Babcock-Leighton DynamoTheory and Solar Cycle #24

Kenneth SchattenAi-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 forfuture active region fields.

• Near Solar Minimum, the Polar field of theSun extends past the Earth. This affectsgeomagnetic activity: hence geomagprecursors may serve to predict the Sun’sactivity.

General Dynamo Theory –DISKDYNAMO (MHD – FIELDS

AMPLIFY PRE-EXISTING FIELD)

Babcock-Leighton model Babcock-Leighton model

Traditional Solar Physics• Hale’s Laws• Spoerer Butterfly

Diagram• Joy’s Law

How the Sun ‘Broadcasts’ theState of its Internal Mag. Field

2 STEPS:

STEP 1: Polar field atsolar minimum actsas a precursor for thetoroidal field (activeregions).

How the Sun ‘Broadcasts’ theState of its Internal Mag. Field

Schatten, K.H., “Current Sheet MagneticModel for the Solar Corona," CosmicElectrodynamics, 11, 4, AsilomarConference on the Solar Wind, (1971).

STEP 2:Near solar min., the solar wind extends thepolar field into the interplanetary field. Whenit dips low enough to reach the ecliptic itcan affect geomag. activity. This allows it toserve as a precursor for next cycle’sactivity.

Shown are the computed field lines ontop of structure of the eclipse of Nov.12, 1966.

The Sun’s Polar Field

We often use a “SODA (Solar Dynamo Amplitude) Index, whichincorporates the Sun’s Toroidal and Poloidal Fields, but to reducecomplexity are showing the polar fields alone, as these have less“active region noise.”

Sun’s Polar Field, 10**-2 G

Mt Wilson Solar Observatory (MWO)

Wilcox Solar Obs. (WSO)

F10.7 Observations andPredictionsF10.7 Observations and Predicts

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Schatten et al. Predicted in advance

Observations

Solar Forecast for Cycle #24

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Where did the Sun’s Field go?‘Normal’ Polar

Coronal Holes atSolar Minimum

April, May, 2005 STAR SOHO/MDIApril, May, 2005 STAR SOHO/MDICoronal Hole MapCoronal Hole Map

October, 1996 Coronal Hole Drawing,October, 1996 Coronal Hole Drawing,Karen Harvey, using Karen Harvey, using KittKitt Peak He 10830 line Peak He 10830 line

Yohkoh Soft X-ray Image Aug.1996

2005

Idealized Model of“Typical” Solar MinimumCorona

Present Coronal Holes

?s FOR MODELS PREDICTINGLARGE CYCLE #24

• DIKPATI + MODEL: FEEL + TOWARDS PHYS.MODELS, BUT SOME ?s ARISE:1) DATAANALYSIS ? ,2) WHY SHOULD FLOW FOLLOWTHEIR PARTICULAR PATTERN?

• WHAT EXPLAINS THE OBSERVED DOWNTURNIN THE SUN’S POLAR FIELD FOR THE LASTSEVERAL YEARS?

• THE POLAR FIELD & ITS PROXIES (e.g. POLARFACULAE) CORRELATE WELL WITH THE NEXTCYCLE’S ACTIVITY. WHAT EXPLAINS THIS (IFNOT THE B-L MODEL)?

SUMMARY/CONCLUSIONS

• BABCOCK-LEIGHTON DYNAMO THEORY• POLAR FIELD (OR PROXY) IS

PRECURSOR FOR NEXT CYCLE’SACTIVITY

• CURRENTLY POLAR FIELD IS LOW• THEREFORE, IF B-L THEORY & OUR

INTERPRETATION OF IT IS RIGHT, CYCLE #24 WILL BE LOW