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The Effect of the Plasmasphere on ULF Waves: Potential Studies With Global ULF pulsations in the inner magnetosphere: Lessons learned from earlier missions and potential studies with RBSP Michael Hartinger1,2, Vassilis Angelopoulos1, Mark Moldwin2 1UCLA 2University of Michigan Advantages of RBSP •The plasmapause is typically located at 4-5 Re •Geocentric apogee of RBSP is 5.8 Re •RBSP will be ideal for wave studies inside the plasmasphere, at the plasmapause, and just outside the plasmapause •RBSP ion composition measurements and measurements of electron density from fuhr will be very useful – they can be used to identify the plasmapause and calculate the Alfven speed •There are many possible areas for RBSP to add to previous ULF wave studies – 3 potential areas are energy transfer across the plasmapause, plasmapause surface waves, and global modes 1 – Energy transfer across the plasmapause [Lee, 1996] ω =| k |VA (r) ≥ ωmin = kφ (r)VA (r) [NASA] •Several models have shown that the plasmapause can act as a barrier for fast mode transmission from the outer to the inner magnetosphere 1 - Case Study using CRRES [Hartinger et al., 2010] 1 - Statistical Results [Hartinger et al., 2010] 1 - THEMIS example [Hartinger et al., 2012] RBSP conjunctions for studying radial energy transfer •Multi-point RBSP observations at or near the plasmapause can be used to study radial energy transfer and wave mode coupling •Is there larger amplitude wave activity outside/near the plasmapause? How does it affect radiation belt electrons and VLF waves? 2 - Global modes [Lee et al., 2004] •There were a number of cavity mode observations made with CRRES (e.g., Goldstein et al., 1999, Denton et al., 2002) 2 - THEMIS observations of plasmaspheric global modes [Takahashi et al., 2010] 2 – THEMIS observations of global modes outside the plasmasphere [Hartinger et al., 2012] Conjunctions for studying radial energy transfer and spatial extent [Sibeck, RBSP white paper] *RBSP can be used to better characterize plasmaspheric global modes with more observations and better knowledge of the Alfven speed profile *RBSP and THEMIS (or CLUSTER) can be used to identify whether global modes extend throughout the magnetosphere and if they play an important role in the transport of radiation belt electrons 3 - Plasmapause surface waves [Daly and Hughes, 1985] 3 - CRRES surface wave observations [LeDocq et al., 1994] •Sometimes CRRES observed •Other times CRRES observed monochromatic density fluctuations turbulent fluctuations Conjunction for studying surface waves •Multi-point observations at the plasmapause can be used to identify and characterize surface wave activity, especially when one or both RBSP probes are near apogee •Assess how the modulation in density affects VLF waves 4 - Effect of ion composition on MHD waves: magnetoseismology [Takahashi et al., 2008] RBSP configurations [surface wave, plumes] [radial/time evolution structure of waves] Backup: Two fluid L mode (parallel) X mode (perpendicular) R mode (parallel) [Boyd and Sanderson, 2003] Backup: Two fluid, oblique, warm plasma [Boyd and Sanderson, 2003] Backup: MHD phase velocities [Baumjohann and Treumann, 1996] Backup – CRRES data coverage Possible surface wave observations with other missions •Cluster and IMAGE have also observed indications of surface wave activity (e.g., [Liu et al., 2011] Darrouzet et al., 2009) Sources of low-latitude Pi2 pulsations: CRRES observations [Takahashi et al., 2003] Sources of low-latitude Pi2 pulsations: THEMIS observations [Luo et al., 2011] •Some THEMIS observations confirm plasmaspheric cavity modes as the source of low-latitude Pi2, whereas others (e.g., Nishimura recent results) do not EMIC wave occurrence [Kawamura et al., 1982; obtained from Fraser and Nguyen, 2000] [Fraser and Nguyen, 2000] EMIC/MHD waves and plumes [Morley et al., 2009] Pg event example – 10/19/2008 (reported by Kazue et al., 2011) Pg event example – 10/19/2008 (reported by Kazue et al., 2011) Pg event example – 2010/02/22 Pg event example – 2010/02/22 Pg event example – 2010/02/22 Pg event example – 2010/01/28 Pg event example – 2010/01/28 Pg event example – 2010/01/28 Pg event example – 2010/02/06 Pg event example – 2010/02/06 Pg event example – 2010/02/06 Pg event example – 2010/02/06 Pg event example – 2010/02/06 .
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