Ring Current ation环电流的成

1、dynamics ofthe radiation belts & the ring currentioannis a. daglisinstitute for space applicationsathensdynamics of the near-space particle radiation environmentmain issue: mechanism(s) that can efficiently accelerate and/or transport charged particles, leading to -build-up of storm-time ring cu

2、rrent -enhanced fluxes of mev radiation belt electrons.dynamics of the near-space particle radiation environmentin both cases, the most obvious driverthe magnetospheric substormappears to be insufficient dynamics of radiation beltssubstorms produce electrons with energies of 10s to 100s of kev, but

3、only few of mev energies.dynamics of ring current(individual) substorms inject plenty of hot ions to the inner magnetosphere, but not enough to create/sustain the ring current.dynamics of the near-space particle radiation environmentpresumably, the ring current build-up and the radiation belt enhanc

4、ement, being processes of a higher level of complexity,display properties not evident at the lower levelsdynamics of radiation belts close association of storm-time enhancements of relativistic electron fluxes with spacecraft failure.spacecraft operational anomalies, sampex databaker & daglis, 2

5、006dynamics of radiation beltseach new mission in the inner ms brings new insights (sampex, crres)close correlation with storms / large dynamic range: 10 to 104 (li et al. 2001).location of the peak electron flux as a function of minimum dst moves to lower lobrien et al., jgr2003dynamics of radiatio

6、n beltsassociation of mev electrons with ulf waves / radial diffusion baker and daglis, 2006dynamics of radiation beltsgreen and kivelson, 2004 polar/hist data 1997-1999dynamics of radiation belts internal/external300-500 kev 1.1-1.5 mev300-500 kev 1.1-1.5 mevdstkpgeogps1.22 mevequatorial flux(l=4.2

7、)mev electron flux evolution after a storm equatorial fluxes reach max in:- 2.5 days at geo orbit- 16 hours at gps orbit equatorial fluxes reach max in:- 2 days at geo orbit- 6 days at gps orbitt=0t=0gps maxgps maxgeo maxgeo maxdynamics of radiation beltsvassiliadis et al., jgr 2002region p1: slow (

8、2-3-day) response to hi-speed streams characteristic of geo orbit prob. involves ulf waves representative study: paulikas and blake, 1979.region p0: rapid (1-day) response to magnetic clouds/icmes. characterizes l sum of individual effects)- feature of the emergent order of higher levels of complexi

9、tyfully understand and specify radiation belt variability(crres, bernie blake)dynamics of radiation belts - futurelexplain rapid acceleration of electrons to relativistic energieslidentify loss mechanismsldevelop accurate energetic electron modeldynamics of radiation belts - futurethe classical ring

10、 conceptimage courtesy hannu koskinen, fmiring current dynamics-rc sources (composition) / rc asymmetry-rc formation: imf driver-rc formation: role of substormsring current sources / compositiondaglis, magnetic storms monograph 1997fig. 6 of daglis et al. jgr2003ring current asymmetry a very asymmet

11、ric ring current distribution during the main and early recovery phases of an intense storm near dst minimum o+ becomes the dominant ion in agreement with previous observations of intense stormsjordanova et al. 2003 ring current asymmetry & ion compositionring current dynamics-rc sources (compos

12、ition) / rc asymmetry -rc formation: imf driver-rc formation: role of substormsring current formation imf driverempirical certainty:prolonged southward imf drives strong convection (westward ey) and therefore storms.large imf bs = intense storms.modeling (ram code: kozyra, liemohn, et al.)comparativ

13、e study of a solar-max and a solar-min intense storms: imf comparable.“resulting” dst different.ring current formation imf driverstorm intensity defined by imf bs size and duration? not exclusively!ring current formation imf driverring current dynamics-rc sources (composition) / rc asymmetry -rc for

14、mation: imf driver-rc formation: role of substormsring current formation substormsrole of substorms1960s chapman and akasofu: storms = cumulative result of substorms1990s mcpherron, iyemori, et al.: purely solar driven, no substorm influence2000s daglis, metallinou, fok, ganushkina, et al.: substorm

15、s act as catalystsdaglis 1997, 1999fig. 5 of ganushkina et al., anngeo2005ganushkina et al. showed that the observed h+ acceleration at high energies can be reproduced in modeling studies only through substorm-style induced e pulses.fig. 10 of ganushkina et al., anngeo2005substorm-induced transient

16、electric fields clearly contribute to particle accelerationring current formation substormsring current formation substormseffect of recurrent (periodic) substorms on particle accelerationring current formation substormsring current formation substormsring current formation substormsdynamics of ring

17、 currentnot simply a superposition, but a synergy of convection, substorm-induced electric fiels and wave-particle interactions (combined effect sum of individual effects) - - a feature of the emergent order of higher levels of complexitythe ring current is a very dynamic population, strongly coupli

18、ng the inner magnetosphere with the ionosphere, which is an “increasingly important” source and modulatorimf not the sole ruler: plasma sheet density, ionospheric outflow, substorm occurrence, all have their role in storm development.summary rcsubstorms act catalytically: they accelerate ions to hig

19、h(er) energies/ they preferentially accelerate o+ ions, which dominate during intense storms.storms, being phenomena of a higher level of complexity display properties not evident at the lower levels (substorms / convection)summary rcdynamics ofthe radiation belts & the ring currentendrb models need better satellite measurements:l particle measurements with full pitch-angle informationl comprehensive magnetic field measurementslwave measurementslparticle measurements in inner zonedynamics of radiation belts - futureknown problems: ae8 mode