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

2

proton H

collisioncharge exchange

Lyman photon N2

velocity

excited neutral H

emission

H atom

Courtesy of S. Mende

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.

The Doppler shift is due to motion of the emitting neutral hydrogen.

Proton aurora from the IMAGE spacecraft

3After H. Frey, Rev. Geophys., 2007

Sub-oval proton spots

Frey et al., JGR, 2004

Dayside sub-oval proton flashes

Hubert et al., GRL, 2003

Zhang et al., JGR, 2003

Fuselier et al., JGR, 2004

Sub-oval proton arcs

Immel et al., GRL, 2002

Burch et al., JGR, 2002

Spasojevic et al., JGR, 2004

Proton aurora from the IMAGE spacecraft

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Day-side sub-oval proton flashes Yahnina et al., JGR, 2008Popova et al., GA, 2010Zhang et al., JGR, 2008

Sub-oval proton arcs

Immel et al., GM, 2005

Yahnin et al., JGR, 2009

Spasojevic et al., GM, 2005

Yuan et al., GRL, 2010

Sub-oval proton spots

Yahnin et al., JGR, 2007

Yahnina & Yahnin, GA,

2012

Relationship between sub-oval proton aurora and EMIC/Pc1 waves

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Day-side sub-oval proton flashesPc1 bursts or Pc1

Sub-oval proton arcsIPDP or Pc1

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1 8 1 9 2 0 2 1U T , h

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1 5 1 5 . 5 1 6 1 6 . 5

U T, h

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Relationship between sub-oval proton aurora and EMIC/Pc1 waves

Sub-oval proton spots

“Monochromatic” Pc1

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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.

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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).

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Pierrard & Lemaire, GRL, 2004

Pierrard & Cabrera, Ann. Geophys., 2005

Pierrard et al., JGR, 2007

Pierrard & Stegen, JGR, 2008

Mapping the sub-oval proton aurora relatively to plasmapause

Numerical calculations based on the Lemaire’s theory and a Kp-dependent magnetospheric electric field model satisfactorily reproduce plasmapause

observed with IMAGE EUV.

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Event of 2 Sep 2004

1 Sept 2 Sept 3 Sept

20040902PP 07:00 U T

proton spot

4 2

12

00

18 062 4

11 of 13 considered events demonstrate that proton spots map into the vicinity of plasmapause (L<0.5 RE).

This is one of “good” examples.

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24 Jun 25 Jun 26 Jun20030625PP 13:00 U T

proton spot

6 4 2

12

00

Event of 25 June 2003

11 of 13 considered events demonstrate that proton spots map into the vicinity of plasmapause (L<0.5 RE).

This is one of “good” examples.

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Event of 17July 2004

16 Jul 17 Jul 18 Jul

20030717PP 12:30 U T

proton spot

4 2

12

00

18 062 4

11 of 13 considered events demonstrate that proton spots map into the vicinity of plasmapause (L<0.5 RE).

This is one of “good” examples.

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2 Aug 3 Aug 4 Aug

Event of 3 Aug 2003FUV

11 of 13 considered events demonstrate that proton spots map into the vicinity of plasmapause (L<0.5 RE).

This is one of “good” examples.

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25 Nov 26 Nov 27 Nov

20011126PP 08:00 U T

proton spot

4 2

12

00

18 062 4

Frey et al., 2004

Event of 26 Nov 2001

“Bad” example: The spot maps well inside modeled plasmapause.

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.

FUV EUV

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27 Feb 28 Feb 29 Feb

20010228PP 07:00 U T

proton spot

4 2

12

00

18 062 4

“Bad” example: The spot maps well outside modeled plasmapause.

Event of 28 Feb 2001

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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.

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IMAGE 10 November 00:50 UT

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18

50

70

Night-to-morning side sub-oval proton aurora arc(Poster #96)

NOAA-16

6 5 6 0 5 5 5 0 4 5Corrected G eom agne tic La titude , deg

Pro

ton

flu

x(c

m2

sr

s)-1

10 7

10 5

10 3

N O AA-16 orb 21317n

Jpr(m ax):00:48:16 U T03.47 M LT50.04 C G Lat L=2.42

176070

Night-side sub-oval proton aurora arc, LPEP and plasmapause

20041110P lasm apausefor 00 - 04 U T

4 2

12

00

18 062 4

P roton arc

LPEP

Flu

x (c

m2

sr s

) -1

4 5 5 0 5 5 6 0 6 5C o r r e c t e d G e o m a g n e t i c L a t i t u d e , d e g

10 N ovem ber 2004 00 - 04 U T

NOAA-16 o rb 21317s 01:38:30 U T 16.72 M LT-56.11 C G Lat (L=3.22)

NOAA-16 o rb 21317s 01:16:18 U T 01.01 M LT-51.08 C G Lat (L=2.53)

NOAA-16 o rb 21319n 03:52:06 U T13.64 M LT52.44 C G Lat (L=2.69)

NOAA-15 o rb 33757s 04:10:30 U T 05.24 M LT-50.12 C G Lat (L=2.43)

NOAA-17 o rb 12366n00:23:35 U T22.61 M LT50.53 C G Lat (L=2.48)

NOAA-16 o rb 21317n00:48:16 U T03.47 M LT50.04 C G Lat (L=2.42)

NOAA-16 o rb 21318s 02:59:54 U T 00.99 M LT-49.62 C G Lat (L=2.38)

NOAA-15 o rb 33756n 01:40:10 U T 17.07 M LT-55.69 C G Lat (L=3.15)

Jpr m ax:10 8

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Thanks for your attention!