Statistics and Polarization of Type III Radio Bursts Observed in the Inner Heliosphere

Pulupa, M.; Bale, S. D.; Badman, S. T.; Bonnell, J. W.; Case, A. W.; Wit, T. Dudok de; Goetz, K.; Harvey, P.; Hegedus, Alexander M.; Kasper, J. C.; Korreck, K. E.; Krasnoselskikh, V.; Larson, D. E.; Lecacheux, A.; Livi, R.; MacDowall, R. J.; Maksimović, M.; Malaspina, D.; Oliveros, J. C. Martinez; Meyer‐Vernet, N.; Moncuquet, M.; Stevens, Michael L.; Whittlesey, P. L.

doi:10.3847/1538-4365/ab5dc0

Cited by 49 publications

(53 citation statements)

References 51 publications

(62 reference statements)

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“…1), it may lead to inaccuracies. For E2, in particular, the active region was responsible for observed solar impulsive events (Pulupa et al 2020). Fourth, MAS relies on a variety of approximations to reconstruct (or predict) the large-scale structure and properties of the solar corona and inner heliosphere.…”

Section: Modelsmentioning

confidence: 99%

Using Parker Solar Probe observations during the first four perihelia to constrain global magnetohydrodynamic models

Riley

Lionello

Caplan

et al. 2021

A&A

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Context. Parker Solar Probe (PSP) is providing an unprecedented view of the Sun’s corona as it progressively dips closer into the solar atmosphere with each solar encounter. Each set of observations provides a unique opportunity to test and constrain global models of the solar corona and inner heliosphere and, in turn, use the model results to provide a global context for interpreting such observations. Aims. In this study, we develop a set of global magnetohydrodynamic (MHD) model solutions of varying degrees of sophistication for PSP’s first four encounters and compare the results with in situ measurements from PSP, Stereo-A, and Earth-based spacecraft, with the objective of assessing which models perform better or worse. We also seek to understand whether the so-called ‘open flux problem’, which all global models suffer from, resolves itself at closer distances to the Sun. Methods. The global structure of the corona and inner heliosphere is calculated using three different MHD models. The first model (“polytropic”), replaced the energy equation as a simple polytropic relationship to compute coronal solutions and relied on an ad hoc method for estimating the boundary conditions necessary to drive the heliospheric model. The second model (“thermodynamic”) included a more sophisticated treatment of the energy equation to derive the coronal solution, yet it also relied on a semi-empirical approach to specify the boundary conditions of the heliospheric model. The third model (“WTD”) further refines the transport of energy through the corona, by implementing the so-called wave-turbulence-driven approximation. With this model, the heliospheric model was run directly with output from the coronal solutions. All models were primarily driven by the observed photospheric magnetic field using data from Solar Dynamics Observatory’s Helioseismic and Magnetic Imager instrument. Results. Overall, we find that there are substantial differences between the model results, both in terms of the large-scale structure of the inner heliosphere during these time periods, as well as in the inferred timeseries at various spacecraft. The “thermodynamic” model, which represents the “middle ground”, in terms of model complexity, appears to reproduce the observations most closely for all four encounters. Our results also contradict an earlier study that had hinted that the open flux problem may disappear nearer the Sun. Instead, our results suggest that this “missing” solar flux is still missing even at 26.9RS, and thus it cannot be explained by interplanetary processes. Finally, the model results were also used to provide a global context for interpreting the localized in situ measurements. Conclusions. Earlier studies suggested that the more empirically-based polytropic solutions provided the best matches with observations. The results presented here, however, suggest that the thermodynamic approach is now superior. We discuss possible reasons for why this may be the case, but, ultimately, more thorough comparisons and analyses are required. Nevertheless, it is reassuring that a more sophisticated model appears to be able to reproduce observations since it provides a more fundamental glimpse into the physical processes driving the structure we observe.

