On the distribution of energy versus Alfvénic correlation for polar wind fluctuations

Previous analyses have shown that polar wind fluctuations at MHD scales appear as a mixture of Alfvénic fluctuations and variations with an energy imbalance in favour of the magnetic term. In the present study, by separately examining the behaviour of kinetic and magnetic energies versus the Alfv...

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Main Authors: B. Bavassano, R. Bruno
Format: Article
Language:English
Published: Copernicus Publications 2006-11-01
Series:Annales Geophysicae
Online Access:https://www.ann-geophys.net/24/3179/2006/angeo-24-3179-2006.pdf
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author B. Bavassano
R. Bruno
author_facet B. Bavassano
R. Bruno
author_sort B. Bavassano
collection DOAJ
description Previous analyses have shown that polar wind fluctuations at MHD scales appear as a mixture of Alfvénic fluctuations and variations with an energy imbalance in favour of the magnetic term. In the present study, by separately examining the behaviour of kinetic and magnetic energies versus the Alfvénic correlation level, we unambiguously confirm that the second population is essentially related to a large increase of the magnetic energy with respect to that of the Alfvénic population. The relevant new result is that this magnetic population, though of secondary importance in terms of occurrence frequency, corresponds to a primary peak in the distribution of total energy. The fact that this holds in the case of polar wind, which is the least structured type of interplanetary plasma flow and with the slowest evolving Alfvénic turbulence, strongly suggests the general conclusion that magnetic structures cannot be neglected when modeling fluctuations for all kinds of wind regime.
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spelling doaj.art-51a15dd5320a4be5909350c4f59cfb732022-12-22T03:37:43ZengCopernicus PublicationsAnnales Geophysicae0992-76891432-05762006-11-01243179318410.5194/angeo-24-3179-2006On the distribution of energy versus Alfvénic correlation for polar wind fluctuationsB. Bavassano0R. Bruno1Istituto di Fisica dello Spazio Interplanetario, Istituto Nazionale di Astrofisica, Rome, ItalyIstituto di Fisica dello Spazio Interplanetario, Istituto Nazionale di Astrofisica, Rome, ItalyPrevious analyses have shown that polar wind fluctuations at MHD scales appear as a mixture of Alfvénic fluctuations and variations with an energy imbalance in favour of the magnetic term. In the present study, by separately examining the behaviour of kinetic and magnetic energies versus the Alfvénic correlation level, we unambiguously confirm that the second population is essentially related to a large increase of the magnetic energy with respect to that of the Alfvénic population. The relevant new result is that this magnetic population, though of secondary importance in terms of occurrence frequency, corresponds to a primary peak in the distribution of total energy. The fact that this holds in the case of polar wind, which is the least structured type of interplanetary plasma flow and with the slowest evolving Alfvénic turbulence, strongly suggests the general conclusion that magnetic structures cannot be neglected when modeling fluctuations for all kinds of wind regime.https://www.ann-geophys.net/24/3179/2006/angeo-24-3179-2006.pdf
spellingShingle B. Bavassano
R. Bruno
On the distribution of energy versus Alfvénic correlation for polar wind fluctuations
Annales Geophysicae
title On the distribution of energy versus Alfvénic correlation for polar wind fluctuations
title_full On the distribution of energy versus Alfvénic correlation for polar wind fluctuations
title_fullStr On the distribution of energy versus Alfvénic correlation for polar wind fluctuations
title_full_unstemmed On the distribution of energy versus Alfvénic correlation for polar wind fluctuations
title_short On the distribution of energy versus Alfvénic correlation for polar wind fluctuations
title_sort on the distribution of energy versus alfvenic correlation for polar wind fluctuations
url https://www.ann-geophys.net/24/3179/2006/angeo-24-3179-2006.pdf
work_keys_str_mv AT bbavassano onthedistributionofenergyversusalfveniccorrelationforpolarwindfluctuations
AT rbruno onthedistributionofenergyversusalfveniccorrelationforpolarwindfluctuations