What if we had a magnetograph at Lagrangian L5?

Pevtsov, Alexei A.; Bertello, L.; MacNeice, P. J.; Petrie, Gordon

doi:10.1002/2016sw001471

Cited by 18 publications

(14 citation statements)

References 19 publications

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“…In the recent paper by Mackay et al (2016) it has been shown that such L5 observations could increase the accuracy of global quantities relevant to eruptions on the Sun by anywhere from 26-40%. Pevtsov et al (2016) reports similar improvements for the estimations of solar wind and plasma outflows as well. -Identification of erupting flux ropes.…”

Section: Producing An Operational Modelsupporting

confidence: 60%

A new technique for observationally derived boundary conditions for space weather

Pagano

Mackay

Yeates

2018

J. Space Weather Space Clim.

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-Context. In recent years, space weather research has focused on developing modelling techniques to predict the arrival time and properties of coronal mass ejections (CMEs) at the Earth. The aim of this paper is to propose a new modelling technique suitable for the next generation of Space Weather predictive tools that is both efficient and accurate. The aim of the new approach is to provide interplanetary space weather forecasting models with accurate time dependent boundary conditions of erupting magnetic flux ropes in the upper solar corona. Methods. To produce boundary conditions, we couple two different modelling techniques, MHD simulations and a quasi-static non-potential evolution model. Both are applied on a spatial domain that covers the entire solar surface, although they extend over a different radial distance. The non-potential model uses a time series of observed synoptic magnetograms to drive the non-potential quasi-static evolution of the coronal magnetic field. This allows us to follow the formation and loss of equilibrium of magnetic flux ropes. Following this a MHD simulation captures the dynamic evolution of the erupting flux rope, when it is ejected into interplanetary space. Results.The present paper focuses on the MHD simulations that follow the ejection of magnetic flux ropes to 4 R ⊙ . We first propose a technique for specifying the pre-eruptive plasma properties in the corona. Next, time dependent MHD simulations describe the ejection of two magnetic flux ropes, that produce time dependent boundary conditions for the magnetic field and plasma at 4 R ⊙ that in future may be applied to interplanetary space weather prediction models. Conclusions. In the present paper, we show that the dual use of quasi-static non-potential magnetic field simulations and full time dependent MHD simulations can produce realistic inhomogeneous boundary conditions for space weather forecasting tools. Before a fully operational model can be produced there are a number of technical and scientific challenges that still need to be addressed. Nevertheless, we illustrate that coupling quasi-static and MHD simulations in this way can significantly reduce the computational time required to produce realistic space weather boundary conditions.

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Section: Producing An Operational Modelsupporting

confidence: 60%

A new technique for observationally derived boundary conditions for space weather

Pagano

Mackay

Yeates

2018

J. Space Weather Space Clim.

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“…A continuous view of the solar poles is particularly compelling, both for space-weather monitoring and for establishing the nature of the solar dynamo. There are also mission concepts that would provide new insights while stopping short of full 4π coverage, such as an early-warning system at the Earth-Sun L5 point (e.g., Pevtsov et al 2016), or a two-spacecraft system that would improve upon STEREO's initial exploration of stereoscopic imaging (Strugarek et al 2015). Sustained multi-vantage observations of the photospheric magnetic field, the inner boundary of the heliosphere, has transformative potential.…”

Section: Observational Improvementsmentioning

confidence: 99%

Origins of the Ambient Solar Wind: Implications for Space Weather

2017

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The Sun's outer atmosphere is heated to temperatures of millions of degrees, and solar plasma flows out into interplanetary space at supersonic speeds. This paper reviews our current understanding of these interrelated problems: coronal heating and the acceleration of the ambient solar wind. We also discuss where the community stands in its ability to forecast how variations in the solar wind (i.e., fast and slow wind streams) impact the Earth. Although the last few decades have seen significant progress in observations and modeling, we still do not have a complete understanding of the relevant physical processes, nor do we have a quantitatively precise census of which coronal structures contribute to specific types of solar wind. Fast streams are known to be connected to the central regions of large coronal holes. Slow streams, however, appear to come from a wide range of sources, including streamers, pseudostreamers, coronal loops, active regions, and coronal hole boundaries. Complicating our understanding even more is the fact that processes such as turbulence, streamstream interactions, and Coulomb collisions can make it difficult to unambiguously map a parcel measured at 1 AU back down to its coronal source. We also review recent progress-in theoretical modeling, observational data analysis, and forecasting techniques that sit at the interface between data and theory-that gives us hope that the above problems are indeed solvable.

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“…Such comparisons are imperfect, and a one-to-one correspondence between EUV-dark regions in the images and open-flux domains from the model is not expected (see Lowder et al 2014Lowder et al , 2017. Several reasons probably account for these discrepancies: (1) Pevtsov et al 2016). Structures in the eastern hemisphere may be ad-versely affected when there is a significant amount of flux at or past the east limb that has not yet been assimilated into the surface-flux model that comprises the lower-boundary condition of the PFSS extrapolation.…”

Section: Comparisons With Coronal Holesmentioning

confidence: 99%

Does Nearby Open Flux Affect the Eruptivity of Solar Active Regions?

DeRosa

Barnes

2018

ApJ

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The most energetic solar flares are typically associated with the ejection of a cloud of coronal material into the heliosphere in the form of a coronal mass ejection (CME). However, there exist large flares which are not accompanied by a CME. The existence of these non-eruptive flares raises the question of whether such flares suffer from a lack of access to nearby open fields in the vicinity above the flare (reconnection) site. In this study, we use a sample of 56 flares from Sunspot Cycles 23 and 24 to test whether active regions that produce eruptive X-class flares are preferentially located near coronal magnetic field domains that are open to the heliosphere, as inferred from a potential field source surface model. The study shows that X-class flares having access to open fields are eruptive at a higher rate than those for which access is lacking. The significance of this result should be moderated due to the small number of non-eruptive X-class flares in the sample, based on the associated Bayes factor.

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What if we had a magnetograph at Lagrangian L5?

Cited by 18 publications

References 19 publications

A new technique for observationally derived boundary conditions for space weather

A new technique for observationally derived boundary conditions for space weather

Origins of the Ambient Solar Wind: Implications for Space Weather

Does Nearby Open Flux Affect the Eruptivity of Solar Active Regions?

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