Lower hybrid resonances stimulated by the four CLUSTER relaxation sounders deep inside the plasmasphere: observations and inferred plasma characteristics

Kougblénou, S.; Lointier, G.; Décréau, Pierrette; Trotignon, Jean-Gabriel; Rauch, Jean-Louis; Vallières, Xavier; Canu, P.; Masson, A.; Pickett, J. S.

doi:10.5194/angeo-29-2003-2011

Cited by 12 publications

(16 citation statements)

References 46 publications

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“…We analyze the frequency spectra obtained during the passive and active (sounding) operation modes. Several methods can be used to determine F p , for example, the local wave cutoff properties [ Canu et al ., ], the observation of Bernstein modes [ Trotignon et al ., ], or the use of lower hybrid resonances [ Kougblénou and Lointier , ]. This analysis carries out a direct or indirect determination of N e related to F p by the relation

N_{e} {cm}^{- 3} = Fp {kHz}^{2} / 81

…”

Section: Cluster Data Analysismentioning

confidence: 99%

Links between the plasmapause and the radiation belt boundaries as observed by the instruments CIS, RAPID, and WHISPER onboard Cluster

et al. 2013

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[1] In the present work, we study the relations between the position of the plasmapause and the position of the radiation belt boundaries. The Cluster mission offers the exceptional opportunity to analyze those different regions of the inner magnetosphere with identical sensors on multiple spacecraft. We compare the positions of the radiation belt edges deduced from CIS (Cluster Ion Spectrometry) observations (electrons with energy > 2 MeV) with the positions of the plasmapause derived from WHISPER (Waves of HIgh frequency and Sounder for Probing of the Electron density by Relaxation) data (electron plasma frequency). In addition, we compare those results with the edges positions determined from RAPID (Research with Adaptive Particle Imaging Detectors) observations (electrons with energy between 244.1 and 406.5 keV). The period of 1 April 2007 to 31 March 2009 has been chosen for the analysis because at that time Cluster's perigee was located at lower radial distances than during the earlier part of the mission. The perigee was then as close as 2 R E , deep inside the plasmasphere and the radiation belts. This time period corresponds to a long solar activity minimum. Differences are observed between the radiation belt boundary positions obtained from the two different instruments: The radiation belt positions are related to the energy bands. The results show that the plasmapause position is more variable than the radiation belt boundary positions, especially during small geomagnetic activity enhancements. A correspondence is observed between the plasmapause position determined by WHISPER and the outer edge of the outer radiation belt of energetic electrons (> 2 MeV) observed by CIS. This result is unexpected since previous studies based on other spacecraft observations indicated a correlation between the inner edge of the outer belt and the plasmapause. However, during higher geomagnetic activity time periods, the plasmapause is located closer to the inner boundary of the outer radiation belt. Also, the thickness of the slot region is found to follow the global evolution of the geomagnetic activity.

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N_{e} {cm}^{- 3} = Fp {kHz}^{2} / 81

…”

Section: Cluster Data Analysismentioning

confidence: 99%

Links between the plasmapause and the radiation belt boundaries as observed by the instruments CIS, RAPID, and WHISPER onboard Cluster

et al. 2013

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“…Note that local wave cut-off properties can also be used to determine F pe . We can further mention the lower hybrid frequency, F lh , observed since 2009 at altitudes below ∼ 4000 km (Kougblénou et al, 2011).…”

Section: Electron Density Determinationmentioning

confidence: 99%

“…The spacecraft do not enter and leave the plasmasphere at similar MLT values but sweep a significant range of MLT values. Moreover, the latitudinal range explored during the crossing is smaller than at the start of the mission (see also Kougblénou et al, 2011, for a discussion about the Cluster orbit evolution). As the perigee geocentric distance decreases (from 4.2 R E at launch time to 1.5 R E in 2010), similar Z-values of perigee lead to higher latitudes www.ann-geophys.net/31/217/2013/ Ann.…”

Section: Cluster Plasmaspheric Coveragementioning

confidence: 99%

Refilling process in the plasmasphere: a 3-D statistical characterization based on Cluster density observations

Lointier¹,

Darrouzet

Décréau³

et al. 2013

Ann. Geophys.

