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Stream interface slope near 1 AU and the configuration of the
heliospheric current sheet at 2.5 solar radii
K.D.C. Simunac
STEREO SWG
October 2009
Introduction
“… stream interfaces are offset from, but are aligned roughly parallel to, the heliospheric current sheet…because both arise from basically the same geometry back at the Sun”
Gosling and Pizzo, Formation and Evolution of Corotating Interaction Regions and Their Three Dimensional Structure, Space Science Reviews 89: 21 - 52, 1999.
Stream Interfaces:Quick Review
• The boundary marking a transition from slow to fast solar wind
• Speed increases
• Density drops
• Temperature increases
• Flow shears observedFigure 1 from Pizzo 1978.
Stream Interface: Example 1
1 hour averaged data from STEREO-A/
PLASTIC
28 June - 4 July, 2007
Bulk Speed [km/s]
Proton Density [cm-3]
Thermal Speed [km/s]
East/West Flow
[degrees]
North/South Flow
[degrees]
250
400
550
700
06/28/07 06/30/07 07/02/07 07/04/07 07/06/07
0
15
30
45
06/28/07 06/30/07 07/02/07 07/04/07 07/06/07
0
25
50
75
100
06/28/07 06/30/07 07/02/07 07/04/07 07/06/07
-12
-6
0
6
12
06/28/07 06/30/07 07/02/07 07/04/07 07/06/07
-8
-4
0
4
8
06/28/07 06/30/07 07/02/07 07/04/07 07/06/07
1
Lee 2000:Stream Interface Slope
“… the ratio of the N-S component to the E-W component of the transverse flow is -(e • n)/(e • n).”
Stream Interface 130 June 2007 06:48 to 07:09 UT
1 minute data from STEREO-A/
PLASTIC
1 minute averaged data
from STEREO-A/ IMPACT
-10
-5
0
5
10
30-Jun-200700:00
30-Jun-200706:00
30-Jun-200712:00
30-Jun-200718:00
01-Jul-200700:00
-10
-5
0
5
10
30-Jun-200700:00
30-Jun-200706:00
30-Jun-200712:00
30-Jun-200718:00
01-Jul-200700:00
250
350
450
550
30-Jun-200700:00
30-Jun-200706:00
30-Jun-200712:00
30-Jun-200718:00
01-Jul-200700:00
Bulk Speed [km/s]
East/West Flow
[degrees]
North/South Flow
[degrees]
B_R/B
-1.5
0
1.5
30-Jun-200700:00
30-Jun-200706:00
30-Jun-200712:00
30-Jun-200718:00
01-Jul-200700:00
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Example 1
GONG line-of-sight ecliptic plane field model
Red: B_R < 0
Green: B_R > 0
∆East/West = -2.3º - 2.5º = -4.8º
∆North/South = 3.1º - 4.3º = -1.2º
slope = 0.25
Stream Interface 2
1 hour averaged data from
STEREO-A/ PLASTIC
28 June - 6 July, 2007
Bulk Speed [km/s]
Proton Density [cm-3]
Thermal Speed [km/s]
East/West Flow
[degrees]
North/South Flow
[degrees]
250
400
550
700
06/28/07 06/30/07 07/02/07 07/04/07 07/06/07
0
15
30
45
06/28/07 06/30/07 07/02/07 07/04/07 07/06/07
0
25
50
75
100
06/28/07 06/30/07 07/02/07 07/04/07 07/06/07
-12
-6
0
6
12
06/28/07 06/30/07 07/02/07 07/04/07 07/06/07
-8
-4
0
4
8
06/28/07 06/30/07 07/02/07 07/04/07 07/06/07
1 2
Stream Interface 24 July 2007 13:45 to 13:53 UT
1 minute data from STEREO-A/
PLASTIC
1 minute averaged data
from STEREO-A/ IMPACT
-10
-5
0
5
10
04-Jul-200700:00
04-Jul-200706:00
04-Jul-200712:00
04-Jul-200718:00
05-Jul-200700:00
-10
-5
0
5
10
04-Jul-200700:00
04-Jul-200706:00
04-Jul-200712:00
04-Jul-200718:00
05-Jul-200700:00
Bulk Speed [km/s]
East/West Flow
[degrees]
North/South Flow
[degrees]
B_R/B
275
375
475
575
04-Jul-200700:00
04-Jul-200706:00
04-Jul-200712:00
04-Jul-200718:00
05-Jul-200700:00
-1.5
0
1.5
04-Jul-200700:00
04-Jul-200706:00
04-Jul-200712:00
04-Jul-200718:00
05-Jul-200700:00
Example 2
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
∆East/West = -5.2º - 1.4º = -6.6º ∆North/South = -1.3º - (-0.7º) = -0.6 slope = 0.09
Example 3
1 hour averaged data from
STEREO-A/ PLASTIC
4 - 13 July, 2007
-8
-4
0
4
8
07/04/07 07/06/07 07/08/07 07/10/07 07/12/07
-12
-6
0
6
12
