1. Tsing Hua University, Taiwan Measurements of Acoustic Waves Scattered by Sunspots (Stanford, April 2011, LoHCo Workshop) Dean-Yi Chou Hui Zhao Ming-Hsu Yang Collaborators:

2. Waves Scattered by a Sunspot

3. Cameron et al. 2008 The incident wave is a plane wave packet. Cross-correlation between the reference line and each point

4. Data HMI: 30 July – 5 August 2010 (13,583 frames) NOAA 11092

6. The cross-correlation function relates to the wave function, but is not the wave function!!!

8. Comparison of CCF and Wave Initially, the wave is narrower than the CCF. Initially, the wave is narrower than the CCF. As it propagates, the width of wave increases faster than the width of CCF As it propagates, the width of wave increases faster than the width of CCF because of dispersion. because of dispersion.

10. Interference Patterns from total waves from total waves

11. A Phenomenological Model wave equation in QS σ describes magnetic regions σ describes magnetic regions wave equation with magnetic fields solution If Green’s function

12. Scattered Waves from a Model constant σ inside the circular area constant σ inside the circular area

13. The End