Magnetic Field Goals
– magnetic field & eruptive events
Yang Liu
Stanford University
HMI Science – 1 May 2003
Yang Liu/Magnetic Field
1
•
Sources and drivers of solar activity and disturbances.
•
Links between the internal processes and dynamics of the corona and
heliosphere.
•
Applications for space-weather forecasts.
HMI Science – 1 May 2003
Yang Liu/Magnetic Field
2
•
Sources and drivers of solar activity and disturbances (mechanisms of
flares, CMEs, and filament eruption).
–
Change of magnetic field during eruption of filaments.
–
Change of magnetic field during flares.
–
Change of magnetic field during CMEs.
–
Emergence of magnetic flux and solar transient events.
HMI Science – 1 May 2003
Yang Liu/Magnetic Field
3
•
Change of magnetic field during eruption of filaments.
HMI Science – 1 May 2003
Yang Liu/Magnetic Field
4
•
Change of magnetic field during flares.
u1
HMI Science – 1 May 2003
q1
Yang Liu/Magnetic Field
5
•
Change of magnetic field during CMEs.
Before CMEs
Li et al. (2002) used
Potential-Field
Source-Surface
model to detect
occurrence of CMEs.
After CMEs
HMI Science – 1 May 2003
Yang Liu/Magnetic Field
6
•
Emerging magnetic flux and solar eruptive events.
–
Emerging flux associated with flares, eruption of filament, CMEs.
HMI Science – 1 May 2003
Yang Liu/Magnetic Field
7
•
Sources and drivers of solar activity and disturbances (summary).
–
Magnetic field changes during transient events; emerging of magnetic flux associates
with ( causes?) solar eruptive events.
–
Need a method to quantitatively describe this change.
› Magnetic shear angle; Electric current; Source field; Others …
Need a method to describe variation of this change versus time.
Need to incorporate this information with further research, application for investigation
of mechanisms of solar eruption and for space weather forecast.
–
–
–
Data requirements.
Obs.
Accuracy
Spatial Res.
Temp. res.
cadence
interval
B_v
priority
2 arcsec
--
10min
6hour
B_los
priority
2arcsec
--
5min
6hour
EUV
--
priority
priority
2min
1hour
Coronal img
--
priority
priority
10min
1hour
Brightness
--
2arcsec
--
5min
6hour?
HMI Science – 1 May 2003
Yang Liu/Magnetic Field
8
•
Links between the internal processes and dynamics of the corona and
heliosphere.
–
–
–
Complexity and energetics of the solar corona (instability & energy buildup).
Relationship of small-scale and large-scale field.
Large-scale coronal field estimates.
HMI Science – 1 May 2003
Yang Liu/Magnetic Field
9
a. 86 active regions
with more than 3
major flares (Tian
& Liu, 2003);
b. 99 active regions
from Mees (
Canfield &
Pevstov, 1998);
c. 203 bipolar active
regions from
Huairou (Tian, et
al. 2001);
d. 22 bipolar active
regions with long
lifetime (at least
one rotation)
(Lepoz Fuentes,
et al., 2003)
HMI Science – 1 May 2003
Yang Liu/Magnetic Field
10
•
Relationship between small-scale and large-scale magnetic field.
–
–
To understand flares and CMEs;
To understand the role of active regions to large-scale field structure.
Wang, et al.
(2002)
HMI Science – 1 May 2003
Yang Liu/Magnetic Field
11
•
Relationship between small-scale and large-scale magnetic field (cont’)
Potential Field
Model
Force-free Field
Model
HMI Science – 1 May 2003
Yang Liu/Magnetic Field
12
•
Large-scale coronal field estimates (based on a Horizontal Current Current-Sheet
Source-Surface model (HCCSSS)).
HMI Science – 1 May 2003
Yang Liu/Magnetic Field
13
•
Links between the internal processes and dynamics of the corona and
heliosphere (summary).
–
Processes for energy & instability buildup still remain unknown. Two mechanisms, the
subphotospheric process or the photospheric shear motion, may in fact both work.
–
Observations show links between small-scale and large-scale fields, and also relates
with solar eruptive events.
–
Coronal modeling discovers two types of large-scale closed field, one of them, helmet
streamer, strongly associates with halo-CMEs.
–
Need a way to link those stuffs.
› Helicity; magnetic topology; …
–
Data requirements:
› Same as previous one.
HMI Science – 1 May 2003
Yang Liu/Magnetic Field
14
•
Applications for space-weather forecasts.
–
Coronal magnetic structure and solar wind.
› Based on coronal field extrapolation ( generally from a Potential Field Source
Surface model) and Wang & Sheeley’s empirical model.
–
Space weather based on an integrated model coupling efforts of modeling from the Sun
to the Earth.
› Provide boundary, initial condition for the integrated model (observation of synoptic
sun; solar coronal modeling from various models; etc.);
› Provide data representative to solar transient turbulence (such as change of
magnetic field described previously), solar eruptive mechanism, and etc… based on
SDO’s observation and basic research worldwide.
HMI Science – 1 May 2003
Yang Liu/Magnetic Field
15