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Babcock-Leighton Dynamo Theory and Solar Cycle #24 Kenneth Schatten Ai-solutions OUTLINE • SA PRED: FEEL+ TO PHYS. MODELS: DIKPATI +. • PRECURSORS PREDS.: GEOMAGNETIC & SOLAR • BABCOCK – LEIGHTON DYNAMO • THE SUN’S POLAR FIELD • PREDICTION FOR CYCLE #24 • ?s FOR MODELS PREDICTING LARGE CYCLE#24 • SUMMARY AND CONCLUSIONS SOLAR ACTIVITY Geomagnetic Precursors, Kane Solar Precursors : Brief Theory • General dynamo theory – DISK DYNAMO • Solar Babcock-Leighton model • Solar Dynamo Method - Magnetic fields at the Sun’s Poles are the precursors for future active region fields. • Near Solar Minimum, the Polar field of the Sun extends past the Earth. This affects geomagnetic activity: hence geomag precursors may serve to predict the Sun’s activity. General Dynamo Theory –DISK DYNAMO (MHD – FIELDS AMPLIFY PRE-EXISTING FIELD) Babcock-Leighton model Traditional Solar Physics • Hale’s Laws • Spoerer Butterfly Diagram • Joy’s Law How the Sun ‘Broadcasts’ the State of its Internal Mag. Field 2 STEPS: STEP 1: Polar field at solar minimum acts as a precursor for the toroidal field (active regions). How the Sun ‘Broadcasts’ the State of its Internal Mag. Field STEP 2: Near solar min., the solar wind extends the polar field into the interplanetary field. When it dips low enough to reach the ecliptic it can affect geomag. activity. This allows it to serve as a precursor for next cycle’s activity. Shown are the computed field lines on top of structure of the eclipse of Nov. 12, 1966. Schatten, K.H., “Current Sheet Magnetic Model for the Solar Corona," Cosmic Electrodynamics, 11, 4, Asilomar Conference on the Solar Wind, (1971). The Sun’s Polar Field Sun’s Polar Field, 10* * -2 G Wilc o x So la r O b s. (WSO ) M t W ilso n So la r O b se rva to ry (M WO ) We often use a “SODA (Solar Dynamo Amplitude) Index, which incorporates the Sun’s Toroidal and Poloidal Fields, but to reduce complexity are showing the polar fields alone, as these have less “active region noise.” F10.7 Observations and Predictions F10.7 Observations and Predicts Observations Predicted in Advance 350 300 Radio Flux, F10.7 250 Observations 200 150 100 #22 # 21 50 # 23 # 24 Sc ha tte n e t a l. Pre d ic te d in a d va nc e 0 1940 1950 1960 1970 1980 1990 Year 2000 2010 2020 2030 Solar Forecast for Cycle #24 Mean F10.7 Predicted +2 Sigma Uncertainty -2 Sigma Uncertainty 160 140 Radio Flux, F10.7 cm 120 100 80 60 40 20 0 2004 2006 2008 2010 2012 Time, Years 2014 2016 2018 2020 Where did the Sun’s Field go? ‘Normal’ Polar Coronal Holes at Solar Minimum Present Coronal Holes Idealized Model of “Typical” Solar Minimum Corona Yohkoh Soft XOctober, 1996 Coronal Hole Drawing, ray Image Aug. Karen Harvey, using Kitt Peak He 10830 line 1996 2005 April, May, 2005 STAR SOHO/MDI Coronal Hole Map ?s FOR MODELS PREDICTING LARGE CYCLE #24 • DIKPATI + MODEL: FEEL + TOWARDS PHYS. MODELS, BUT SOME ?s ARISE:1) DATA ANALYSIS ? ,2) WHY SHOULD FLOW FOLLOW THEIR PARTICULAR PATTERN? • WHAT EXPLAINS THE OBSERVED DOWNTURN IN THE SUN’S POLAR FIELD FOR THE LAST SEVERAL YEARS? • THE POLAR FIELD & ITS PROXIES (e.g. POLAR FACULAE) CORRELATE WELL WITH THE NEXT CYCLE’S ACTIVITY. WHAT EXPLAINS THIS (IF NOT THE B-L MODEL)? SUMMARY/CONCLUSIONS • BABCOCK-LEIGHTON DYNAMO THEORY • POLAR FIELD (OR PROXY) IS PRECURSOR FOR NEXT CYCLE’S ACTIVITY • CURRENTLY POLAR FIELD IS LOW • THEREFORE, IF B-L THEORY & OUR INTERPRETATION OF IT IS RIGHT, CYCLE #24 WILL BE LOW