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dc.contributor.authorEchim, M.M.
dc.contributor.authorLamy, H.
dc.contributor.authorChang, T.
dc.date2007
dc.date.accessioned2016-09-27T11:09:46Z
dc.date.available2016-09-27T11:09:46Z
dc.identifier.urihttps://orfeo.belnet.be/handle/internal/4400
dc.descriptionIn this paper we investigate the statistical properties of magnetic field fluctuations measured by the four Cluster spacecraft in the cusp and close to the interface with the magnetospheric lobes, magnetopause and magnetosheath. At lower altitudes along the outbound orbit of 26 February 2001, the magnetic field fluctuations recorded by all four spacecraft are random and their Probability Distribution Functions (PDFs) are Gaussian at all scales. The flatness parameter, ℱ - related to the kurtosis of the time series, is equal to 3. At higher altitudes, in the cusp and its vicinity, closer to the interface with the magnetopause and magnetosheath, the PDFs from all Cluster satellites are non-Gaussian and show a clear intermittent behavior at scales smaller than τG≈61 S (or 170 km). The flatness parameter increases to values greater than 3 for scales smaller than τG. A Haar wavelet transform enables the identification of the "events" that produce sudden variations of the magnetic field and of the scales that have most of the power. The LIM parameter (i.e. normalized wavelet power) indicates that events for scales below 65 s are non-uniformly distributed throughout the cusp passage. PDFs, flatness and wavelet analysis show that at coarsegrained scales larger than τG the intermittency is absent in the cusp. Fluctuations of the magnetic energy observed during the same orbit in the magnetosheath show PDFs that tend toward a Gaussian at scales smaller than τG found in the cusp. The flatness analysis confirms the decreasing of τG from cusp to magnetosheath. Our analysis reveals the turbulent cusp as a transition region from a non-intermittent turbulent state inside the magnetosphere to an intermittent turbulent state in the magnetosheath that has statistical properties resembling the solar wind turbulence. The observed turbulent fluctuations in the cusp suggests a phenomenon of non-linear interactions of plasma coherent structures as in contemporary models of space plasma turbulence.
dc.languageeng
dc.relation.ispartofseries
dc.titleMulti-point observations of intermittency in the cusp regions
dc.typeArticle
dc.subject.frascatiPhysical sciences
dc.audienceScientific
dc.subject.freeGaussian method
dc.subject.freemagnetic anomaly
dc.subject.freemagnetic field
dc.subject.freemagnetopause
dc.subject.freemagnetosphere
dc.subject.freeprobability density function
dc.subject.freestatistical analysis
dc.subject.freeturbulence
dc.subject.freewavelet analysis
dc.source.titleNonlinear Processes in Geophysics
dc.source.volume14
dc.source.issue4
dc.source.page525-534
Orfeo.peerreviewedYes
dc.identifier.doi10.5194/npg-14-525-2007
dc.identifier.scopus2-s2.0-34548080667


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