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Variations of Solar Acoustic Radius from GONG low-L data

Variations of Solar Acoustic Radius from GONG low-L data. Shukur Kholikov NSO/GONG. Outline. Auto-correlation analysis Data: GONG, BISON, VIRGO/SPM Large separation or acoustic radius measurements Results Meridional flows from SH zonal modes Conclusions and future work. ACF.

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Variations of Solar Acoustic Radius from GONG low-L data

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  1. Variations of Solar Acoustic Radius from GONG low-L data Shukur Kholikov NSO/GONG

  2. Outline • Auto-correlation analysis • Data: GONG, BISON, VIRGO/SPM • Large separation or acoustic radius measurements • Results • Meridional flows from SH zonal modes • Conclusions and future work

  3. ACF

  4. Large separations from GONG frequencies

  5. Large separations from BISON frequencies

  6. Large separations from ACF L= 0, 2

  7. Travel times: GONG

  8. Correlation with the activity

  9. Relative changes of acoustic radius: MDI, GONG

  10. Relative changes of acoustic radius: BISON

  11. Relative changes of acoustic radius: VIRGO/SPM

  12. Conclusions • Precise measurements of large separation • Possibly we may estimate change of upper reflection boundary during the activity cycle • Applicable to astroseismology, stellar activity

  13. Meridional travel time differences using GONG (m=0) SH time series L=0-200

  14. Average CCF T=1 gong month ∆=17º =3 mHz

  15. Comparison travel time differences Directly from velocity images From M=0 SH coefficients From reconstructed images using all-L SH coefficients

  16. Average travel time differences

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