February 26, 2007 KIPAC Workshop on Magnetism Modeling/Inferring Coronal And Heliospheric Field From...

February 26, 2007 KIPAC Workshop on Magnetism

Modeling/Inferring Coronal And Modeling/Inferring Coronal And Heliospheric Field From Heliospheric Field From

Photospheric Magnetic FieldPhotospheric Magnetic Field

Yang Liu – Stanford Yang Liu – Stanford UniversityUniversity

[email protected]@solar.stanford.edu


OutlineOutline

HMI/SDO observables;HMI/SDO observables; HMI science with vector HMI science with vector

magnetograms;magnetograms; Modeling the coronal and Modeling the coronal and

heliospheric field from the heliospheric field from the photospheric magnetic field.photospheric magnetic field.


HMI observablesHMI observables Continuum intensity;Continuum intensity;

Full disk with a CCD of 4096×4096 Full disk with a CCD of 4096×4096 pixels;pixels;

resolution is 0.5’’/pixel;resolution is 0.5’’/pixel; Cadence less than 1 minute.Cadence less than 1 minute.

Doppler velocity;Doppler velocity; Full disk with a CCD of 4096×4096 Full disk with a CCD of 4096×4096

pixels;pixels; resolution is 0.5’’/pixel;resolution is 0.5’’/pixel; Cadence less than 1 minute.Cadence less than 1 minute.

Line-of-sight magnetic field;Line-of-sight magnetic field; Full disk with a CCD of 4096×4096 Full disk with a CCD of 4096×4096

pixels;pixels; resolution is 0.5’’/pixel;resolution is 0.5’’/pixel; Cadence less than 1 minute.Cadence less than 1 minute.

Vector magnetic field.Vector magnetic field. Full disk with a CCD of 4096×4096 Full disk with a CCD of 4096×4096

pixels;pixels; resolution is 0.5’’/pixel;resolution is 0.5’’/pixel; Cadence less than 2 minute.Cadence less than 2 minute.More informa

tion


HMI Science (Magnetic HMI Science (Magnetic Field)Field)

Sources and drivers of solar activity Sources and drivers of solar activity and disturbances;and disturbances; Evolution of small-scale magnetic elements (coronal Evolution of small-scale magnetic elements (coronal

heating);heating); Emergence of magnetic flux and solar transient events;Emergence of magnetic flux and solar transient events; Magnetic configuration and mechanisms of solar flares Magnetic configuration and mechanisms of solar flares

and CMEs.and CMEs. Links between the internal processes Links between the internal processes

and dynamics of the corona and and dynamics of the corona and heliosphere;heliosphere; Complexity and energetics of solar corona;Complexity and energetics of solar corona; Coronal magnetic structure and solar wind.Coronal magnetic structure and solar wind.

Precursors of solar disturbances for Precursors of solar disturbances for space-weather forecast.space-weather forecast. Determination of magnetic cloud Bs events.Determination of magnetic cloud Bs events.


Modeling the coronal and Modeling the coronal and heliospheric field.heliospheric field.

Potential field source surface model Potential field source surface model (PFSS);(PFSS);

Hybrid model;Hybrid model; Non-linear force-free field model;Non-linear force-free field model; MHD simulation.MHD simulation.

February 26, 2007 KIPAC Workshop on MagnetismSchatten, Cosmic Electrodynamics, 2, 232, 1971.

),(YrB + rA = ),(r, lm1)+-(l

lml

lm

l

-l=m0 = l

where,

0 = 2

Potential Field Source Potential Field Source Surface ModelSurface Model

Coefficients Alm and Blm are determined

from the boundary conditions.

j = 0

From Arge 2005.


Solar Boundary: Magnetic Solar Boundary: Magnetic FieldField


Potential field source Potential field source surface modelsurface model

PFSS


Validation of PFSSValidation of PFSS

Zhao and Webb (2003)


3D MHD simulation shows that type 2 and 3 3D MHD simulation shows that type 2 and 3 CMEs are faster than type 1.CMEs are faster than type 1.


