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Evolutionary Characteristics of Magnetic Helicity Injection through Active Regions. Hyewon Jeong, Jongchul Chae Seoul National University. Purpose. How much helicity is supplied through active regions? - PowerPoint PPT Presentation
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Evolutionary Characteristics of Magnetic Helicity Injection through Active Regions
Hyewon Jeong, Jongchul Chae
Seoul National University
Purpose
How much helicity is supplied through active regions?
Does the helicity injection in an active region occurs intensively during a specific period or steadily through all of its lifetime?
Magnetic Helicity Magnetic helicity Sum of linking numbers over all pairs of closed field line
s in a given volume
xB dAH 3
v Pr xdPBAAH 3)()(
Relative magnetic helicityRelative magnetic helicity Magnetic helicity relative to the Magnetic helicity relative to the
helicity of potential field with the helicity of potential field with the same magnetic flux at the photosame magnetic flux at the photospheric boundaryspheric boundary
Method (Chae’s method)
Helicity transfer equation
s nPt dS)BA(u
dt
dΗ2
Apparent horizontal velocity of field line footpoint :
( LCT method) Normal component of photospheric magn
etic field : (line-of-sight magnetogram data) Vector potential for : (Fourier Transform method)
tu
nB
PAnB
Data and application
line-of-sight magnetogram data (SoHO/MDI)
96min cadence
calculation for about 5 days away from the limb
6 active regions
AR 10696
1st rotation
2nd rotation
AR 10696
AR 10365
1st rotation
2nd rotation
AR 10365
Summary
Active Regions(latitude, degree)
Helicity during the early phase[Mx2/5day]
Final Total flux [Mx]
Differential rotation
contribution [Mx2/5day]
AR 10696 (+8.16) -21.0x1042 3.49x1022 -0.48x1042
AR 10365 (-7.34) 8.40x1042 3.61x1022 0.48x1042
AR 8100 (-20.39) -13.5x1042 3.83x1022 1.3x1042
AR 10656 (-13.68) -43.5x1042 6.20x1022 2.6x1042
AR 7978 (-9.93) -2.45x1042 2.09x1022 0.22x1042
AR 10381 (-18.66) -1.75x1042 1.41x1022 0.075x1042
Conclusion
Magnetic helicity is supplied intensively during the growth of active regions or during flux emergence.
The range of the amount of helicity injected :
]/5dayMx101075.1 24242 [ 43.5 ~ The maximum helicity injection rate measured :
/h]Mx[ 107 241