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Chromospheric and Coronal
Magnetic Field Tracing
with IRIS and AIA
Markus J. Aschwanden Bart De Pontieu
(LMSAL)
http://www.lmsal.com/~aschwand/2015_IRIS_Aschwanden.ppt
IRIS Science Telecon, Feb 11, 2015
0.45 0.50 0.55 0.60
0.20
0.25
0.30
0.35
0
1 2
3 4 5
6
7 8 9 10
11 12
13
14 15 16 17
18 19 20
0.45 0.50 0.55 0.60
0.75
0.80
0.85
0.90
0 10 20 30 40Misalignment angle m (deg)
0
50
100
150
200
250
300 m=15.10
20140329_170500, EVENT=592, FRAME= 0 / 26, RUN=AIA_EUV_01
NOAA =12017
Hel.pos. =N11W32
FOV =0.20
[x1,x2] = 0.4134, 0.6134
[y1,y2] = 0.1954, 0.3954
wave,nsm1, = 6, 3
thresh0,2,nsig = 0.00, 0.01, 3.00
rmin,lmin,ngap = 15, 15, 0
ds,nh =0.0020, 10
dx_euv = 0.000625 Rsun
dx_mag = 0.001500 Rsun
nmag = 100 / 100
n_nlfff = 97
dprox,magwid = 5.000, 2.0
nloopw,qripple = 200, 0.50
nall,ngood,nf = 406/275/275
n1,n2,n3,n4,n5 =116/1/1/13/0
niter = 10 / 20/ 20
hmin,hmax =0.001, 0.050
nseg,mdim = 7, 2
nsmax = 200
da0 = 1.0
misalign = 15.1 deg
div-free = 9.2e-07
force-free = 4.8e-07
weight curr = 1.5e-01
qB_rebin = 1.035
qB_model = 1.233
qiso_corr = 2.467
E_P = 211.2 x 1030 erg
E_free = 1.5 x 1030 erg
E_NP/E_P = 1.007
CPU = 324.0 s Slide 1
Photospheric vs. Coronal Magnetic Field Measurement Methods
PHOT-NLFFF COR-NLFFF
Input: Photospheric 3D vectors Photospheric Bz magnetogram
(Bx,By,Bz) Coronal loop coordinates
[x(s),y(s)] or [x(s),y(s),z(s)]
Method: Force-free α-parameter Forward-fitting of approximate
optimization NLFFF solution for vertical
currents
Problems: Nonforcefree photophere Sparse loops near sunspots,
( preprocessing) false loop detection in moss areas,
Misalignment of coronal loops neglects horizontal currents
Computation time:
2-12 hrs/run 1-3 min/run
Slide 2
Photosphere
Chromosphere
Transition region
Corona
Non-forcefree
Forcefree
Bphot
Bphot
Bcor
Bcor
m
Misalignment angle
Observed loop and fitted field lineExtrapolated
field line
Lorentz force
Potential field: PFSS code (no free energy available for flares)
Non-Potential field: NLFFF codes (extrapolation ignores non-forcefree zones,
use vector-magnetograph LOS + transverse field,
but are misaligned to geometry of coronal loops)
(e.g. Wheatland et al. 2000; Wiegelmann 2004; Grad & Rubin 1958)
Coronal NLFFF: Forward-fitting of analytical NLFFF approximation
to coronal loops, transverse field is free parameter
and can minimize misalignment with coronal loops)
(Aschwanden 2013, Aschwanden, Sun, & Liu 2014)
Slide 3
COR-NLFFF with (3D) or without stereoscopy (2D loop coordinates)
