Nonlinear Alfven Wave Propagation in the Solar Wind

Lau, Yun-Tung; Siregar, E.

doi:10.1086/177432

Cited by 27 publications

(18 citation statements)

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“…This has long been of interest in wave models of solar coronal heating and dynamics, because reflections tend to limit the amount of energy reaching the corona and solar wind [e.g., An et al, , 1990Barkhudarov, 1991;Bogdan et al, 2003;Charbonneau and MacGregor, 1995;Ferraro and Plumpton, 1958;Grappin et al, 2000Grappin et al, , 2002Hollweg, 1981Hollweg, , 1991Krogulec and Musielak, 1998;Krogulec et al, 1994;Lau and Siregar, 1996;Leroy, 1980;Lou and Rosner, 1994;Moore et al, 1991aMoore et al, , 1991bOfman and Davila, 1995;Orlando et al, 1996Orlando et al, , 1997Rosner et al, 1991;Stark, 1996;Suzuki and Inutsuka, 2005;Turkmani and Torkelsson, 2004;Velli et al, 1991;Velli, 1993;Ventura et al, 1999]. Reflections may also lead to interesting dynamic effects, such as shock formation and spicules [Hollweg, 1982;de Pontieu et al, 2004] (see also the review by Sterling [2000]).…”

Section: Introductionmentioning

confidence: 99%

Reflection of Alfvén waves in the corona and solar wind: An impulse function approach

Hollweg

Isenberg

2007

J. Geophys. Res.

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[1] We consider the reflection of Alfvén waves in the corona and solar wind, using variables f and g which follow sunward and antisunward characteristics, respectively. We show that the basic equations for f and g have the same structure as the Klein-Gordon equation. Unlike previous studies which used a harmonic analysis, we emphasize the impulse response of the system. This is equivalent to finding the Green's function, but it may have direct application to situations where Alfvén waves are launched impulsively. We provide an approximate analysis which can be used to understand most features that appear in detailed numerical solutions. The analysis reveals the origin of a previous result that f and g each has both sunward and antisunward propagating phase in a harmonic analysis, even though f (g) follows only the sunward (antisunward) characteristic. We numerically study the propagation of an antisunward moving impulse in the corona and solar wind. We find that the sunward moving ''wake'' tends to become more important at greater distances beyond the Alfvén critical point, possibly providing a natural explanation of the observation that outward propagating waves become less dominant at greater distances from the Sun. There is an extended region behind the initial impulse in which magnetic energy dominates kinetic energy; it is not clear, however, whether our result can explain the observed dominance of magnetic energy throughout many decades of frequency in the observed power spectrum. We also find that the outgoing wake has a tendency to ''ring,'' with periods of the order of 15-30 min. The ringing is associated mainly with propagation through a structured Alfvén speed profile rather that with the cutoff in the Klein-Gordon equation. These oscillation periods seem too short to explain why Alfvén waves in the solar wind have most power at periods of hours, but other Alfvén speed profiles could yield longer periods. We also investigate whether the same approach can be used for acoustic-gravity waves propagating along magnetic flux tubes in the solar atmosphere.

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Section: Introductionmentioning

confidence: 99%

Reflection of Alfvén waves in the corona and solar wind: An impulse function approach

Hollweg

Isenberg

2007

J. Geophys. Res.

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“…The propagation of Alfvén waves in the solar wind has been extensively studied by many authors through numerical simulations in association with the coronal heating and wind acceleration [ Ofman , 2004; Ofman and Davila , 1998; Lau and Siregar , 1996; Buti et al , 1998; Buti et al , 1999]. Suzuki and Inutsuka [2006] performed an MHD simulation from the photosphere toward the solar wind, and concluded that low‐frequency Alfvén waves can establish both the coronal high temperature and the high‐speed solar wind.…”

Section: Introductionmentioning

confidence: 99%

Parametric decay of circularly polarized Alfvén waves in the radially expanding solar wind

2007

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[1] We present a magnetohydrodynamic (MHD) simulation study of the parametric decay of the circularly polarized Alfvén waves propagating in the radial outflow of the solar wind. Assuming the transonic wind solution as an initial condition, we continuously injected monochromatic circularly polarized Alfvén waves from the inner boundary at the lower corona, and simulated the wave propagation. The injected Alfvén waves are subject to the parametric decay, and density fluctuations in the solar wind plasma grow rapidly at a specific region. The location of the most unstable region depends on the amplitude and frequency of injected Alfvén waves. We found that the unstable region of simulation results can be well estimated by considering a localized dispersion relation in the frame of reference moving with the background solar wind.Citation: Tanaka, S., T. Ogino, and T. Umeda (2007), Parametric decay of circularly polarized Alfvén waves in the radially expanding solar wind,

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“…The amount of energy carried by transverse tube waves has been added ad hoc in these models (see Ulmschneider et al 2001a). Similarly, the amount of energy carried by transverse waves at the Send offprint requests to: P. Ulmschneider, e-mail: ulmschneider@ita.uni-heidelberg.de wind base has also been assumed in our wind models (see also MacGregor & Charbonneau 1994;Lau & Siregar 1996;and Ofman & Davila 1998). Clearly, detailed calculations of the efficiency of the generation of transverse tube waves in stellar convection zones are required and this is the main goal of the present paper.…”

Section: Introductionmentioning

confidence: 99%

Excitation of transverse magnetic tube waves in stellar convection zones

Musielak

Ulmschneider

2002

A&A

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Abstract. The wave energy spectra and fluxes for transverse magnetic tube waves generated in stellar convection zones are computed by using the analytical method developed in the previous paper of this series. The main physical process responsible for the generation of these waves is shaking of a thin and vertically oriented magnetic flux tube by the external turbulent convection. The approach includes the correlation effects, which occur when the tube is shaken over a significant fraction of its length, but is limited to linear waves. The calculations are performed for population I stars with effective temperatures ranging from T eff = 2000 K to 10 000 K, and with gravities log g = 3-5. It is shown that the fluxes carried by linear transverse waves along a single flux tube are approximately one order of magnitude higher than those carried by linear longitudinal tube waves. The obtained results can be used to construct theoretical models of stellar chromospheres and winds.

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Nonlinear Alfven Wave Propagation in the Solar Wind

Cited by 27 publications

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Reflection of Alfvén waves in the corona and solar wind: An impulse function approach

Reflection of Alfvén waves in the corona and solar wind: An impulse function approach

Parametric decay of circularly polarized Alfvén waves in the radially expanding solar wind

Excitation of transverse magnetic tube waves in stellar convection zones

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