AC Foster 1 CJ Owen 1 AN Fazakerley 1 C Forsyth 1 E Lucek 2 H Rème 3 UCL Mullard Space Science Laboratory Surrey UK Imperial College London UK CNRS IRAP Toulouse France ID: 382492
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Slide1
Studying Solar Wind Magnetic Reconnection Events using the Cluster 4-point Measurement Capability
A.C. Foster
1, C.J. Owen1, A.N. Fazakerley1, C. Forsyth1 E. Lucek2, H. Rème3UCL, Mullard Space Science Laboratory, Surrey, UKImperial College, London, UKCNRS, IRAP, Toulouse, France
UCL DEPARTMENT OF SPACE & CLIMATE PHYSICS
MULLARD SPACE SCIENCE LABORATORYSlide2
Magnetic
Reconnection Observables
First study of solar wind reconnection made by Gosling, 2005.
Bifurcated current sheet
Magnetic field rotations over current sheets
Enhanced plasma jet / reconnection exhaust
Reconnection Exhaust
Reconnection Exhaust
Adapted from Gosling
, J.T. (2005)
Inflow
Inflow
Inflow
Inflow
Magnetic Field Lines
Current Sheet
A1
A2
B
BSlide3
Phan,T.D
(2006
)
Unconstrained
b
oundary
conditions
Multiple spacecraft observations
Time scales
≤ few hours
Length scales
~100s R
E
Different plasma conditions than frequently studied
(e.g. Magnetopause / magnetotail
)
Advantages in studying Reconnection in the Solar Wind
Earth
ACE
Cluster
Wind
Exhaust
To Sun
Jet
Jet
B
M
Solar Wind DirectionSlide4
Phan,T.D
(2006
)
13
12
11
10
9
5
0
-10
-5
20
0
-20
-40
-340
-350
-360
32
m
00
s
34
m
00
s
02
h
30m00s
|B| (nT)
B (nT) Ion Velocity (kms-1)
Magnetic rotation at current sheets
Previous study of reconnection event 02/02/2002
Data from Cluster 3 in GSE
Total --
X --
Y --
Z -- Slide5
Phan,T.D
(2006
)
13
12
11
10
9
5
0
-10
-5
20
0
-20
-40
-340
-350
-360
32
m
00
s
34
m
00
s
02
h
30m00s
|B| (nT)
B (nT) Ion Velocity (kms-1)
Magnetic rotation at current sheets
Previous study of reconnection event 02/02/2002
Data from Cluster 3 in GSE
Total --
X --
Y --
Z --
Using Cluster’s 4 point-measurement capability it was not possible to reproduce these results.
Small scale features (e.g. Ripples in the current sheets) in these reconnection events?Slide6
My study will initially look at the magnetic reconnection structures on a relatively small scale using the 4 Cluster spacecraft.
This is in order to test more detailed reconnection models: is it possible to predict the outflow conditions given the inflow conditions?
The extended study will look at the events on a larger scale using ACE and Wind.
Aim of ProjectSlide7
7
53
h
30
m
6
6
40
20
052
h30m53h00m54h00mUT|B| (nT)Ion Velocity Enhancement (km s-1)Total -- X --Y -- Z -- Reconnection Exhaust
Magnetic Field and Ion Velocity Enhancement (GSE)
Cluster 3
5
4
2
-2
18
16
14
12
B
(
nT
)
Density (
particles c
m-3)Slide8
7
53
h
30
m
6
6
40
20
052
h30m53h00m54h00mUT|B| (nT)Ion Velocity Enhancement (km s-1)Total -- X --Y -- Z -- Reconnection Exhaust
Magnetic Field and Ion Velocity Enhancement (GSE)
Cluster 3
5
4
2
-2
18
16
14
12
B
(
nT
)
Density (
particles c
m-3)
Inflow 1 speed = 48kms
-1
Inflow 2 speed = 42kms
-1
Average exhaust speed = 45kms
-1Slide9
Minimum Variance Technique
Results were consistent between spacecraft.