07/04/07 07/06/07 07/08/07 07/10/07 07/12/07
0
25
50
75
100
07/04/07 07/06/07 07/08/07 07/10/07 07/12/07
0
15
30
45
07/04/07 07/06/07 07/08/07 07/10/07 07/12/07
250
400
550
700
07/04/2007 07/06/2007 07/08/2007 07/10/2007 07/12/2007
Bulk Speed [km/s]
Proton Density [cm-3]
Thermal Speed [km/s]
East/West Flow
[degrees]
North/South Flow
[degrees]
2
3
Stream Interface 311 July 2007 13:03 to 13:13 UT
1 minute data from STEREO-A/
PLASTIC
1 minute averaged data
from STEREO-A/ IMPACT
-1.5
0
1.5
11-Jul-200700:00
11-Jul-200706:00
11-Jul-200712:00
11-Jul-200718:00
12-Jul-200700:00
-10
-5
0
5
10
11-Jul-200700:00
11-Jul-200706:00
11-Jul-200712:00
11-Jul-200718:00
12-Jul-200700:00
-10
-5
0
5
10
11-Jul-200700:00
11-Jul-200706:00
11-Jul-200712:00
11-Jul-200718:00
12-Jul-200700:00
250
450
650
11-Jul-200700:00
11-Jul-200706:00
11-Jul-200712:00
11-Jul-200718:00
12-Jul-200700:00
Bulk Speed [km/s]
East/West Flow
[degrees]
North/South Flow
[degrees]
B_R/B
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Example 3∆East/West = -6.2º - 1.3º = -7.5º ∆North/South = -3.5º - (-7.8º) = 4.3 slope = -0.57
All 3 Examples and GONG Model
All 3 Examples and WSO Model
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
WSO Radial 2.5 R_Sun model
All 3 Examples and ENLIL Model
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
ENLIL model 0.1 AU
All 3 Examples and ENLIL Model
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
ENLIL model 0.1 AU
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
ENLIL model 0.1 AU
All 3 Examples and Predictive Science Model
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Predictive Science B_R at 2.5 Solar Radii
All 3 Examples and Predictive Science Model for 1 AU
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Predictive Science B_R at 215 Solar Radii
Example 4 -- More Recent
1 hour averaged data from
STEREO-A/ PLASTIC
28 Sept. - 6 Oct., 2009
-10
-5
0
5
10
28-Sep-2009 30-Sep-2009 2-Oct-2009 4-Oct-2009 6-Oct-2009
-10
-5
0
5
10
28-Sep-2009 30-Sep-2009 2-Oct-2009 4-Oct-2009 6-Oct-2009
0
20
40
60
80
28-Sep-2009 30-Sep-2009 2-Oct-2009 4-Oct-2009 6-Oct-2009
0
10
20
30
40
28-Sep-2009 30-Sep-2009 2-Oct-2009 4-Oct-2009 6-Oct-2009
250
350
450
550
28-Sep-2009 30-Sep-2009 2-Oct-2009 4-Oct-2009 6-Oct-2009
Bulk Speed [km/s]
Proton Density [cm-3]
Thermal Speed [km/s]
East/West Flow
[degrees]
North/South Flow
[degrees]
Stream Interface 41 October 2009 15:34 to 15:40 UT
-10
-5
0
5
10
01-Oct-200900:00
01-Oct-200906:00
01-Oct-200912:00
01-Oct-200918:00
02-Oct-200900:00
-10
-5
0
5
10
01-Oct-200900:00
01-Oct-200906:00
01-Oct-200912:00
01-Oct-200918:00
02-Oct-200900:00
250
350
450
550
01-Oct-200900:00
01-Oct-200906:00
01-Oct-200912:00
01-Oct-200918:00
02-Oct-200900:00
Bulk Speed [km/s]
East/West Flow
[degrees]
North/South Flow
[degrees]
Example 4
∆East/West = -2.9º - 1.7º = -4.6º ∆North/South = 0.3º - 0.7º = -0.4º slope = 0.09
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Summary and QuestionsAfter looking at about 30 cases with 1 hour time resolution, I conclude that the interfaces observed in connection with current sheet crossings do seem to be roughly parallel to the current sheet…somewhere.
I have looked at just a few interfaces with the 1 minute resolution data, but results are so far consistent with 1 hour averaged data.
In some cases the north/south and east/west flow shears are not exactly cotemporaneous -- what does this mean? How should I deal with it?
When the stream interface does not closely follow a current sheet crossing, what should we expect?
Thank you.
• PLASTIC team
• IMPACT team
• GONG consortium
• WSO
• Predictive Science
• CCMC