Data Data We looked for the halo CMEs from the CMEs list We looked for the halo CMEs from the CMEs list

of Gopalswamy’s group. 91 halo CMEs in the of Gopalswamy’s group. 91 halo CMEs in the period from 2000 to 2004 were chosen. The solar period from 2000 to 2004 were chosen. The solar sources were identified by that group, and were sources were identified by that group, and were confirmed by other groups/works.confirmed by other groups/works.

Type 1Type 1 Type 2Type 2 Type 3Type 3

numbernumber 3939 4646 1414

PercentagePercentage 39%39% 47%47% 14%14%

Median speed (km/s)Median speed (km/s) 728728 12081208 14431443

Mean speed (km/s)Mean speed (km/s) 883±403883±403 1345±5961345±596 1530±7361530±736


Speed distribution for type 1 and types 2&3 CMEs. The types 2 & 3 CMEs are significantly faster than type 1 CMEs.


Distributions of flare class for type 1 and 2 & 3 CMEs. They have very similar distributions. This suggests that the difference of the CMEs speed is not biased by flare importance.

Wang & Sheeley (1990) simulate the solar wind speed at Earth for ~20 year period (1967-1988).

i) Test hypothesis that Vsw and fs = (R/Rss)2[BP(R)/BP(Rss)] are inversely

correlated.

ii) Correlation between observed and simulated wind speed found.

Simulated speedObserved Speed

Wang & Sheeley, ApJ, 355, 726, 1990.

Long-Term Comparison of Observations and Solar Long-Term Comparison of Observations and Solar Wind Speed Predictions Using the PFSSWind Speed Predictions Using the PFSS

From Arge (2005)

NSO750

650

550

450

350

250

750

MWOCR1988 CR1987 CR1986

650

550

450

350

250

de Toma and Arge (2004)



Measurements

Model Calculation

Wang et al. 2000

Global Coronal Field: Extrapolations and ObservationsGlobal Coronal Field: Extrapolations and Observations

Comparison of photospheric field extrapolations (left) to white light (pB) image (right) indicate a degree of qualitative correlation between closed field lines and streamers

White light (pB) data HAO/MLSO/Mk3Photospheric field extrapolation (MWO)

Gibson and Arge


Hybrid modelsHybrid models

Potential field-current sheet model (PFCS Potential field-current sheet model (PFCS model, Schatten 1971);model, Schatten 1971);

Horizontal current-source surface model ( Horizontal current-source surface model ( HCSS model, Zhao & Hoeksema, 1992);HCSS model, Zhao & Hoeksema, 1992);

Horizontal current-current sheet model Horizontal current-current sheet model (HCCS model, Zhao & Hoeksema, 1994);(HCCS model, Zhao & Hoeksema, 1994);

Current sheet-source surface model Current sheet-source surface model (CSSS model, Zhao & Hoeksema, 1995).(CSSS model, Zhao & Hoeksema, 1995).


Current-sheet source Current-sheet source surface modelsurface model

From Zhao & Hoeksema 1995.


Validation of CSSS modelValidation of CSSS model

From Zhao, 1999.


Non-linear force-free Non-linear force-free field modelfield modelWiegelmann, Solar

Physics, in press, 2007.

Case 1: use boundary data on both photosphere and source surface in 30<theta<150;

Case 2: use boundary data on both photosphere and source surface in delta_theta<theta<180-delta_theta

Case 3: use boundary data on both photosphere and source surface.

Case 4: only use boundary data on photosphere. Magnetic field on the source surface is replaced by the initial potential field.


MHD simulationMHD simulation

Magnetic Field Lines(MHD Model)

Polarization Brightness(MHD Model)

Eclipse (Williams College)*& SOHO LASCO C2 Images

Solar eclipse on March 29, 2006. Simulation was done by Linker et al at Science Application International Corporation (SAIC) at San Diego.


HMI simulationHMI simulation Extra boundary data help improve simulation Extra boundary data help improve simulation

results.results.

Hayashi et al 2006


Comparison of MHD and Comparison of MHD and PFSSPFSS

From Riley et al, 2006, ApJ.

PFSS

MHD

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