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Etudes statistiques de la puissance des ondes à la magnétopause et à son voisinage (Traversées Cluster). Corrélations avec la pression du vent solaire.David Attié, Nicole Cornilleau-wehrlin, Gérard Belmont, Laurence RezeauC.E.T.P (Vélizy)Traversées 2001-2003 (Attié et al 2006,JGR, en révision)Traversées 2004-2005 (Groupe thématique)
Crossings distribution in YZ plane(GSE frame). • Period July 2001 to June 2003. • Magnetopause crossings by CLUSTER either on the day side at high latitudes, or at low latitude on the flanks.
Cluster 1 whisper (natural) Freq(Hz) Staff-sc (B2z,sr2) Freq(Hz) fgm Bx (nT) By Bz (gse) CLUSTER 1, 2001/02/14, MP crossing • Statistics on MP and adjacent MSH wave power. • Wave power and amplification at the MP. • External source for MP wave activity? • Role of B rotation?
Role of B rotation in wave power and amplification • Wave power Strong correlation between wave power and B rotation at the MP. P*max nT2 (deg) • Amplification into the boundary (deg) Weak amplification (low rotation) Strong amplification (high rotation) (deg)
B rotation and wave power calculation. Peak power Pmax(nT2) B power (0.35-10 Hz, STAFF), 1s resolution. BL,LMN frame (FGM) B rotation (LM plane) Average power Pmsh(nT2) nT2 nT (deg) Time(HH:MN:SS)
Solar wind influence (years 2001-2003) Normalized power (0.35-10Hz) The wave power in MSH is correlated with the solar wind dynamic pressure (thanks to ACE data). Such a behaviour might take part of driven reconnection scenarios. P*msh Solar wind dynamic pressure(nPa)
Solar wind influence (years 2004-2005) Normalized power (0.35-10Hz) 7-11 nov 2004 1 janv 2005 P*msh Solar wind dynamic pressure(nPa)
Solar wind influence (years 2004-2005) Normalized power (0.35-10Hz) 7-11 nov 2004 1 janv 2005 P*msh Subsolar point (distance in Re, Sibeck model)
Evidence of an external source The wave power is normalized to the local magnetic field. An amplification and a strong correlation appears between the turbulence level of MP and MSH . Turbulence in MSH can be see as an external source to the high wave activity at the MP. P*max y=21x1.12, r=0.96 P*msh