of the Outer and Inner Radiation Belts during the Recent Solar Minimum, as Observed by Cluster and Double Star Natalia Ganushkina (1,2) , Iannis Dandouras (3), Yuri Shprits (4) , Jinbin Cao (5,6) (1) Finnish Meteorological Institute, Helsinki, Finland (2) University of Michigan, Ann Arbor, USA (3) IRAP (ex-CESR), CNRS / University of Toulouse, Toulouse, France (4) IGPP, University of California, Los Angeles, USA (5) Beijing University of Aeronautics and Astronautics, Beijing, China (6) State Key Laboratory of Space Weather, CSSAR, CAS, Beijing, China ILWS - 11 Science Workshop, Beijing, China, Aug-Sep 2011
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Locations of Boundaries of the Outer and Inner Radiation Belts during the Recent Solar Minimum, as Observed by Cluster and Double Star Natalia Ganushkina.
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Locations of Boundaries
of the Outer and Inner Radiation Belts
during the Recent Solar Minimum,
as Observed by Cluster and Double Star
Natalia Ganushkina (1,2) , Iannis Dandouras (3),
Yuri Shprits (4) , Jinbin Cao (5,6)
(1) Finnish Meteorological Institute, Helsinki, Finland
(2) University of Michigan, Ann Arbor, USA
(3) IRAP (ex-CESR), CNRS / University of Toulouse, Toulouse, France
(4) IGPP, University of California, Los Angeles, USA
(5) Beijing University of Aeronautics and Astronautics, Beijing, China
(6) State Key Laboratory of Space Weather, CSSAR, CAS, Beijing, China
To determine a boundary location:1. At a first instance, the spacecraft entry into a radiation belt appears as a substantial, homogeneous increase of count rate over all energy channels. 2.To more accurately define the boundary position, we then determine the first time moment when the Δc/s / Δt are the largest and same for all energy channels (sharpest gradient) and place a boundary there.
CLUSTER orbit at perigee on June 30, 2008
ORB
IRB
ORB
Boundaries of outer and inner radiation belts as observed by Cluster CIS at different orbits
B3 B4
Inner RBOuter RB Outer RB
B1 B2 B5 B6
ORB
ORB IRB
Example of boundaries’ locations at Double Star
B2 B3 B0 B4 B5
Outer RB Inner Outer RBInner
Locations of Rad-Belt boundaries for all events, MLT distribution (Cluster-CIS data): April 2007 - June 2009
B1 and B6:outer boundary of outer RB
B2 and B5:inner boundary of outer RB
B3 and B4:outer boundary of inner RB
Ganushkina, Dandouras, et al., JGR, in press, 2011
Locations of boundaries for all events with activity indices
B1 and B6:outer boundary of outer RB
B2 and B5:inner boundary of outer RB
B3 and B4:outer boundary of inner RB
Dst: moderate, no change
Kp and AE: decrease
Zoom
Locations of boundaries for all events with SW parameters
B1 and B6:outer boundary of outer RB
B2 and B5:inner boundary of outer RB
B3 and B4:outer boundary of inner RB
Running Average
Psw: no ave. change
Vsw: decrease
Dips of outer RB to lower L shells
Zoom on Outer RB boundary dip
Outer boundary of outer RB:- comes closer to Earth L=4- then moves tailward L=6
Time scale: 50 days
Before boundary dip:- Vsw from 430 to 540 km/sec- Kp to 5- Dst drop to -28 nT- AE to 700 nT- 2 peaks in Psw, 8 and 5 nPa
After boundary dip:- Vsw to 650 km/s- Kp to 5- Dst drop to -50 nT- AE to 800 nT- Psw at 3 nPa
Locations and width of slot region
slot widening: during: * low Vsw * low AE
Locations of boundaries Observed at Double Star
B2 and B5:inner boundary of outer RB
B3 and B4:outer boundary of inner RB
B0:Inner boundary of inner RB
SummaryDuring the period between April 2007 and June 2009 Cluster was deep in the
radiation belts, coming to Earth at its perigee as close as L = 2.
During that period: Psw, Dst no change, Vsw decrease, Kp and AE decrease.
Dips of outer boundary of outer RB: comes closer to Earth at L=4,
then moves tailward at L=6. Before dip: peaks in Psw.
After boundary dip: Vsw, Kp, AE increase, Dst drop, Psw no change.
Always peaks in Psw right before the flux drop out.
Slot region widening (from 1.5 to 3 RE) during low activity,
when Vsw and AE decrease:
consistent with weaker inward radial diffusion,
and also consistent with weaker local acceleration.
Boundaries determined from background measurements provide additional