Exploring Systematic Effects in Ring Diagram Analysis Techniques

Transcription

1 Exploring Systematic Effects in Ring Diagram Analysis Techniques (1) (2) (2) Richard S. Bogart, Charles S. Baldner, Sarbani Basu, Deborah A. Haber (3), Maria Cristina Rabello-Soares(1) (1) HEPL, Stanford University (2) Astronomy Department, Yale University (3) JILA, University of Colorado region extent = 15. deg; Postels projection grid spacing 15. deg New Advances in Helio- and Astero-Seismology, Rio de Janeiro, 1 11 Aug 9

2 rotational rate differential (longitude) 1. Tracking: (1) isolates the region in the feature of interest (2) symmetrizes the spectra of the observable tangential rotational velocity differential at 1. R from Carrington delta-omega [deg/day] Supergranules (Snodgrass & Ulrich) -3. Sunspots (Newton & Nunn) Photosphere (Snodgrass) rotational rate differential (arc) Supergranules (Snodgrass & Ulrich) Sunspots (Newton & Nunn) 5.. delta-u [m/s] Photosphere (Snodgrass) delta-omega [deg/day] Supergranules (Snodgrass & Ulrich) Sunspots (Newton & Nunn) Photosphere (Snodgrass) New Advances in Helio- and Astero-Seismology, Rio de Janeiro, 1 11 Aug 9-4.

3 delta-u [m/s] tangential rotational velocity differential at 1. R tangential rotational velocity differential at 1. R from Carrington +.1 urad/s Carrington +.1 µrad/s Carrington -.1 µrad/s 1. Supergranules (Snodgrass & Ulrich) 5. Sunspots (Newton & Nunn). Photosphere (Snodgrass) delta-u [m/s] tangential rotational velocity differential at 1. R from Carrington -.1 urad/s Supergranules (Snodgrass & Ulrich) Sunspots (Newton & Nunn) Photosphere (Snodgrass) tangential 3. rotational 45.velocity 6. differential 75.at 1.9. R from Carrington Carrington Carrington -.3 µrad/s 1. Supergranules (Snodgrass & Ulrich) Sunspots (Newton & Nunn) delta-u [m/s] Photosphere (Snodgrass) delta-u [m/s] New Advances in Helio- and Astero-Seismology, Rio de Janeiro, 1 11 Aug 9

4 tangential rotational velocity differential at 1. R Carrington -.6 µrad/sec Carrington -.9 µrad/sec delta-u [m/s] 3.. delta-u [m/s] New Advances in Helio- and Astero-Seismology, Rio de Janeiro, 1 11 Aug 9

5 dense-pack of tracked cubes for one full rotation at six different rigid rotation rates: diameter regions on 7.5 centers extending 52.5 deg from equator/central meridian each region tracked 1664 min from MDI full-disc Dopplergrams (~15 rotation) dense-packs tracked every 15 in Carrington rotation 24 sets analyzed with OLA inversions to depths of ~1 Mm CR 1988: 3 III 26 IV 2 (B ~ -5 ) New Advances in Helio- and Astero-Seismology, Rio de Janeiro, 1 11 Aug 9

6 Mean Ux (24 central meridian sets) vs track rate, by latitude vs latitude, by track rate New Advances in Helio- and Astero-Seismology, Rio de Janeiro, 1 11 Aug 9

7 Mean Uy (24 central meridian sets) vs track rate, by latitude vs latitude, by track rate New Advances in Helio- and Astero-Seismology, Rio de Janeiro, 1 11 Aug 9

8 Mean wavenumber differences (24 central meridian sets) vs track rate, by latitude vs latitude, by track rate New Advances in Helio- and Astero-Seismology, Rio de Janeiro, 1 11 Aug 9

9 Variation of Ux with latitude at selected depths by tracking rate (24 central meridian sets) New Advances in Helio- and Astero-Seismology, Rio de Janeiro, 1 11 Aug 9

