Ring Current Formation环电流的形成
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Explain rapid acceleration of electrons to relativistic energies
Identify loss mechanisms Develop accurate energetic electron model
The classical ring concept
A very asymmetric 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 storms
Main issue: mechanism(s) that can efficiently accelerate and/or transport charged particles, leading to
-build-up of storm-time ring current
-enhanced fluxes of MeV radiation belt electrons.
Ring Current Sources / Composition Daglis, Magnetic Storms Monograph [2019]
Ring current asymmetry
Fig. 6 of Daglis et al. JGR2019
Ring Current Asymmetry & Ion Composition
Dynamics of Radiation Belts - Future Fully understand and specify radiation belt variability
(CRRES, Bernie Blake)
Dynamics of Radiation Belts - Future
Paulikas and Blake, 1979.
September 5, 2019 (Solar Min)
[Vassiliadis et al., JGR 2019]
Region P0: • Rapid (<1-day) response to magnetic clouds/ICMEs. • Characterizes L<4. • Representative events:
Dynamics of the Radiation Belts &
the Ring Current
Ioannis A. Daglis
Institute for Space Applications Athens
Dynamics of the near-space particle radiation environment
at the lower levels
Dynamicsቤተ መጻሕፍቲ ባይዱof Radiation Belts
Close association of storm-time enhancements of relativistic electron fluxes
with spacecraft failure.
Spacecraft operational anomalies, SAMPEX data [Baker & Daglis, 2019]
January 2019, May 2019: - Baker et al., GRL 2019; - Reeves et al., GRL 2019
May 4, 2019 (Solar Max)
Dynamics of Radiation Belts
O’Brien et al., JGR2019 SAMPEX, HEO-3 data / SAMNET, IMAGE
Dynamics of Radiation Belts
Close to GEO, ULF-wave enhanced radial diffusion is more important, pushing electrons inward and accelerating them.
Around L~5, VLF chorus waves accelerate electrons (microbursts) without displacing them in L.
MeV Electron Flux evolution after a Storm
Dst
Kp
300-500 keV 1.1-1.5 MeV
GEO
300-500 keV 1.1-1.5 MeV
GEO max
GPS max
T=0
GPS
1.22 MeV
equatorial flux
(L=4.2)
T=0
GEO max GPS max
8
7
1 MeV
6
L5
2. Plus chorus waves:
2100 MeV/G, equator, Kp =1.8
plasmapause
4
3 MeV
3
2
Iteration number
(MeV-3s-3)
1025 1024 1023 1022 1021 1020
Distribution Functions (MeV-3s-3)
Image courtesy Hannu Koskinen, FMI
Ring Current Dynamics
-RC sources (composition) / RC [a]symmetry
- RC formation: IMF driver - RC formation: role of substorms
Dynamics of Radiation Belts
Both ULF waves and microbursts are strongest during the main phase of storms, both progress to lower L during stronger magnetic activity, both continue to be active during the recovery phase of events, and both appear to be more active during intervals of high solar wind velocity.
Dynamics of Radiation Belts
Region P1: • Slow (2-3-day) response to hi-speed streams • Characteristic of GEO orbit • Prob. involves ULF waves • Representative study:
Substorms produce electrons with energies of 10s to 100s of keV, but 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 environment
Presumably, the ring current build-up and
the radiation belt enhancement,
being processes of a higher level of complexity, display properties not evident
Dynamics of the near-space particle radiation environment
In both cases, the most obvious driver
the magnetospheric substorm
appears to be insufficient
Dynamics of Radiation Belts
1.E+26 1.E+25 1.E+24 1.E+23 1.E+22 1.E+21 1.E+20
3
DLL and Chorus
DLL
Lpp
4
5
6
7
8
L
L=5.5: Values 100 times higher!
Varotsou et al.
Dynamics of Radiation Belts
Not simply a superposition, but a synergy of various lower-level processes (combined effect > sum of individual effects) - feature of the emergent order of higher levels of complexity
Dynamics of Radiation Belts - Salammbômodel
1. Radial diffusion only:
8
2100 MeV/G, equator, Kp =1.8
7
6
L5
plasmapause
4
3
2
Iteration number
(MeV-3s-3)
1025 1024 1023 1022 1021 1020
Empirical certainty: Prolonged southward IMF drives strong convection (westward Ey) and therefore storms. Large IMF Bs => intense storms.
Ring Current Formation – IMF Driver
Dynamics of Radiation Belts
Each new mission in the inner MS brings new insights (SAMPEX, CRRES)
Close correlation with storms / Large dynamic range: 10 to 10^4 (Li et al. 2019).
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 orbit
Association of MeV electrons with ULF waves / radial diffusion [Baker and Daglis, 2019]
Dynamics of Radiation Belts – Internal/external
Green and Kivelson, 2019 – Polar/HIST data 2019-2019
Jordanova et al. [2019]
Ring Current Dynamics
- RC sources (composition) / RC [a]symmetry
-RC formation: IMF driver
- RC formation: role of substorms
Ring Current Formation – IMF Driver
Dynamics of Radiation Belts
Location of the peak electron flux as a function of minimum Dst moves to lower L
O’Brien et al., JGR2019
Dynamics of Radiation Belts
Identify loss mechanisms Develop accurate energetic electron model
The classical ring concept
A very asymmetric 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 storms
Main issue: mechanism(s) that can efficiently accelerate and/or transport charged particles, leading to
-build-up of storm-time ring current
-enhanced fluxes of MeV radiation belt electrons.