In all cases:
Normal direction vector taken as minimum variance direction
Current Sheet Orientation Determination
Sheet 1
Sheet 2
Earth
To the Sun
X-Line
Sheet 1
Sheet 2
Solar Wind DirectionSlide10
Sheet 1
Sheet 2
Earth
To the Sun
X-Line
Sheet 1
Sheet 2
Solar Wind Direction
X-line
Direction
Cross product of the normal direction vector of each current sheet
Point on plane – position that Cluster 3
encounters
sheet.
Right handed
system for each current sheet
Assumption
made:
Current sheets can be considered as flat planes
Current Sheet Co-ordinate System Determination Slide11
Average velocity lies between current sheets
Perpendicular to X-direction
Exhaust Velocity Determination
Sheet 1
Reconnection Exhaust
Sheet 2
X-Point
Cluster 3 trajectory through exhaust Slide12
Comparing the data to more detailed reconnection models
Looking at the small
scale features in these large scale structuresComparing the Cluster data with data from ACE and Wind which also saw the event.
Ongoing WorkSlide13
Baumjohann, W. (1997): Wolfgang
Baumjohann and Rudolf A. Treumann. Basics of Space Plasma Physics. Imperial College Press, 1997.
Priest, E. R. (1984): Priest, E. R. (1984), Solar Magneto-Hydrodynamics, Geophys. Astrophys.Monogr. Ser., Springer, New York.Gosling, J.T (2005): J.T. Gosling, R.M. Skoug, D.J. McComas, C.W. Smith, J. Geophys. Res. 110, A01107, 2005Phan, T. D. (2006): T. D. Phan, J. T. Gosling, M. S. Davis, R. M. Skoug, M. Øieroset, R. P. Lin, R. P. Lepping, D. J.McComas, C. W. Smith, H. Reme, and A. Balogh
. A magnetic reconnection X-line extending more than 390 Earth radii in the solar wind. Nature, 439:175–178, January 2006.
Gosling (2007): J. T. Gosling, S.
Eriksson,L
. M.
Blush,T
. D.
Phan,J. G. Luhmann,D. J. McComas,R. M. Skoug,M. H. Acuna,C. T. Russell, and K. D. Simunac. Five spacecraft observations of oppositely directed exhaust jets from a magnetic reconnection X-line extending > 4.26 106km in the solar wind at 1 AUReferences
UCL DEPARTMENT OF SPACE & CLIMATE PHYSICSMULLARD SPACE SCIENCE LABORATORYSlide14
UCL DEPARTMENT OF SPACE & CLIMATE PHYSICS
MULLARD SPACE SCIENCE LABORATORYSlide15
Minimum Variance AnalysisSlide16
Cluster ConfigurationSlide17
B
(
nT
)
C1
C2
C3
C4
UT
Total --
X --Y -- Z -- Reconnection Event Interval
Magnetic Field (GSE)
Max R = 0.92 (x)
Min R = 0.75 (y)
Max R = 0.99 (z)
Min R = 0.76 (y)
Max R = 0.94 (z)Min R = 0.77 (y)
Max R = 0.99 (x)Min R = 0.36 (y)Max R = 0.99 (z)Min R = 0.73 (y)Max R = 0.99 (y)
Min R = 0.58 (x)
4
0
-4
4
0
-4
4
0
-4
4
0
-4
52
m
00
s
52
m
30
s
53
m
00
s
53
m
30
s
54
m
00s
54
m
30
s
55
m
00
sSlide18
B
(
nT
)
C1
C2
C3
C4
UT
Total --
X --Y -- Z -- Reconnection Event Interval
Magnetic Field (GSE)
7
6
5
4
7
6
5
4
7
6
5
4
7
6
5
4
52
m
30
s53m00s
53
m
30
s
54
m
00
s
54
m
30
s