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Statistics of a parallel Poynting vector in the auroral zone as a function of altitude using Polar EFI and MFE data and Astrid-2 EMMA data. / Janhunen, P; Olsson, A; Tsyganenko, NA; Russell, CT; Laakso, H; Blomberg, LG.

In: Annales Geophysicae, Vol. 23, No. 5, 2005, p. 1797-1806.

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Janhunen, P ; Olsson, A ; Tsyganenko, NA ; Russell, CT ; Laakso, H ; Blomberg, LG. / Statistics of a parallel Poynting vector in the auroral zone as a function of altitude using Polar EFI and MFE data and Astrid-2 EMMA data. In: Annales Geophysicae. 2005 ; Vol. 23, No. 5. pp. 1797-1806.

BibTeX

@article{c78c86ce2c9f43a093085992bac0cb86,
title = "Statistics of a parallel Poynting vector in the auroral zone as a function of altitude using Polar EFI and MFE data and Astrid-2 EMMA data",
abstract = "We study the wave-related (AC) and static (DC) parallel Poynting vector (Poynting energy flux) as a function of altitude in auroral field lines using Polar EFI and MFE data. The study is statistical and contains 5 years of data in the altitude range 5000-30 000km. We verify the low altitude part of the results by comparison with earlier Astrid-2 EMMA Poynting vector statistics at 1000km altitude. The EMMA data are also used to statistically compensate the Polar results for the missing zonal electric field component. We compare the Poynting vector with previous statistical DMSP satellite data concerning the electron precipitation power. We find that the AC Poynting vector (Alfvenwave related Poynting vector) is statistically not sufficient to power auroral electron precipitation, although it may, for K-P > 2, power 25-50% of it. The statistical AC Poynting vector also has a stepwise transition at R=4 R-E, so that its amplitude increases with increasing altitude. We suggest that this corresponds to Alfven waves being in Landau resonance with electrons, so that wave-induced electron acceleration takes place at this altitude range, which was earlier named the Alfven Resonosphere (ARS). The DC Poynting vector is similar to 3 times larger than electron precipitation and corresponds mainly to ionospheric Joule heating. In the morning sector (02:00-06:00 MLT) we find that the DC Poynting vector has a nontrivial altitude profile such that it decreases by a factor of similar to 2 when moving upward from 3 to 4 RE radial distance. In other nightside MLT sectors the altitude profile is more uniform. The morning sector nontrivial altitude profile may be due to divergence",
keywords = "magnetospheric physics, auroral phenomena, magnetosphere-ionosphere interactions, space plasma physics, wave-particle interactions, ELECTRIC-FIELDS, FLUX, SATELLITE, FREQUENCY, DE-2, auroral phenomena, magnetosphere, electron beam, ALFVEN WAVES",
author = "P Janhunen and A Olsson and NA Tsyganenko and CT Russell and H Laakso and LG Blomberg",
year = "2005",
doi = "10.5194/angeo-23-1797-2005",
language = "English",
volume = "23",
pages = "1797--1806",
journal = "Annales Geophysicae",
issn = "0992-7689",
publisher = "Copernicus GmbH ",
number = "5",

}

RIS

TY - JOUR

T1 - Statistics of a parallel Poynting vector in the auroral zone as a function of altitude using Polar EFI and MFE data and Astrid-2 EMMA data

AU - Janhunen, P

AU - Olsson, A

AU - Tsyganenko, NA

AU - Russell, CT

AU - Laakso, H

AU - Blomberg, LG

PY - 2005

Y1 - 2005

N2 - We study the wave-related (AC) and static (DC) parallel Poynting vector (Poynting energy flux) as a function of altitude in auroral field lines using Polar EFI and MFE data. The study is statistical and contains 5 years of data in the altitude range 5000-30 000km. We verify the low altitude part of the results by comparison with earlier Astrid-2 EMMA Poynting vector statistics at 1000km altitude. The EMMA data are also used to statistically compensate the Polar results for the missing zonal electric field component. We compare the Poynting vector with previous statistical DMSP satellite data concerning the electron precipitation power. We find that the AC Poynting vector (Alfvenwave related Poynting vector) is statistically not sufficient to power auroral electron precipitation, although it may, for K-P > 2, power 25-50% of it. The statistical AC Poynting vector also has a stepwise transition at R=4 R-E, so that its amplitude increases with increasing altitude. We suggest that this corresponds to Alfven waves being in Landau resonance with electrons, so that wave-induced electron acceleration takes place at this altitude range, which was earlier named the Alfven Resonosphere (ARS). The DC Poynting vector is similar to 3 times larger than electron precipitation and corresponds mainly to ionospheric Joule heating. In the morning sector (02:00-06:00 MLT) we find that the DC Poynting vector has a nontrivial altitude profile such that it decreases by a factor of similar to 2 when moving upward from 3 to 4 RE radial distance. In other nightside MLT sectors the altitude profile is more uniform. The morning sector nontrivial altitude profile may be due to divergence

AB - We study the wave-related (AC) and static (DC) parallel Poynting vector (Poynting energy flux) as a function of altitude in auroral field lines using Polar EFI and MFE data. The study is statistical and contains 5 years of data in the altitude range 5000-30 000km. We verify the low altitude part of the results by comparison with earlier Astrid-2 EMMA Poynting vector statistics at 1000km altitude. The EMMA data are also used to statistically compensate the Polar results for the missing zonal electric field component. We compare the Poynting vector with previous statistical DMSP satellite data concerning the electron precipitation power. We find that the AC Poynting vector (Alfvenwave related Poynting vector) is statistically not sufficient to power auroral electron precipitation, although it may, for K-P > 2, power 25-50% of it. The statistical AC Poynting vector also has a stepwise transition at R=4 R-E, so that its amplitude increases with increasing altitude. We suggest that this corresponds to Alfven waves being in Landau resonance with electrons, so that wave-induced electron acceleration takes place at this altitude range, which was earlier named the Alfven Resonosphere (ARS). The DC Poynting vector is similar to 3 times larger than electron precipitation and corresponds mainly to ionospheric Joule heating. In the morning sector (02:00-06:00 MLT) we find that the DC Poynting vector has a nontrivial altitude profile such that it decreases by a factor of similar to 2 when moving upward from 3 to 4 RE radial distance. In other nightside MLT sectors the altitude profile is more uniform. The morning sector nontrivial altitude profile may be due to divergence

KW - magnetospheric physics

KW - auroral phenomena

KW - magnetosphere-ionosphere interactions

KW - space plasma physics

KW - wave-particle interactions

KW - ELECTRIC-FIELDS

KW - FLUX

KW - SATELLITE

KW - FREQUENCY

KW - DE-2

KW - auroral phenomena

KW - magnetosphere

KW - electron beam

KW - ALFVEN WAVES

U2 - 10.5194/angeo-23-1797-2005

DO - 10.5194/angeo-23-1797-2005

M3 - Article

VL - 23

SP - 1797

EP - 1806

JO - Annales Geophysicae

JF - Annales Geophysicae

SN - 0992-7689

IS - 5

ER -

ID: 28045980