Ring Current Sources / Composition Daglis, Magnetic Storms Monograph [2019]
Ring current asymmetry
Fig. 6 of Daglis et al. JGR2019
Ring Current Asymmetry & Ion Composition
Dynamics of Radiation Belts - Future Fully understand and specify radiation belt variability
(CRRES, Bernie Blake)
Dynamics of Radiation Belts - Future
Paulikas and Blake, 1979.
September 5, 2019 (Solar Min)
[Vassiliadis et al., JGR 2019]
Region P0: • Rapid (<1-day) response to magnetic clouds/ICMEs. • Characterizes L<4. • Representative events:
Dynamics of the Radiation Belts &
the Ring Current
Ioannis A. Daglis
Institute for Space Applications Athens
Dynamics of the near-space particle radiation environment
at the lower levels
Dynamicsቤተ መጻሕፍቲ ባይዱof Radiation Belts
Close association of storm-time enhancements of relativistic electron fluxes
with spacecraft failure.
Spacecraft operational anomalies, SAMPEX data [Baker & Daglis, 2019]
January 2019, May 2019: - Baker et al., GRL 2019; - Reeves et al., GRL 2019
May 4, 2019 (Solar Max)
Dynamics of Radiation Belts
O’Brien et al., JGR2019 SAMPEX, HEO-3 data / SAMNET, IMAGE
Dynamics of Radiation Belts
Close to GEO, ULF-wave enhanced radial diffusion is more important, pushing electrons inward and accelerating them.
Around L~5, VLF chorus waves accelerate electrons (microbursts) without displacing them in L.
MeV Electron Flux evolution after a Storm
Dst
Kp
300-500 keV 1.1-1.5 MeV
GEO
300-500 keV 1.1-1.5 MeV
GEO max
GPS max
T=0
GPS
1.22 MeV
equatorial flux
(L=4.2)
T=0
GEO max GPS max
8
7
1 MeV
6
L5
2. Plus chorus waves:
2100 MeV/G, equator, Kp =1.8
plasmapause
4
3 MeV
3
2
Iteration number
(MeV-3s-3)
1025 1024 1023 1022 1021 1020
Distribution Functions (MeV-3s-3)
Image courtesy Hannu Koskinen, FMI
Ring Current Dynamics
-RC sources (composition) / RC [a]symmetry
- RC formation: IMF driver - RC formation: role of substorms
Dynamics of Radiation Belts
Both ULF waves and microbursts are strongest during the main phase of storms, both progress to lower L during stronger magnetic activity, both continue to be active during the recovery phase of events, and both appear to be more active during intervals of high solar wind velocity.
Dynamics of Radiation Belts
Region P1: • Slow (2-3-day) response to hi-speed streams • Characteristic of GEO orbit • Prob. involves ULF waves • Representative study:
Substorms produce electrons with energies of 10s to 100s of keV, but 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 environment
Presumably, the ring current build-up and
the radiation belt enhancement,
being processes of a higher level of complexity, display properties not evident
Dynamics of the near-space particle radiation environment
In both cases, the most obvious driver
the magnetospheric substorm
appears to be insufficient
Dynamics of Radiation Belts
1.E+26 1.E+25 1.E+24 1.E+23 1.E+22 1.E+21 1.E+20
3
DLL and Chorus
DLL
Lpp
4
5
6
7
8
L
L=5.5: Values 100 times higher!
Varotsou et al.
Dynamics of Radiation Belts
Not simply a superposition, but a synergy of various lower-level processes (combined effect > sum of individual effects) - feature of the emergent order of higher levels of complexity
Dynamics of Radiation Belts - Salammbômodel
1. Radial diffusion only:
8
2100 MeV/G, equator, Kp =1.8
7
6
L5
plasmapause
4
3
2
Iteration number
(MeV-3s-3)
1025 1024 1023 1022 1021 1020
Empirical certainty: Prolonged southward IMF drives strong convection (westward Ey) and therefore storms. Large IMF Bs => intense storms.
Ring Current Formation – IMF Driver
Dynamics of Radiation Belts
Each new mission in the inner MS brings new insights (SAMPEX, CRRES)
Close correlation with storms / Large dynamic range: 10 to 10^4 (Li et al. 2019).
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 orbit
Association of MeV electrons with ULF waves / radial diffusion [Baker and Daglis, 2019]
Dynamics of Radiation Belts – Internal/external
Green and Kivelson, 2019 – Polar/HIST data 2019-2019
Jordanova et al. [2019]
Ring Current Dynamics
- RC sources (composition) / RC [a]symmetry
-RC formation: IMF driver
- RC formation: role of substorms
Ring Current Formation – IMF Driver
Dynamics of Radiation Belts
Location of the peak electron flux as a function of minimum Dst moves to lower L
O’Brien et al., JGR2019
Dynamics of Radiation Belts