Aschwanden et al. (2012)
Slide 4
Challenges:
-crossing loops
-data noise
-background confusion moss)
-saturation, pixel bleeding
-entrance filter diffraction pattern
OCCULT-2 Code:
Local curvature radius
provides guiding of
directional
changes in tracing a
curvi-linear structure Slide 5
Slide 6
Untwisted fields Twisted fields
Slide 7
# 12 2011-02-15T01:44:00 UT, RUN 1,2,3
1.0 1.5 2.0 2.5 3.0
0
500
1000
1500
2000
Pote
ntial E
po
t[10
30 e
rg]
qEpot=1.07
# 12 2011-02-15T01:44:00 UT, RUN 1,2,3
1.0 1.5 2.0 2.5 3.0
0
100
200
300
400
500
Fre
e E
fre
e [
10
30 e
rg] qEfree= 0.22
qDE = 1.13PHOT-NLFFF: DE= 106COR-NLFFF: DE= 120+COR-NLFFF: DE= 120_ 10
# 37 2011-03-09T23:13:00 UT, RUN 1,2,3
22.5 23.0 23.5 24.0
0
500
1000
1500
2000
2500
3000
Po
tentia
l E
po
t[10
30 e
rg]
qEpot=1.10
# 37 2011-03-09T23:13:00 UT, RUN 1,2,3
22.5 23.0 23.5 24.0
0
200
400
600
800
Fre
e E
fre
e [10
30 e
rg] qEfree= 0.88
qDE = 3.54PHOT-NLFFF: DE= 75COR-NLFFF: DE= 268+COR-NLFFF: DE= 268_ 26
# 66 2011-09-06T22:12:00 UT, RUN 1,2,3
21.5 22.0 22.5 23.0
0
500
1000
1500
Pote
ntial E
po
t[10
30 e
rg]
qEpot=1.55
# 66 2011-09-06T22:12:00 UT, RUN 1,2,3
21.5 22.0 22.5 23.0
0
100
200
300
400
500
Fre
e E
fre
e [10
30 e
rg] qEfree= 0.58
qDE = 2.70PHOT-NLFFF: DE= 69COR-NLFFF: DE= 187+COR-NLFFF: DE= 187_ 9
# 67 2011-09-07T22:32:00 UT, RUN 1,2,3
22.0 22.5 23.0 23.5
0
200
400
600
800
1000
Pote
ntial E
po
t[10
30 e
rg]
qEpot=0.97
# 67 2011-09-07T22:32:00 UT, RUN 1,2,3
22.0 22.5 23.0 23.5
0
100
200
300
400
Fre
e E
fre
e [10
30 e
rg] qEfree= 1.97
qDE = 0.91PHOT-NLFFF: DE= 103COR-NLFFF: DE= 93+COR-NLFFF: DE= 93_ 7
#147 2012-03-07T00:02:00 UT, RUN 1,2,3
23.5 24.0 24.5 25.0 25.5
0
1000
2000
3000
4000
Pote
ntial E
po
t[10
30 e
rg]
qEpot=0.82
#147 2012-03-07T00:02:00 UT, RUN 1,2,3
23.5 24.0 24.5 25.0 25.5
0
500
1000
1500
2000
Fre
e E
fre
e [
10
30 e
rg] qEfree= 0.20
qDE = 0.79PHOT-NLFFF: DE= 350COR-NLFFF: DE= 275+COR-NLFFF: DE= 275_ 46
#148 2012-03-07T01:05:00 UT, RUN 1,2,3
0.5 1.0 1.5 2.0
0
1000
2000
3000
4000
Pote
ntial E
po
t[10
30 e
rg]
qEpot=0.84
#148 2012-03-07T01:05:00 UT, RUN 1,2,3
0.5 1.0 1.5 2.0
0
500
1000
1500
Fre
e E
fre
e [
10
30 e
rg] qEfree= 0.16
qDE = 14.32PHOT-NLFFF: DE= 14COR-NLFFF: DE= 200+COR-NLFFF: DE= 200_ 9
#220 2012-07-12T15:37:00 UT, RUN 1,2,3
15 16 17 18
0
2000
4000
6000
8000
Po
ten
tial E
po
t[10
30 e
rg] qEpot=0.99
#220 2012-07-12T15:37:00 UT, RUN 1,2,3
15 16 17 18
0
2000
4000
6000
8000
Fre
e E
fre
e [10
30 e
rg]
qEfree= 0.94qDE = 11.66
PHOT-NLFFF: DE= 120COR-NLFFF: DE=1399+COR-NLFFF: DE=1399_ 89
#344 2013-11-05T22:07:00 UT, RUN 1,2,3
