Subsurface Flows from ring-diagram analysis

Irene González Hernández

National Solar ObservatoryTucson, Arizona

Subsurface flows from ring-diagram analysis

Ring-diagrams technique

Differential rotation

Meridional circulation

Dynamics of active regions and

filaments

Results at different heights

Future work and conclusions

Ring-diagrams technique

Hill, F; 1988, ApJ,333,996

Patrón, J.; Hill, F.;Rhodes, E.J.,Jr.;Korzennik,S. G. and Cacciani,A., 1995, ApJ, 455,746

16o16

64 m

in

González Hernández, I.; 1998 PhD tesis, University of La Laguna

González Hernández, I.; Patrón,J.; Roca Cortés, T.; Bogart, R.S.; Hill, F.; Rhodes,E.J.,Jr.,2000, ApJ

Flows from rings: synoptic maps

Courtesy of R. Komm

Differential Rotation

Radial variation of the mean rotation rate, shifted to give a zero rate at the surface, for global inversions (curves mark error bounds) of MDI data and local inversions of MDI (filled circles) and GONG (open diamonds) data at latitudes 0(top left), 15(top right), 30 (bottom left) and 45 (bottom right).

Howe, R. et al., 2006, Solar Physics ,235,1.

Zonal torsional oscillation

Howe, R. et al., 2006, Solar Physics, 235,1.

Zonal flow residuals from global helioseismology and local helioseismology (ring-diagrams) at 0.99Rsun

North-South asymmetry

The latitudinal variation is most likely a consequence of the solar-cycle variation of the zonal flow, the torsional oscillation pattern.

The zonal flow is predominantly faster in the southern hemisphere that in the northern one. This differences increase with latitude about 25-degrees, and with depth.

Zaatri, A. et al, 2006, Solar Physics, 236,227

Temporal variation of the zonal flow in the Northern (dark grey) and Southern (light grey) hemisphere at four latitudes and four depths. The surface rotation rate has been subtracted (Snodgrass, 1984). The line thickness represents about two standard deviations of the formal undertainty. The top row shows, for comparison, the time scale in Carrington Rotations.

Meridional Circulation and Dynamo Models

Dikpati, Mausumi; Gilman, Peter A. "Flux-Transport Dynamos with α-Effect from Global Instability of Tachocline Differential Rotation: A Solution for Magnetic Parity Selection in the Sun". 2001, ApJ, 559, 428

Gilman, P.A and Miesch, M. "Limits to Penetration of Meridional Circulation Below the Solar Convection Zone“, 2004, ApJ, 611, 568.

Giles, P., 2000, PhD Thesis, Stanford University. Haber, Deborah A.; Hindman, Bradley W.; Toomre, Juri; Bogart, Richard S.; Larsen,

Rasmus M.; Hill, Frank. "Evolving Submerged Meridional Circulation Cells within the Upper Convection Zone Revealed by Ring-Diagram Analysis". 2002,  ApJ,570, 855

McDonald, E.; Dikpati, M. "Evolution of Large-scale Solar Magnetic Fields in the Presence of a Multi-cell Meridional Flow". 2004,American Astronomical Society Meeting 204, #53.06

Courtesy of E. McDonald

A quick history of Meridional Circulation from rings

González Hernández, I, Patrόn, J, Bogart, R. S. and the SOI Ring Diagram Team, 1999, ApJ 510, L153

Basu, S. and Antia, H.M, 2002 Proceedings of the SOHO 11 Symposium 2003, ApJ 585, 553

Haber, D.A., Hindman, B. W.,Toomre, J., Bogart, R.S., Larsen, R.M., Hill, F.,2002, ApJ 570, 855.

González Hernández, I., Komm, R.,Hill,F.,Howe,R., Corbard, T. and Haber, D.A., 2006, ApJ 638, 576

Zaatri, A., Komm,R., Gonzalez Hernandez, I., Howe, R. and Corbard, T., 2006, SoPh 236, 227

Meridional Circulation

Basu & Antia, 2003

Meridional Circulation

Haber et al, 2002

Meridional Circulation

González Hernández et al, 2006

Meridional Circulation

González Hernández et al, 2006

Meridional Circulation

Zaatri et al, 2006

Meridional Circulation

Zaatri et al, 2006

Recent results from MDI

Haber, D. et al., 2006

Recent results from GONG++

Recent results from GONG++

Meridional Circulation from small patches

Courtesy of B. Hindman and D. Haber

Subsurface flows and their relation to surface magnetic activity

NOAA10069: 300o Longitude, −7.5o Latitude Courtesy of R. Komm

Flows in filaments

Daily high-resolution flow maps obtained using 4 ｡ -diameter tiles. The maps span four consecutive days: (a) 2002 March 30, (b) 2002 March 31, (c) 2002 April 1, and (d) 2002 April 2.

Regions of opposite magnetic polarity, as determined from MDI magnetograms, are indicated in green and red. The dark contour line

shows the position of a filament as observed in BBSO H images. On March 31when BBSO images were unavailable, the contour from the previous

day is indicated with a dashed line. Four long-lived convection cells span the location of the

filament and are marked with numerals I ﾐ IV (in

white). The filament runs through the center of

these cells and the apparent flow along the

neutral line is complicated. The widening of the

filament over the span of the four days is probably due to projection of the filament

against the solar disk as the region rotates

across the Sun's visible surface.

Hindman, B., Haber, D. and Toomre, J. ApJ, 2006, 653, 725

Flows in filaments

Daily high-resolution flow maps obtained using 2 ｡ -diameter tiles, zoomed in to cover the region outlined with the white dashed box in previous fig. The maps span the same four days displayed in the previous fig: (a) 2002 March 30, (b) 2002 March 31, (c) 2002 April 1, and (d) 2002 April 2. The finer resolution available in these maps

indicate that there is a complex interaction between the flow cells and photospheric magnetism.

Hindman, B., Haber, D. and Toomre, J. ApJ, 2006, 653, 725

Flows at different heights

Subsurface flow maps for Jan 18, 2003(left) and Jan 19, 2003 (right). Blue arrows show flows obtained from the Ni line and red from the K line.

Differences

Jain, K. et al, 2006

Flows from untracked regions

Courtesy of R Bogart, C Rabello-Soares and S. Basu

Flows from untracked regions

Courtesy of R Bogart, C Rabello-Soares and S. Basu

The future

GONG/MDI

3-Dimensional inversions

Large scale flows:

Foreshortening / Projection

Other high latitude effects

Flows in active areas

Effect of magnetic activity fitting method

More analysis

HMI (Solar Dynamics Observatory)

VIM (Solar Orbiter)

Ring analysis has made a significant contribution to the study of large scale flows from the surface to approx. 30Mm.

New results confirm the solar cycle dependence of meridional circulation close to the surface found by previous works, but show almost no dependence at deeper layers. Surface activity effect is being investigated.

Multi-cell circulation needs to be confirmed

HRRA: Flows in active regions and filaments

Several problems of the technique need to be addressed

We are limited in latitude to +/- 50 degrees Higher resolution observations (HMI) Observations off the ecliptic (Solar Orbiter mission)

The stellar connection: “Try to use dynamo models that do “well” in the solar case” (M.

Rempel)

Conclusions