Mapping the sub-oval proton auroras
into the magnetosphere
A. G. Yahnin and T. A. Yahnina
Polar Geophysical Institute, Apatity, Russia
Plasma Physics in the Solar System, SRI, Moscow, 6-10 February 2012
Proton aurora from the IMAGE spacecraft
proton H
Lyman 
photon
N2
collision
charge exchange
The FUV SI12 instrument onboard
the IMAGE spacecraft was capable
to observe the “proton aurora” - the
luminosity in the Doppler shifted
Lyman Hα line at 121.82 nm. This
emission is produced by
precipitation of magnetospheric
protons after charge exchange with
atmospheric constituents.
velocity
excited neutral H
The Doppler shift is due to motion
of the emitting neutral hydrogen.
emission
H atom
Courtesy of S. Mende
2
Proton aurora from the IMAGE spacecraft
Dayside sub-oval proton flashes
Hubert et al., GRL, 2003
Zhang et al., JGR, 2003
Fuselier et al., JGR, 2004
Sub-oval proton spots
Sub-oval proton arcs
Frey et al., JGR, 2004
Immel et al., GRL, 2002
Burch et al., JGR, 2002
Spasojevic et al., JGR,
2004
After H. Frey, Rev. Geophys., 2007
3
Relationship between sub-oval proton aurora and
EMIC/Pc1 waves
Day-side sub-oval proton flashes
Yahnina et al., JGR, 2008
Popova et al., GA, 2010
Zhang et al., JGR, 2008
Sub-oval proton arcs
Sub-oval proton spots
Yahnin et al., JGR, 2007
Yahnina & Yahnin, GA,
2012
Immel et al., GM, 2005
Yahnin et al., JGR, 2009
Spasojevic et al., GM, 2005
Yuan et al., GRL, 2010
4
Relationship between sub-oval proton aurora and
EMIC/Pc1 waves
Day-side sub-oval proton flashes
Pc1 bursts or Pc1
3
Sub-oval proton spots
“Monochromatic” Pc1
2
1
0
4
5
6
7
UT, h
8
Sub-oval proton arcs
IPDP or Pc1
9
10
Frequency, Hz
H-component
Frequency, Hz
4
4
3
2
1
0
15
16
16.5
UT, h
4
Frequency, Hz
15.5
3
2
1
0
18
19
20
UT, h
21
5
Mapping the sub-oval proton aurora relatively to
plasmapause
Mapping into the magnetosphere is, in particular, important for understanding
what is (are) the main parameter(s) controlling the regime of the IC instability
development (hot proton anisotropy, hot proton density, and cold plasma
density) in different conditions.
As to cold plasma, direct comparisons of sub-oval aurora with plasmasphere
are very scanty in spite of the IMAGE spacecraft carried a special instrument
(EUV imager) to observe the cold plasma distribution.
6
Mapping the sub-oval proton aurora relatively to
plasmapause
We used the plasmapause model by V. Pierrard from Belgian Institute for
Space Aeronomy; this model is available at http://www.spaceweather.eu.
In this model the plasmapause is suggested to form due to Lemaire’s physical
mechanism based on interchange instability (e.g., Lemaire and Gringauz,
1998).
7
Mapping the sub-oval proton aurora relatively to
plasmapause
Pierrard & Lemaire, GRL,
2004
Pierrard & Cabrera, Ann.
Geophys., 2005
Pierrard et al., JGR, 2007
Pierrard & Stegen, JGR, 2008
Numerical calculations based on the Lemaire’s theory and a Kp-dependent
magnetospheric electric field model satisfactorily reproduce plasmapause
observed with IMAGE EUV.
8
Event of 2 Sep 2004
1 Sept
20040902
PP 07:00 UT
12
2 Sept
3 Sept
proton spot
11 of 13 considered events demonstrate
that proton spots map into the vicinity of
plasmapause (L<0.5 RE).
18
4
2
2
00
4
06
This is one of “good” examples.
