Sub-surface evolution of AR 0486, AR 0069, and AR 9906 ... · M: square;X:diamond) and dense-pack regions (grid points; circle). Right: Number of X-ray flares and their intensity

Sub-surface evolution of AR 0486, AR 0069, and AR 9906, from GONG++ dataR. Komm, R. Howe, F. Hill, I. Gonzalez Hernandez, and C. Toner

National Solar Observatory, Tucson, AZ

Introduction y

We study the subsurface evolution of the flows near activeregions AR 0486, AR 0069, and AR 9906 during their diskpassage. We use a local helioseismology technique, ring-diagram analysis, to determine the flows in the upper 16Mm of the convection zone from high-resolution GONG data.Since the current analysis is limited to regions within 60o ofheliographic latitude and central meridian distance, we cannotmeasure flows near the solar limb associated with the activeregions that spawned the events on Apr 21 and Aug 24, 2002.We use kinetic helicity density as a measure of the complexityof the subsurface flows associated with these 3 active regions.

AR 0486 (Oct 25 – Nov 1, 2003)031029 X10 GONG data

GOES data

Left: Intensity, modulation, and magnetic field strength at thepeak of the flare event (top); same images after subtractinga reference frame (2nd); temporal variation at 3 locationsindicated by colored crosses (bottom). Right: Number of X-rayflares and their intensity as a function of dense-pack days. y

The scalar product of velocity and vorticity vector, the kinetichelicity density (Moffatt & Tsinober, 1992), shows significantvalues near the location of AR 0486 (–22.5o to –15o).

The temporal variation of the kinetic helicity density with depthfor 9 dense-pack regions and their signal-to-error ratios. Theregions that sample AR 0486 (–22.5o, –15o latitude; 285o

longitude) show large values with systematic variations.

References y

Haber D.A., Hindman, B.W., Toomre, J., Bogart, R.S., Larsen, R.M., &Hill, F. 2002, ApJ, 570, 885

Komm, R., Corbard, T., Durney, B.R., Gonzalez Hernandez, I., Hill, F.,Howe, R., & Toner, C. 2004, ApJ, 605, 554

Moffatt, H.K. & Tsinober, A. 1992, Annu. Rev. Fluid Mech., 24, 281Solar X-ray Flares from the GOES satellite (http://www.ngdc.noaa.gov)

Dense-Pack Ring-Diagram Analysis

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Each region is tracked using a surface rotation rate. A 2-dim cutof the power spectrum at a given temporal frequency shows aset of rings shifted by the horizontal flow field. These shifts areinverted to derive velocities with depth (Haber et al. 2002).

AR 0069 (Aug 13 – 21, 2002)

Left: Spatial distribution of X-ray flares by flare class (C: cross;M: square; X: diamond) and dense-pack regions (grid points;circle). Right: Number of X-ray flares and their intensity (GOESdata) as a function of dense-pack days (1664 min). y

The kinetic helicity density shows significant values near thelocation of AR 0069 (–15o to –7.5o). The sign changes withdepth distinguishing 3 ranges (similar to AR 0486 to the left).

Same as figure to the left. The regions that include AR 0069and the flare locations (–15o, –7.5o lat; 300o long and –7.5o lat ;307.5o long ) show large values and systematic variations. Thelarge flares occur near the end of the time period.

Acknowledgments

This work was supported by NASA grant NAG 5-11703. This work utilizes dataobtained by the Global Oscillation Network Group (GONG) program, managed bythe National Solar Observatory, which is operated by AURA, Inc. under a cooperativeagreement with the National Science Foundation. The data were acquired byinstruments operated by the Big Bear Solar Observatory, High Altitude Observatory,Learmonth Solar Observatory, Udaipur Solar Observatory, Instituto de Astrofısicade Canarias, and Cerro Tololo Interamerican Observatory. NSO/Kitt Peak data usedhere are produced cooperatively by NSF/NOAO, NASA/GSFC, and NOAA/SEL.

Summary y

The subsurface flows associated with AR 0486 and AR 0069show significant helicity values. A change in sign separates 3depth ranges.

The temporal variation of kinetic helicity is large and systematicfor AR 0486 and AR 0069 at dense-pack regions that includelocations of flare activity.

The subsurface flows associated with AR 9906 show smallhelicity values but a “dipolar” structure in the zonal vorticity.

The X10 flare on Oct 29, 2003 in AR 0486 was observed byGONG in intensity, modulation, and magnetic field strength.

AR 9906 (Apr 10 – 18, 2002)

Same as figure to the left for AR 9906. Compared with AR 0486and AR 0069, there is hardly any flare activity during the diskpassage of AR 9906. (AR 9906 is too close to the limb on Apr21, 2002 for a ring-diagram analysis.) y

The kinetic helicity density values associated with AR 9906 aremuch smaller compared to the values of the other two regionsand are hardly significant.

Same as figure to the left for AR 9906. Not much going onunder AR 9906 during its disk passage. However, AR 9906shows a “dipolar” structure in the zonal vorticity component, asignature of flare-producing regions.

The ring-fitting analysis is based on algorithms developed by Haber, Hindman, andLarsen with support from NASA and Stanford University. This poster was preparedwith Hardi Peter’s LaTex package.