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Section: Modelsmentioning

confidence: 99%

Using Parker Solar Probe observations during the first four perihelia to constrain global magnetohydrodynamic models

Riley

Lionello

Caplan

et al. 2021

A&A

Self Cite

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“…The importance of far side evolution is particularly emphasized by PSP encounter 2 (middle column, figure 6), where step changes in metric scores are observed (around 2019-03-20 and 2019-04-08). For this specific encounter, there was significant solar activity (Pulupa et al 2020) which evolved and changed the global coronal field while out of view from Earth-based magnetograms, mostly concentrated in two key active regions (AR 12737 and AR12378, Harra et al 2021;Cattell et al 2021). This meant a strong photospheric field concentration rotated on disk twice during this time interval and at this time produced sudden and significant changes in magnetograms.…”

Section: Discussionmentioning

confidence: 94%

Constraining Global Coronal Models with Multiple Independent Observables

Badman,

Brooks,

Poirier

et al. 2022

Preprint

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Global coronal models seek to produce an accurate physical representation of the Sun's atmosphere which can be used, for example, to drive space weather models. Assessing their accuracy is a complex task and there are multiple observational pathways to provide constraints and tune model parameters. Here, we combine several such independent constraints, defining a model-agnostic framework for standardized comparison. We require models to predict the distribution of coronal holes at the photosphere, and neutral line topology at the model outer boundary. We compare these predictions to extreme ultraviolet (EUV) observations of coronal hole locations, white-light Carrington maps of the streamer belt and the magnetic sector structure measured in situ by Parker Solar Probe and 1AU spacecraft. We study these metrics for Potential Field Source Surface (PFSS) models as a function of source surface height and magnetogram choice, as well as comparing to the more physical Wang-Sheeley-Arge (WSA) and the Magnetohydrodynamics Algorithm outside a Sphere (MAS) models. We find that simultaneous optimization of PFSS models to all three metrics is not currently possible, implying a trade-off between the quality of representation of coronal holes and streamer belt topology. WSA and MAS results show the additional physics they include addresses this by flattening the streamer belt while maintaining coronal hole sizes, with MAS also improving coronal hole representation relative to WSA. We conclude that this framework is highly useful for inter-and intra-model comparisons. Integral to the framework is the standardization of observables required of each model, evaluating different model aspects.

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“…During a typical solar encounter, n avg is 80 and the RFS produces one LFR and one HFR averaged spectrum every 7 s. We will refer to this operating mode as "LFR/HFR mode." Details of the LFR/ HFR algorithms are described in Pulupa et al (2017), and examples of typical RFS performance in LFR/ HFR mode are described in Pulupa et al (2020).…”

Section: Rfs Burst Modementioning

confidence: 99%

Non‐Detection of Lightning During the Second Parker Solar Probe Venus Gravity Assist

Pulupa

Bale

Curry

et al. 2021

Geophysical Research Letters

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Lightning is an atmospheric electric discharge between two locations that have been charged to a large differential potential. In the terrestrial atmosphere, lightning occurs frequently (30-100 times per second worldwide) and produces a broad range of phenomena, including bright optical flashes and thunder (Dwyer & Uman, 2014). Lightning also generates electromagnetic whistlers, which can propagate into Earth's magnetosphere, and are detectable out to several Earth radii (Záhlava et al., 2019). At radio frequencies, lightning produces strong, transient broadband emissions commonly known as "sferics" (Smith et al., 2002). Terrestrial sferics typically exhibit a f −2 power spectrum at frequencies below a few MHz, steepening to f −4 at higher frequencies (Levine & Meneghini, 1978).While extraterrestrial lightning has been observed at Jupiter, Saturn, Uranus, and Neptune (Aplin et al., 2020), its existence at Venus remains an open question. Lorenz (2018) reviewed claims of detections and nondetections of lightning at Venus, concluding that while some type of electromagnetic activity is present (Russell et al., 2008), its properties are different from terrestrial lightning. During three years in orbit, Akatsuki did not detect optical emission due to lightning flashes (

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Statistics and Polarization of Type III Radio Bursts Observed in the Inner Heliosphere

Cited by 49 publications

References 51 publications

Using Parker Solar Probe observations during the first four perihelia to constrain global magnetohydrodynamic models

Using Parker Solar Probe observations during the first four perihelia to constrain global magnetohydrodynamic models

Constraining Global Coronal Models with Multiple Independent Observables

Non‐Detection of Lightning During the Second Parker Solar Probe Venus Gravity Assist

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