The CGEM Lorentz Force Data from HMI Vector FieldXudong Sun* (xudong@sun.stanford.edu) and the CGEM Team1

1 G. H. Fisher^ (PI), J. T. Hoeksema*, M. L. DeRosa+, W. P. Abbett^, D. J. Bercik^, M. C.-M. Cheung+, K. Hayashi*,M. D. Kazachenko^, Y. Liu*, B. J. Lynch^, A. A. Norton*, A. Sainz Dalda*, B. T. Welsch^

^UC Berkeley, *Stanford University, +LMSAL

Lorentz Force on Solar Plasma• The total Lorentz force acting on a plasma bulk at and above the solar photosphere can be written as a surface integral of the photosphericfield (Hudson et al. 2008, Fisher et al. 2012), e.g. Fz ∝ ∑(Bh

2-Bz2)

• Recent observations confirm photospheric field changes (e.g. Sun et al. 2012), resulting in a Lorentz force change (Fig. 1).• Such changes have been related to an impulse that launches CMEs, or an angular impulse that slows down sunspot rotation (Wang et al. 2014). They could be used to diagnose the eruption dynamics.

The CGEM Data Product: cgem.Lorentz• CGEM (Coronal Global Evolutionary Model) is a LWS strategic capability project (PI: G. H. Fisher) that aims to develop a new coronal model driven with photospheric magnetic field observations to better understand the coronal dynamics.• The Lorentz force data based on HMI vector field is CGEM’sfirst deliverable (documentation available in Sun et al. 2014).• We utilize the Space-weather HMI Active Region Patch (SHARP; Bobra et al. 2014) vector data (Hoeksema et al. 2014) to compute the Lorentz force in active regions every 12 minutes.• They are available now as a JSOC data series (cgem.Lorentz) at HMI JSOC website jsoc.stanford.edu (Fig. 2).• Data consist of: i) integrated Lorentz force as indices, on the whole patch and strong-field pixels only (Table 1); ii) Fz maps showing the force at each pixel (Fig. 3).

Fig 1 | Magnetic field change during flares. The initial field, Bi, becomes more inclined after the flare, Bf. Such changes result in larger Bh, thus an increase of Fz (adapted from Hudson et al. 2008, courtesy B.T. Welsch).

Preliminary Survey of Major Flares• A preliminary survey on Fz during major flares shows a variety of evolution profiles, possibly related to different magnetic topology.

Usage and Uncertainty

• Values differenced during eruptions are generally more meaningful.• Orbital-velocity related periodic signal is large; a longitudinal dependence seems to be present in Fx and Fz (Fig. 5).• SHARPs can be much larger than the flaring region, containing multiple ARs. Data need to be interpreted with care.

Fig 3 | Maps of Fz. (a) Vector field from central part of SHARP number 377 (NOAA AR 11158) at 2011-02-15T01:36, just before an X-2 class flare. Weak field is masked out and shown as white. (b) Vertical force Fzmap at 01:36, showing value integrated over the area of each pixel. (c) Difference of Fz between 02:36 (post-flare) and 01:36 (pre-flare).

Fig 4 | Temporal evolution of Fz for 24 major flares during 2010-2014. Events above M-5 and within 40-deg longitude are included. For each event, four hours of data are centered at the soft X-ray peak time. Only strong-field pixels are included. Most SHARPs are large compared to the flaring region. Integrating over the flaring region only generally yields more pronounced changes.

Fig 2 | Screen captures from HMI JSOC website. “RecordSelect” tab and keywords T_REC, TOTFX1, and TOTFZ1 are highlighted. Twenty records for SHARP number 377 (NOAA AR 11158) are selected with query: cgem.Lorentz[377][2011.02.15_00:00/4h]. One may also query on NOAA AR numbers.

Reference

32 33 34 35 36 37

−22

−21

−20

−19

−18

CEA X [deg]

CE

A Y

[deg

]

(a)

B

[×103 G]−2 −1 0 1 2

32 33 34 35 36 37

CEA X [deg]

(b)

Fz

[×1020 dyne]−2 −1 0 1 2

32 33 34 35 36 37

CEA X [deg]

(c)

δ Fz

[×1020 dyne]−2 −1 0 1 2

Fig 5 | Five-day evolution of AR 11158. Three keywords TOTFX1, TOTFY1, TOTFZ1 are plotted (strong-field pixels only). Periodic signal from the orbital velocity and a longitudinal dependence are much larger than the flare signal.