21.5 22.0 22.5 23.0
0
1000
2000
3000
4000
5000
6000
Pote
ntial E
po
t[10
30 e
rg] qEpot=0.62
#344 2013-11-05T22:07:00 UT, RUN 1,2,3
21.5 22.0 22.5 23.0
0
200
400
600
800
Fre
e E
fre
e [10
30 e
rg]
qEfree= 0.19
qDE = 3.10
PHOT-NLFFF: DE= 88
COR-NLFFF: DE= 273+COR-NLFFF: DE= 273_ 66
#349 2013-11-08T04:20:00 UT, RUN 1,2,3
3.5 4.0 4.5 5.0
0
1000
2000
3000
4000
5000
6000
Pote
ntial E
po
t[10
30 e
rg] qEpot=1.61
#349 2013-11-08T04:20:00 UT, RUN 1,2,3
3.5 4.0 4.5 5.0
0
200
400
600
800
Fre
e E
fre
e [10
30 e
rg]
qEfree= 0.82
qDE = 3.51
PHOT-NLFFF: DE= 72
COR-NLFFF: DE= 252+COR-NLFFF: DE= 252_ 29
#351 2013-11-10T05:08:00 UT, RUN 1,2,3
4.5 5.0 5.5 6.0
0
1000
2000
3000
4000
Pote
ntial E
po
t[10
30 e
rg] qEpot=1.17
#351 2013-11-10T05:08:00 UT, RUN 1,2,3
4.5 5.0 5.5 6.0
0
200
400
600
800
Fre
e E
fre
e [1
03
0 e
rg]
qEfree= 0.53qDE = 4.55
PHOT-NLFFF: DE= 55COR-NLFFF: DE= 254+COR-NLFFF: DE= 254_ 51
#384 2014-01-07T18:04:00 UT, RUN 1,2,3
17.5 18.0 18.5 19.0 19.5
0
2000
4000
6000
8000
10000
Pote
ntia
l E
pot[1
03
0 e
rg] qEpot=0.64
#384 2014-01-07T18:04:00 UT, RUN 1,2,3
17.5 18.0 18.5 19.0 19.5
0
500
1000
1500
2000
2500
Fre
e E
fre
e [10
30 e
rg]
qEfree= 0.59qDE = 1.78
PHOT-NLFFF: DE= 164COR-NLFFF: DE= 292+COR-NLFFF: DE= 292_ 74
Comparison of time evolution PHOT-NLFFF vs. COR-NLFFF results
Slide 8
NSO IBIS G-band
Slide 9
AIA_EUV: 211 A
Automated Tracing of Coronal Loop Structures
Slide 10
AIA_UV: 304 A
IRIS_UV: 2796 A
Automated Tracing of Chromospheric Structures
Slide 11
0.45 0.50 0.55 0.60
0.20
0.25
0.30
0.35
0
1 2
3 4 5
6
7 8 9 10
11 12
13
14 15 16 17
18 19 20
0.45 0.50 0.55 0.60
0.75
0.80
0.85
0.90
0 10 20 30 40Misalignment angle m (deg)
0
50
100
150
200
250
300 m=15.10
20140329_170500, EVENT=592, FRAME= 0 / 26, RUN=AIA_EUV_01
NOAA =12017
Hel.pos. =N11W32
FOV =0.20
[x1,x2] = 0.4134, 0.6134
[y1,y2] = 0.1954, 0.3954
wave,nsm1, = 6, 3
thresh0,2,nsig = 0.00, 0.01, 3.00
rmin,lmin,ngap = 15, 15, 0
ds,nh =0.0020, 10
dx_euv = 0.000625 Rsun
dx_mag = 0.001500 Rsun
nmag = 100 / 100
n_nlfff = 97
dprox,magwid = 5.000, 2.0
nloopw,qripple = 200, 0.50
nall,ngood,nf = 406/275/275
n1,n2,n3,n4,n5 =116/1/1/13/0
niter = 10 / 20/ 20
hmin,hmax =0.001, 0.050
nseg,mdim = 7, 2
nsmax = 200
da0 = 1.0
misalign = 15.1 deg
div-free = 9.2e-07
force-free = 4.8e-07
weight curr = 1.5e-01
qB_rebin = 1.035
qB_model = 1.233
qiso_corr = 2.467
E_P = 211.2 x 1030 erg
E_free = 1.5 x 1030 erg
E_NP/E_P = 1.007
CPU = 324.0 s
0.45 0.50 0.55 0.60
0.20
0.25
0.30
0.35
0
1
2 3 4 5
6
7 8 9
10 11
12 13 14 15 16 17
18
19
20
0.45 0.50 0.55 0.60
