1. The Solar Polar Field Reversal Observed By SOHO/MDI Yang Liu, J. Todd Hoeksema, X-P Zhao – Stanford University yliu@solar.stanford.edu

2. Outline Show reversal of polar field based on observational data; Show reversal of polar field based on observational data; Show evolution of large-scale magnetic field during solar cycle, especially in the period of polar field reversal; Show evolution of large-scale magnetic field during solar cycle, especially in the period of polar field reversal; Discuss change of the heliospheric magnetic field during polar field reversal. Discuss change of the heliospheric magnetic field during polar field reversal.

3. Magnetic field viewed from north pole

4. Magnetic field viewed from south pole

5. Polar field reversal (?)

6. Modeling polar field Polar field model: Solar minimum Solar maximum

7. Heliospheric field CR1960 (02/2000-03/2000) CR1975 (04/2001- 05/2001)

8. Coronal/Heliospheric fields

9. Coronal field during solar cycle

10. Interplanetary Magnetic Field (model & obs)

11. Summary Polar field reversal of cycle 23 occurred in 2001. The southern polar field reversed 10 month later than that of north polar field. Polar field reversal of cycle 23 occurred in 2001. The southern polar field reversed 10 month later than that of north polar field.