Observation of isolated high-speed auroral streamers and their interpretation as optical signatures of Alfvén waves generated by bursty bulk flows

2008 ◽  
Vol 35 (4) ◽  
Author(s):  
W. W. Liu ◽  
J. Liang ◽  
E. F. Donovan ◽  
T. Trondsen ◽  
G. Baker ◽  
...  
Keyword(s):  
High Speed ◽  
Alfven Waves ◽  
Alfvén Waves ◽  
Bursty Bulk Flows

scholarly journals High-intensity, long-duration, continuous AE activity events associated with Alfvénic fluctuations in 2003

2017 ◽  
Vol 35 (6) ◽  
pp. 1231-1240 ◽  
Author(s):  
Alan Prestes ◽  
Virginia Klausner ◽  
Arian Ojeda-González
Keyword(s):  
Magnetic Field ◽  
High Intensity ◽  
High Speed ◽  
Cross Correlation ◽  
Alfven Waves ◽  
Alfvén Waves ◽  
Superposed Epoch Analysis ◽  
Fast Speed ◽  
Long Duration ◽  
Epoch Analysis

Abstract. The interaction between a fast-speed and a low-speed stream causes large-amplitude Alfvénic fluctuations; consequently, the intermittency and the brief intervals of southward magnetic field associated with Alfvén waves may cause high levels of AE activity, the so-called high-intensity, long-duration, continuous AE activity (HILDCAA). In this article, the 4 h windowed Pearson cross-correlation (4WPCC) between the solar wind velocity and the interplanetary magnetic field (IMF) components is performed in order to confirm that the less strict HILDCAA (HILDCAAs*) events include a larger number of Alfvén waves than the HILDCAA events, once HILDCAAs disregard part of the phenomenon. Actually, a HILDCAA event is entirely contained within a HILDCAA* event. However, the opposite is not necessarily true. This article provides a new insight, since the increase of Alfvén waves results in an increase of auroral electrojet activity; consequently, it can cause HILDCAAs* events. Another important aspect of this article is that the superposed epoch analysis (SEA) results reaffirm that the HILDCAAs* are associated with high-speed solar streams (HSSs), and also the HILDCAAs* present the same physical characteristics of the traditional HILDCAA events.

scholarly journals A study of phase-steepened Alfvén waves in a high-speed stream at 0.29 AU

2000 ◽  
Vol 18 (8) ◽  
pp. 845-851 ◽  
Author(s):  
P. Alexander
Keyword(s):  
Solar Wind ◽  
High Speed ◽  
A Priori ◽  
Solar Wind Plasma ◽  
Alfven Waves ◽  
Mhd Waves ◽  
Alfvén Waves ◽  
Interplanetary Physics ◽  
Speed Solar Wind ◽  
High Speed Solar Wind

Abstract. This work performs a search of phase-steepened Alfvén waves under a priori ideal conditions: a high-speed solar wind stream observed in one of the closest approaches to the Sun by any spacecraft (Helios 2). Five potential candidates were initially found following procedures established in earlier work. The observed cases exhibited arc-like or elliptical polarizations, and the rotational discontinuities that formed the abrupt wave edges were found at either the leading or the trailing part. The consideration of some additional specific parameters (mainly related to the relative orientation between mean magnetic field, wave and discontinuity) has been suggested here for an ultimate and proper identification of this kind of phenomenon. After the inclusion of these calculations in our analysis, even fewer cases than the five originals remain. It is suggested that optimum conditions for the detection rather than just for the existence of these events have to be reconsidered.Key words: Interplanetary physics (discontinuities; MHD waves and turbulence; solar wind plasma)

scholarly journals Acceleration of the Solar Wind: A New View

1998 ◽  
Vol 11 (2) ◽  
pp. 838-841
Author(s):  
V.H. Hansteen ◽  
E. Leer
Keyword(s):  
Solar Wind ◽  
High Speed ◽  
Alfven Waves ◽  
Alfvén Waves ◽  
New Models ◽  
New View

The last few years have seen the development of solar wind models characterized by high coronal proton temperatures, low electron temperatures and low densities in the inner corona. In addition the emphasis on “additional” acceleration via Alfvén waves has been muted and been replaced by models where the acceleration is essentially complete within 1OR0. This work has, in part, been spurred by Ulysses observations of the high speed wind and by the expectations of the observations to be made by the various instruments on the SOHO satellite. In this paper we show how these new models differ from earlier ones.

Spatial transport and spectral transfer of solar wind turbulence composed of Alfvén waves and convective structures II: numerical results

1995 ◽  
Vol 13 (5) ◽  
pp. 475-493 ◽  
Author(s):  
J. M. Schmidt
Keyword(s):  
Solar Wind ◽  
High Speed ◽  
Alfven Waves ◽  
Numerical Results ◽  
Alfvén Waves ◽  
Convective Structures ◽  
Solar Wind Turbulence ◽  
Wind Turbulence ◽  
Speed Solar Wind ◽  
High Speed Solar Wind

Abstract. This work follows the paper titled "Spatial transport and spectral transfer of solar wind turbulence composed of Alfvén waves and convective structures I: The theoretical model", and deals with the detailed physics and numerical solution of a two-component solar wind model, consisting of small-scale Alfvén waves and convected structures. In particular, we present numerical results which qualitatively reflect many of the observed features of the radial and spectral evolution of the turbulent energies, the residual energy, the cross-helicity and Alfvén-ratio in high-speed solar wind streams. These features are the following: the formation of a characteristic "inclined eye", which evolves between the energy spectra displayed over the frequency axis and tends to close in the radial development of the spectra, a steepening of all spectra towards Kolmogorov-like f-5/3 spectra, the development of the normalized cross-helicity towards a constant not much less than one and the formation of a "trough" form of the Alfvén ratio with a z-shaped left boundary, By weighting special terms in the equations differently, we can also cast light on the physical role of parametric conversion model terms, wave-structure scattering model terms, nonlinear terms, spherical expansion terms and their effects on the radial evolution of turbulent energies in high-speed solar wind streams.

scholarly journals On the origin of solar wind. Alfvén waves induced jump of coronal temperature

2007 ◽  
Vol 44 (3) ◽  
pp. 533-536 ◽  
Author(s):  
T. M. Mishonov ◽  
M. V. Stoev ◽  
Y. G. Maneva
Keyword(s):  
Solar Wind ◽  
Alfven Waves ◽  
Alfvén Waves ◽  
Coronal Temperature

AMPTE/CCE observations of substorm-associated standing Alfvén waves in the midnight sector

1988 ◽  
Vol 15 (11) ◽  
pp. 1287-1290 ◽  
Author(s):  
K. Takahashi ◽  
S. Kokubun ◽  
T. Sakurai ◽  
R. W. McEntire ◽  
T. A. Potemra ◽  
...  
Keyword(s):  
Alfven Waves ◽  
Alfvén Waves
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