0.75
0.80
0.85
0.90
0 10 20 30 40Misalignment angle m (deg)
0
20
40
60
80
100
120 m=14.90
20140329_182300, EVENT=592, FRAME=26 / 26, RUN=AIA_UV_05
NOAA =12017
Hel.pos. =N11W32
FOV =0.20
[x1,x2] = 0.4257, 0.6257
[y1,y2] = 0.1954, 0.3954
wave,nsm1, = 2, 3
thresh0,2,nsig = 0.00, 0.05, 3.00
rmin,lmin,ngap = 15, 10, 0
ds,nh =0.0020, 10
dx_euv = 0.000634 Rsun
dx_mag = 0.001500 Rsun
nmag = 100 / 100
n_nlfff = 97
dprox,magwid = 5.000, 2.0
nloopw,qripple = 200, 0.50
nall,ngood,nf = 204/102/102
n1,n2,n3,n4,n5 =78/0/0/24/0
niter = 10 / 20/ 20
hmin,hmax =0.001, 0.200
nseg,mdim = 7, 2
nsmax = 200
da0 = 1.0
misalign = 14.9 deg
div-free = 7.2e-07
force-free = 6.4e-05
weight curr = 7.7e-01
qB_rebin = 1.034
qB_model = 1.180
qiso_corr = 2.467
E_P = 197.2 x 1030 erg
E_free = 7.6 x 1030 erg
E_NP/E_P = 1.038
CPU = 134.7 s
Non-linear Force Free Field (COR-NLFFF) before and after flare
Slide 12
AIA_UV: 304 A AIA_EUV: 211 A
IRIS_UV: 2796 A
20140329_175300
Free energy
HMI
17.2 17.4 17.6 17.8 18.0 18.2 18.4
0
10
20
30
40
Efr
ee [
10
30 e
rg] AIA_UV
AIA_EUVIRIS_UV
17.2 17.4 17.6 17.8 18.0 18.2 18.4Time [hrs]
10-7
10-6
10-5
10-4
GO
ES
flu
x [
10
30 e
rg]
Slide 13
17.2 17.4 17.6 17.8 18.0 18.2 18.4Time [hrs of day 2014-03-29]
0
10
20
30
Efr
ee [10
30 e
rg]
AIA_EUV: 094,131,171,193,211,335 A
17.2 17.4 17.6 17.8 18.0 18.2 18.4Time [hrs of day 2014-03-29]
0
10
20
30
40
Efr
ee [10
30 e
rg]
AIA_UV: 304,1600 A
17.2 17.4 17.6 17.8 18.0 18.2 18.4Time [hrs of day 2014-03-29]
0
10
20
30
40
Efr
ee [10
30 e
rg]
IRIS_UV: 1400,2832,2796 A
17.2 17.4 17.6 17.8 18.0 18.2 18.4Time [hrs of day 2014-03-29]
10-7
10-6
10-5
10-4
10-3
GO
ES
flu
x [1
03
0 e
rg]
X1.0
Time evolution
of free energy:
GOES 1-8 A flux
& time derivative
Coronal (AIA-EUV)
Chromospheric (AIA-UV)
Chromospheric (IRIS)
Slide 14
Conclusions:
(1)The evolution of the free magnetic energy during the
2014 Mar 29 flare reaches a peak value of
Efree=(26±5) 1030 erg
and shows a step-wise decrease after the flare by
ΔEfree=(19±2) 1030 erg
(2)The evolution of the free energy is measured with the
COR-NLFFF method consistently from coronal loop
tracing (AIA EUV: 94, 131, 171, 193, 211, 335 A),
as well as from chromospheric tracing of magnetically
aligned structures (AIA UV: 304 A He II, 1600 A C IV,
IRIS 1400 A (C II, Si IV), 2832, 2796 A (Mg II).
(3)IRIS SJI images (with 4 times higher resolution than AIA)
are very useful to constrain the non-potential magnetic
field and the dissipated magnetic energy during flares.
http://www.lmsal.com/~aschwand/2015_IRIS_Aschwanden.ppt Slide 15