Properties of magnetohydrodynamic turbulence in the solar wind as observed by Ulysses at high heliographic latitudes

Goldstein, B. E.; Smith, E. J.; Balogh, A.; Horbury, T. S.; Goldstein, M. L.; Roberts, D. A.

doi:10.1029/95gl03183

Cited by 137 publications

(111 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is more apparent in the N and T components; the R component seeming relatively unaffected. This is consistent with the work of Goldstein et al (1995a), who also observed a stronger radial, rather than latitudinal, dependence of the turbulent properties.…”

Section: Generalized Structure Functionssupporting

confidence: 93%

“…The inertial range fluctuations, and the crossover to f À1 behavior, show secular variation with heliographic distance (Horbury et al 1996a) consistent with evolving, rather than fully evolved, turbulence. Helios data, in conjunction with Ulysses, has been used by Goldstein et al (1995a) to show that the f À1 region contains scales that are too large to be produced in situ and that are progressively eaten away by the smaller scale turbulence, which must therefore be active. The large-scale magnetic structure of the corona also varies with both heliospheric latitude and solar cycle, and this is clearly manifested in the coherent structures and variation of wind speed that are observed ( Phillips et al 1995).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The Signature of Evolving Turbulence in Quiet Solar Wind as Seen byUlysses

Nicol

Chapman

Dendy

2008

ApJ

View full text Add to dashboard Cite

Solar wind fluctuations, such as magnetic field or velocity, show power-law power spectra suggestive both of an inertial range of intermittent turbulence (with $À5/3 exponent), and at lower frequencies, of fluctuations of coronal origin (with $À1 exponent). The Ulysses spacecraft spent many months in the quiet fast solar wind above the Sun's polar coronal holes in a highly ordered magnetic field. We use statistical analysis methods such as the generalized structure function (GSF ) and extended self-similarity (ESS) to quantify the scaling of the moments of the probability density function of fluctuations in the magnetic field. The GSFs give power law scaling in the f À1 range of the form hj y(t þ ) À y(t)j m i $ (m) , but ESS is required to reveal scaling in the inertial range, which is of the form hj y(t þ ) À y(t)j m i $ ½g( ) (m) . We find that g( ) is independent of spacecraft position and g( ) $ À log 10 (k ) . The f À1 scaling fluctuates with radial spacecraft position. This confirms that, whereas the f À1 fluctuations are directly influenced by the corona, the inertial range fluctuations are consistent with locally evolving turbulence, but with an envelope g( ), which captures the formation of the quiet fast solar wind.

show abstract

Section: Generalized Structure Functionssupporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

The Signature of Evolving Turbulence in Quiet Solar Wind as Seen byUlysses

Nicol

Chapman

Dendy

2008

ApJ

View full text Add to dashboard Cite

show abstract

“…Thus in addition to the well-established result [e.g., Goldstein ½t al., 1995b] that the turbulence evolution in the polar wind is slow as compared to that in lowlatitude wind, our analysis clearly indicates that such evolution, in terms of ere and Cvs, tends to become negligible beyond 3 AU. At these distances, (_.•,.rB typically spans fi'om 0.4 to 0.6.…”

supporting

confidence: 68%

Alfvénic turbulence in the polar wind: A statistical study on cross helicity and residual energy variations

Bavassano¹,

Pietropaolo²,

Bruno³

2000

J. Geophys. Res.

View full text Add to dashboard Cite

Abstract.A study of MHD turbulence properties in the polar wind has been performed with Ulysses data. The parameters under examination are the normalized cross hellcity and the normalized residual energy. The correlation coefficient between velocity and magnetic field fluctuation vectors has also been computed. Both southern and northern phases of full immersion in the high-latitude fast wind have been examined. Observations during the short low-latitude phase around the Ulysses perihelion have been used as a term of comparison. Our results indicate that in the region up to about 2 AU the turbulence evolution leads to a decrease of cross helicity and Alfvanic correlation when distance increases. Farther out no appreciable va, riation is observed. It is concluded that in the high-la. titude hellosphere the MHD turbulence maintains a clea,r Alfvanic character even at large dista,nces. As regards the residual energy, a clea,r imba, la[nce in favor of the magnetic fluctuations is everywhere present. This imbalance becomes even more pronounced for increasing distance inside 2 AU, due to turbulence evolution. Other effects lead to an inversion of this trend in the outer region. It is noteworthy that the polar turbulence does not appear too different from that observed inside the trailing edge of low-latitude fast streams.

show abstract

“…Our results will suggest natural explanations for the tendency of Alfvén waves in the corona and solar wind to be dominated by long periods, of the order of an hour, and for the tendency of outward propagating Alfvén waves to become less dominant at greater distances from the Sun. We will also find a tendency for the waves to have |dV A | > |dV|, as is generally observed in the solar wind [e.g., Goldstein et al, 1995]. We will also discuss an error in the literature [Hollweg, 1990a].…”

Section: Introductionmentioning

confidence: 57%

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

Hollweg

Isenberg

2007

J. Geophys. Res.

View full text Add to dashboard Cite

[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.

show abstract

Properties of magnetohydrodynamic turbulence in the solar wind as observed by Ulysses at high heliographic latitudes

Cited by 137 publications

References 29 publications

The Signature of Evolving Turbulence in Quiet Solar Wind as Seen byUlysses

The Signature of Evolving Turbulence in Quiet Solar Wind as Seen byUlysses

Alfvénic turbulence in the polar wind: A statistical study on cross helicity and residual energy variations

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

Contact Info

Product

Resources

About