Meridional Circulation from ring-diagram analysis

Irene González Hernándezand the GONG++ team

National Solar ObservatoryTucson, Arizona

Meridional Circulation from ring-diagram analysis

Science motivation

Meridional circulation from ring

analysis. A quick history

Recent results

The future

Conclusions

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 from rings

Basu & Antia, 2003

Meridional Circulation from rings

Haber et al, 2002

Meridional Circulation from rings

González Hernández et al, 2006

Meridional Circulation from rings

González Hernández et al, 2006

Meridional Circulation from rings

Zaatri et al, 2006

Meridional Circulation from rings

Zaatri et al, 2006

Recent results from MDI

Courtesy of D. Haber

Recent results from GONG++

Recent results from GONG++

Meridional Circulation from small patches

Courtesy of B. Hindman and D. Haber

The future

GONG/MDI

Foreshortening / Projection

Differential rotation in the area studied

Effect of magnetic activity fitting

method

Other high latitude effects

HMI (Solar Dynamics Observatory)

VIM (Solar Orbiter)

Ring analysis has made a big contribution to the study of meridional circulation from the surface to approx. 30Mm.

New results confirm solar cycle dependence close to the surface from previous works but show almost no dependence at deeper layers

Multi-cell circulation needs to be confirmed

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

Several problems of the technique need to be addressed

Conclusions