Origins of the Ambient Solar Wind: Implications for Space Weather

Cranmer, Steven R.; Gibson, S. E.; Riley, Pete

doi:10.1007/s11214-017-0416-y

Cited by 137 publications

(125 citation statements)

References 365 publications

(338 reference statements)

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“…The open flux of the wind, Φ open , is relevant as regions of open flux the origin of the fast solar/stellar wind (Verdini et al 2010;Réville et al 2016;Cranmer et al 2017). It is also related to how efficient the wind is at transporting angular momentum from the star (Réville et al 2015).…”

Section: Mass-loss Rates (ṁ) Angular Momentum-loss Rates (J) and Open mentioning

confidence: 99%

The Solar Wind in Time II: 3D stellar wind structure and radio emission

Fionnagáin

Vidotto

Petit

et al. 2018

Monthly Notices of the Royal Astronomical Society

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In this work, we simulate the evolution of the solar wind along its main sequence lifetime and compute its thermal radio emission. To study the evolution of the solar wind, we use a sample of solar mass stars at different ages. All these stars have observationally-reconstructed magnetic maps, which are incorporated in our 3D magnetohydrodynamic simulations of their winds. We show that angular-momentum loss and mass-loss rates decrease steadily on evolutionary timescales, although they can vary in a magnetic cycle timescale. Stellar winds are known to emit radiation in the form of thermal bremsstrahlung in the radio spectrum. To calculate the expected radio fluxes from these winds, we solve the radiative transfer equation numerically from first principles. We compute continuum spectra across the frequency range 100 MHz -100 GHz and find maximum radio flux densities ranging from 0.05 -8.3 µJy. At a frequency of 1 GHz and a normalised distance of d = 10 pc, the radio flux density follows 0.24 (Ω/Ω ) 0.9 (d/[10pc]) 2 µJy, where Ω is the rotation rate. This means that the best candidates for stellar wind observations in the radio regime are faster rotators within distances of 10 pc, such as κ 1 Ceti (2.83 µJy) and χ 1 Ori (8.3 µJy). These flux predictions provide a guide to observing solar-type stars across the frequency range 0.1 -100 GHz in the future using the next generation of radio telescopes, such as ngVLA and SKA.

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Section: Mass-loss Rates (ṁ) Angular Momentum-loss Rates (J) and Open mentioning

confidence: 99%

The Solar Wind in Time II: 3D stellar wind structure and radio emission

Fionnagáin

Vidotto

Petit

et al. 2018

Monthly Notices of the Royal Astronomical Society

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“…Wang and Sheeley, 1990;Luhmann et al, 2009;Petrie and Haislmaier, 2013). In that respect, also polar coronal holes influence the solar wind speed in the ecliptic plane, however, the interplay between polar and low lying coronal holes is not fully understood yet (see also a recent review by Cranmer et al, 2017). Miyake (2012) concluded from investigating STEREO in situ data during 2007-2009 for predicting the Kp-index, that a simple correlation method of solar wind measurement at separated solar longitude is not enough even though the correlation is generally high.…”

Section: Summary and Discussionmentioning

confidence: 99%

Coronal hole evolution from multi-viewpoint data as input for a STEREO solar wind speed persistence model

Temmer

Hinterreiter

Reiss

2018

J. Space Weather Space Clim.

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-We present a concept study of a solar wind forecasting method for Earth, based on persistence modeling from STEREO in situ measurements combined with multi-viewpoint EUVobservational data. By comparing the fractional areas of coronal holes (CHs) extracted from EUV data of STEREO and SoHO/ SDO, we perform an uncertainty assessment derived from changes in the CHs and apply those changes to the predicted solar wind speed profile at 1 AU. We evaluate the method for the time period [2008][2009][2010][2011][2012], and compare the results to a persistence model based on ACE in situ measurements and to the STEREO persistence model without implementing the information on CH evolution. Compared to an ACE based persistence model, the performance of the STEREO persistence model which takes into account the evolution of CHs, is able to increase the number of correctly predicted high-speed streams by about 12%, and to decrease the number of missed streams by about 23%, and the number of false alarms by about 19%. However, the added information on CH evolution is not able to deliver more accurate speed values for the forecast than using the STEREO persistence model without CH information which performs better than an ACE based persistence model. Investigating the CH evolution between STEREO and Earth view for varying separation angles over ∼25-140°East of Earth, we derive some relation between expanding CHs and increasing solar wind speed, but a less clear relation for decaying CHs and decreasing solar wind speed. This fact most likely prevents the method from making more precise forecasts. The obtained results support a future L5 mission and show the importance and valuable contribution using multi-viewpoint data.

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“…The different types of perturbations (X-ray flares, SEPs, CMEs, coronal holes) find their correspondence in rather separated modeling communities (Zhao & Dryer, 2014;Luhmann et al, 2015;Barnes et al, 2016;Reiss et al, 2016;Cranmer et al, 2017;Murray et al, 2017). Further splitting of modeling activity occurs for regions closer to Earth (magnetosphere, ionosphere/thermosphere, Earth atmosphere and surface) because of traditional scientific domains, specific customer needs, as well as the physical processes involved (Lathuillère et al, 2002).…”

Section: Modeling Aspectsmentioning

confidence: 99%

Climate, weather, space weather: model development in an operational context

Folini

2018

J. Space Weather Space Clim.

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-Aspects of operational modeling for climate, weather, and space weather forecasts are contrasted, with a particular focus on the somewhat conflicting demands of "operational stability" versus "dynamic development" of the involved models. Some common key elements are identified, indicating potential for fruitful exchange across communities. Operational model development is compelling, driven by factors that broadly fall into four categories: model skill, basic physics, advances in computer architecture, and new aspects to be covered, from costumer needs over physics to observational data. Evaluation of model skill as part of the operational chain goes beyond an automated skill score. Permanent interaction between "pure research" and "operational forecast" people is beneficial to both sides. This includes joint model development projects, although ultimate responsibility for the operational code remains with the forecast provider. The pace of model development reflects operational lead times. The points are illustrated with selected examples, many of which reflect the author's background and personal contacts, notably with the Swiss Weather Service and the Max Planck Institute for Meteorology, Hamburg, Germany. In view of current and future challenges, large collaborations covering a range of expertise are a must À within and across climate, weather, and space weather. To profit from and cope with the rapid progress of computer architectures, supercompute centers must form part of the team.

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Origins of the Ambient Solar Wind: Implications for Space Weather

Cited by 137 publications

References 365 publications

The Solar Wind in Time II: 3D stellar wind structure and radio emission

The Solar Wind in Time II: 3D stellar wind structure and radio emission

Coronal hole evolution from multi-viewpoint data as input for a STEREO solar wind speed persistence model

Climate, weather, space weather: model development in an operational context

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