to background corona or coronal streamers, can also cause significant changes in spectral characteristics.

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Section: Discussionsupporting

confidence: 61%

Section: Discussionmentioning

confidence: 99%

Section: Overview Of the Simulation Model The Nominal Simulation Anmentioning

confidence: 99%

mentioning

confidence: 99%

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Simulations of coronal type III solar radio bursts: 3. Effects of beam and coronal parameters

Cairns

Robinson

2009

J. Geophys. Res.

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“…, similar to that of Li [2007]. For the arc-shaped ES angular spectra described by equation (A8) in paper 1, we choose b = 20 that corresponds to a characteristic angular spread of 18°, following our previous work [Li et al, 2006b].…”

Section: à6mentioning

confidence: 99%

Simulations of coronal type III solar radio bursts: 2. Dynamic spectrum for typical parameters

Cairns

Robinson

2008

J. Geophys. Res.

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[1] Predictions are presented for the dynamic spectrum of a coronal type III burst observed at Earth, using a newly developed simulation model and employing realistic electron release and coronal parameters. The spectrum is studied in detail in association with the dynamics of beam and waves in the source. The frequency drift rate, radio flux, brightness temperature, and temporal profile of the type III burst agree semiquantitatively with typical observations. The simulation model is thus viable. Because of strong freefree absorption and scattering-induced damping, the flux of f p emission is significantly lower than that of 2f p emission and is below the lower thresholds of typical radio instruments. Moreover, the f p emission terminates at frequencies higher than the minimum simulated, and the 2f p emission appears to terminate at higher coronal altitudes that are not simulated because of computational limitations. Further simulations indicate that F-H pairs may exist under favorable conditions (e.g., generally, lower levels and larger length scales of the density fluctuations).Citation: Li, B., I. H. Cairns, and P. A. Robinson (2008), Simulations of coronal type III solar radio bursts: 2. Dynamic spectrum for typical parameters,

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Solar and Interplanetary Radio Emissions

Maia²,

Maksimović

2010

The Sun, the Solar Wind, and the Heliosphere

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Simulated Dynamic Spectra: A Group of Coronal Type III Bursts

Cited by 10 publications

References 20 publications

Simulations of coronal type III solar radio bursts: 3. Effects of beam and coronal parameters

Simulations of coronal type III solar radio bursts: 3. Effects of beam and coronal parameters

Simulations of coronal type III solar radio bursts: 2. Dynamic spectrum for typical parameters

Solar and Interplanetary Radio Emissions

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