9
Event of 25 June 2003
24 Jun
20030625
PP 13:00 UT
12
25 Jun
26 Jun
proton spot
11 of 13 considered events demonstrate
that proton spots map into the vicinity of
plasmapause (L<0.5 RE).
6
4
2
This is one of “good” examples.
00
10
Event of 17July 2004
16 Jul
20030717
PP 12:30 UT
12
17 Jul
18 Jul
proton spot
11 of 13 considered events demonstrate
that proton spots map into the vicinity of
plasmapause (L<0.5 RE).
18
4
2
2
00
4
06
This is one of “good” examples.
11
Event of 3 Aug 2003
FUV
2 Aug
20020803
PP 19:30 UT
12
3 Aug
4 Aug
proton spot
11 of 13 considered events demonstrate
that proton spots map into the vicinity of
plasmapause (L<0.5 RE).
18
4
2
2
00
4
06
This is one of “good” examples.
12
Event of 26 Nov 2001
FUV
EUV
25 Nov
26 Nov
27 Nov
Frey et al., 2004
20011126
PP 08:00 UT
12
proton spot
“Bad” example: The spot maps well
inside modeled plasmapause.
18
4
2
2
00
4
06
However, EUV data show clear structure
of the outer plasmasphere.
Thus, location of the spot projection in
this case is also consistent with the cold
plasma gradient.
13
Event of 28 Feb 2001
27 Feb
20010228
PP 07:00 UT
12
28 Feb
29 Feb
proton spot
“Bad” example: The spot maps well
outside modeled plasmapause.
18
4
2
2
00
4
06
14
Conclusion
• Mapping of the proton aurora spots onto the
equatorial plane shows that the source of the
quasi-monochromatic EMIC emissions (Pc1)
tends to occur at the cold plasma gradients.
• This agrees with the theoretical prediction that
both low and very high values of the cold
plasma density reduce the increment of the
ion-cyclotron instability.
• Observations of proton aurora spots can be
used as an indicator of the plasmapause
location.
15
Night-to-morning side sub-oval proton aurora arc
(Poster #96)
IMAGE 10 November 00:50 UT
NOAA-16 orb 21317n
50
Proton flux
(cm2 sr s)-1
107
Jpr(max):
00:48:16 UT
03.47 MLT
50.04 CGLat
L=2.42
5
10
70
103
65
60
55
50
45
Corrected Geomagnetic Latitude, deg
18
NOAA-16
00
16
Night-side sub-oval proton aurora arc, LPEP and
plasmapause
10 November 2004 00 - 04 UT
Jpr max:
108
NOAA-17 orb 12366n
00:23:35 UT
22.61 MLT
50.53 CGLat (L=2.48)
106
104
102
20041110
Plasmapause
for 00 - 04 UT
Proton arc
12
LPEP
NOAA-16 orb 21317n
00:48:16 UT
03.47 MLT
50.04 CGLat (L=2.42)
106
104
102
NOAA-16 orb 21317s
01:16:18 UT
01.01 MLT
-51.08 CGLat (L=2.53)
106
Flux (cm2 sr s) -1
104
102
NOAA-16 orb 21317s
01:38:30 UT
16.72 MLT
-56.11 CGLat (L=3.22)
106
104
102
NOAA-15 orb 33756n
01:40:10 UT
17.07 MLT
-55.69 CGLat (L=3.15)
106
104
18
4
2
2
06
4
102
NOAA-16 orb 21318s
02:59:54 UT
00.99 MLT
-49.62 CGLat (L=2.38)
106
104
102
NOAA-16 orb 21319n
03:52:06 UT
13.64 MLT
52.44 CGLat (L=2.69)
106
104
102
NOAA-15 orb 33757s
04:10:30 UT
05.24 MLT
-50.12 CGLat (L=2.43)
106
104
102
00
70
45
50
55
60 60 65
Corrected Geomagnetic Latitude, deg
17
Thanks for your attention!
18