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Abstract. The Cluster mission offers an excellent opportunity to investigate the evolution of the plasma population in a large part of the inner magnetosphere, explored near its orbit's perigee, over a complete solar cycle. The WHISPER sounder, on board each satellite of the mission, is particularly suitable to study the electron density in this region, between 0.2 and 80 cm−3. Compiling WHISPER observations during 1339 perigee passes distributed over more than three years of the Cluster mission, we present first results of a statistical analysis dedicated to the study of the electron density morphology and dynamics along and across magnetic field lines between L = 2 and L = 10. In this study, we examine a specific topic: the refilling of the plasmasphere and trough regions during extended periods of quiet magnetic conditions. To do so, we survey the evolution of the ap index during the days preceding each perigee crossing and sort out electron density profiles along the orbit according to three classes, namely after respectively less than 2 days, between 2 and 4 days, and more than 4 days of quiet magnetic conditions (ap ≤ 15 nT) following an active episode (ap > 15 nT). This leads to three independent data subsets. Comparisons between density distributions in the 3-D plasmasphere and trough regions at the three stages of quiet magnetosphere provide novel views about the distribution of matter inside the inner magnetosphere during several days of low activity. Clear signatures of a refilling process inside an expended plasmasphere in formation are noted. A plasmapause-like boundary, at L ~ 6 for all MLT sectors, is formed after 3 to 4 days and expends somewhat further after that. In the outer part of the plasmasphere (L ~ 8), latitudinal profiles of median density values vary essentially according to the MLT sector considered rather than according to the refilling duration. The shape of these density profiles indicates that magnetic flux tubes are not fully replenished after 6 days of quiet conditions. In addition, the outer plasmasphere in the night and dawn sectors (22:00 to 10:00 MLT range) maintains an overall clear deficit of ionospheric population, when compared to the situation in the noon and dusk sectors (10:00 to 22:00 MLT range).

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“…Several methods can be used to determine the electron plasma frequency F pe from the data recorded by the WHISPER instrument: the identification of local wave cut-off properties (Canu et al 2001), the observation of Bernstein modes (Trotignon et al 2003) or the use of lower hybrid resonances (Kougblénou et al 2011). This analysis carries out a direct or indirect determination of the electron density N e related to F pe by the simple relation:…”

Section: Cluster/whispermentioning

confidence: 99%

The ESPAS e-infrastructure: Access to data from near-Earth space

2017

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University College London (UCL) has conducted research on the upper atmosphere of the arctic auroral regions since the 1960s, contributing with both observational and modelling studies. In terms of observations, UCL has designed and built its own Fabry-Pérot Interferometer (FPI) instruments and deployed a network of these in Northern Scandinavia since the beginning of the 1980s. Meanwhile on the modelling side, UCL has developed so-called General Circulation Model (GCM) of the upper atmosphere/ionosphere coupled system, originally for the Earth, leading to the current CMAT2, but also for several other solar system bodies like Mars, the gas giants Jupiter and Saturn, and the latter's largest moon Titan, and a Jupiter-type exoplanet. This paper describes the contribution of UCL to the ESPAS project, with data from the FPI, and CMAT2, and work on the preliminary result of an ESPAS use case study in conjunction with the Met Office to compare FPI and CMAT2 data.

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Lower hybrid resonances stimulated by the four CLUSTER relaxation sounders deep inside the plasmasphere: observations and inferred plasma characteristics

Cited by 12 publications

References 46 publications

Links between the plasmapause and the radiation belt boundaries as observed by the instruments CIS, RAPID, and WHISPER onboard Cluster

Links between the plasmapause and the radiation belt boundaries as observed by the instruments CIS, RAPID, and WHISPER onboard Cluster

Refilling process in the plasmasphere: a 3-D statistical characterization based on Cluster density observations

The ESPAS e-infrastructure: Access to data from near-Earth space

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