Bobra, M.G., Sun, X., Hoeksema, J.T., et al., 2014, SoPh, in pressFisher, G.H., Bercik, D.J., Welsch, B.T., & Hudson, H.S., 2012, SoPh, 277, 59Hoeksema, J.T., Liu, Y., Hayashi, K., et al., 2014, SoPh, in pressHudson, H.S., Fisher, G.H., & Welsch, B.T., 2008, ASPCS, 383, 221Sun, X., Hoeksema, J.T., Liu, Y., et al., 2012, ApJ, 748, 77Sun, X. for the CGEM team, 2014, arXiv, 1405.7353Wang, S., Liu, C., Deng, N., & Wang, H., 2014, ApJL, 782, L31Wang, S., Liu, C., Liu, R., et al., 2012, ApJL, 745, L17

−1.1−0.9

−0.7

−0.5

−0.3−0.1

Fz

[1023

dyn

e]

00 #0377 2011−02−13T17:38 M6.6

AR1158

−1.6−1.4

−1.2

−1.0

−0.8−0.6

01 #0377 2011−02−15T01:56 X2.2

AR1158

−1.60−1.55

−1.50

−1.45

−1.40−1.35

02 #0401 2011−03−09T23:23 X1.5

AR1166

−2.85−2.75

−2.65

−2.55

−2.45−2.35

03 #0750 2011−07−30T02:09 M9.3

AR1261

−1.75−1.70

−1.65

−1.60

−1.55−1.50

Fz

[1023

dyn

e]

04 #0750 2011−08−03T13:48 M6.0

AR1261

−1.47−1.41

−1.35

−1.29

−1.23−1.17

05 #0833 2011−09−06T01:50 M5.3

AR1283

−1.55−1.50

−1.45

−1.40

−1.35−1.30

06 #0833 2011−09−06T22:20 X2.1

AR1283

−2.47−2.41

−2.35

−2.29

−2.23−2.17

07 #0833 2011−09−07T22:38 X1.8

AR1283

−5.2−5.0

−4.8

−4.6

−4.4−4.2

Fz

[1023

dyn

e]

08 #1449 2012−03−07T00:24 X5.4

AR1429

−5.08−4.84

−4.60

−4.36

−4.12−3.88

09 #1449 2012−03−07T01:14 X1.3

AR1430

−4.8−4.6

−4.4

−4.2

−4.0−3.8

10 #1449 2012−03−09T03:53 M6.3

AR1429

−6.8−6.6

−6.4

−6.2

−6.0−5.8

11 #1449 2012−03−10T17:44 M8.4

AR1429

−3.1−3.0

−2.9

−2.8

−2.7−2.6

Fz

[1023

dyn

e]

12 #1638 2012−05−10T04:18 M5.7

AR1476

−2.8−2.6

−2.4

−2.2

−2.0−1.8

13 #1807 2012−07−02T10:52 M5.6

AR1515

−3.9−3.7

−3.5

−3.3

−3.1−2.9

14 #1807 2012−07−04T09:55 M5.3

AR1515

−9.5−9.0

−8.5

−8.0

−7.5−7.0

15 #1834 2012−07−12T16:49 X1.4

AR1520

−2.8−2.6

−2.4

−2.2

−2.0−1.8

Fz

[1023

dyn

e]

16 #2635 2013−04−11T07:16 M6.5

AR1719

−3.85−3.75

−3.65

−3.55

−3.45−3.35

17 #3295 2013−10−24T00:30 M9.3

AR1877

−3.25−3.13

−3.01

−2.89

−2.77−2.65

18 #3321 2013−11−01T19:53 M6.3

AR1884

−3.55−3.45

−3.35

−3.25

−3.15−3.05

19 #3321 2013−11−03T05:22 M5.0

AR1884

−2 −1 0 1 2−8.5−8.3

−8.1

−7.9

−7.7−7.5

Time [hour]

Fz

[1023

dyn

e]

20 #3341 2013−11−05T22:12 X3.3

AR1890

−2 −1 0 1 2−4.0−3.8

−3.6

−3.4

−3.2−3.0

Time [hour]

21 #3341 2013−11−08T04:26 X1.1

AR1890

−2 −1 0 1 2−4.6−4.4

−4.2

−4.0

−3.8−3.6

Time [hour]

22 #3341 2013−11−10T05:14 X1.1

AR1890

−2 −1 0 1 2−6.25−5.75

−5.25

−4.75

−4.25−3.75

Time [hour]

23 #3563 2014−01−07T10:13 M7.2

AR1944

arXiv JSOC