10 Variation of U with depth at selected latitudes by tracking rate (24 central meridian sets) Ux Uy New Advances in Helio- and Astero-Seismology, Rio de Janeiro, 1 11 Aug 9

11 Variation of Uy with latitude at selected depths by tracking rate (24 central meridian sets) New Advances in Helio- and Astero-Seismology, Rio de Janeiro, 1 11 Aug 9

12 Time variation of Ux near surface at latitude 15 by tracking rate New Advances in Helio- and Astero-Seismology, Rio de Janeiro, 1 11 Aug 9

13 Synoptic maps of Ux (central meridian only) at selected depths for various tracking rates New Advances in Helio- and Astero-Seismology, Rio de Janeiro, 1 11 Aug 9

14 Synoptic maps of Uy (central meridian only) at selected depths for various tracking rates New Advances in Helio- and Astero-Seismology, Rio de Janeiro, 1 11 Aug 9

15 Synoptic maps of horizontal flow vectors at depths 1, 7, & 1 Mm, with tracking at different rigid rates 6 24 Apr 2 CR 1988 CR+.1 Depth = 1. Mm 7 day avg CR Mar 2 C 6 24 Apr 2 CR 1988 CR-.9 Depth = 1. Mm 7 day avg CR Mar 2 C Apr 2 CR 1988 Depth = 7. Mm CR Mar 2 B Apr 2 CR 1988 Depth = 7. Mm CR Mar 2 B Apr 2 CR 1988 Depth = 1. Mm CR Mar 2 A Apr 2 CR 1988 Depth = 1. Mm CR Mar 2 A m/s Carrington Longitude m/s Carrington Longitude New Advances in Helio- and Astero-Seismology, Rio de Janeiro, 1 11 Aug 9

16 Synoptic maps of horizontal residual vectors at depths 1, 7, & 1 Mm, with tracking at different rigid rates 6 24 Apr 2 CR 1988 CR+.1 Depth = 1. Mm 7 day avg CR Mar 2 C 6 24 Apr 2 CR 1988 CR-.9 Depth = 1. Mm 7 day avg CR Mar 2 C Apr 2 CR 1988 Depth = 7. Mm CR Mar 2 B Apr 2 CR 1988 Depth = 1. Mm CR Mar 2 A Apr 2 CR 1988 Depth = 7. Mm CR Mar 2 B Apr 2 CR 1988 Depth = 1. Mm CR Mar 2 A m/s Carrington Longitude m/s Carrington Longitude New Advances in Helio- and Astero-Seismology, Rio de Janeiro, 1 11 Aug 9

17 Synoptic maps of horizontal residual vectors at depths 1, 7, & 1 Mm, with tracking at differential and slow rigid rates 6 24 Apr 2 CR 1988 Snodgrass Depth = 1. Mm 7 day avg CR Mar 2 C 6 24 Apr 2 CR 1988 CR-.9 Depth = 1. Mm 7 day avg CR Mar 2 C Apr 2 CR 1988 Depth = 7. Mm CR Mar 2 B Apr 2 CR 1988 Depth = 1. Mm CR Mar 2 A Apr 2 CR 1988 Depth = 7. Mm CR Mar 2 B Apr 2 CR 1988 Depth = 1. Mm CR Mar 2 A m/s Carrington Longitude m/s Carrington Longitude New Advances in Helio- and Astero-Seismology, Rio de Janeiro, 1 11 Aug 9

18 Conclusions Ux parameter is recovered reliably when allowance is made for tracking rate, up to differentials of over 6 m/s; the small hemispheric asymmetry at high latitudes is independent of tracking rate Uy parameter may be subject to small systematic effects with tracking rate at high latitudes where foreshortening is large, possibly affecting inversion results for mean meridional flows at depth absolute frequency determinations vary systematically with the tracking rate differential, though the variations are within the error estimates horizontal flow structures are recovered reliably at all depths when allowance is made for tracking rate New Advances in Helio- and Astero-Seismology, Rio de Janeiro, 1 11 Aug 9