Update to the Babcock-Leighton Solar Dynamo and Activity Predictions

Kenneth SchattenAi-solutions

Outline• UPDATE BABCOCK-LEIGHTON DYNAMO

1) Shallow Dynamo

2) Percolation controls small-scale motion

3) Magnetic forces control large-scale motion

• PERCOLATION COMES IN TWO FLAVORS:1) Highly Superadiabatic: Convection drives like-sign Ephemeral Regions (EPRs ) into sunspots

2) Normal: Normal T structure: field concentrations disperse: spots-> faculae / plage

• MODELING:

Cellular Automata Modeling – relate to observations & solar dynamo

• PREDICTION:

Solar Cycle #24 Rz~75; F10 ~125 in ~2012-3

Babcock-Leighton Solar Dynamo

Magnetic Carpet & Percolation

From Lockheed Group

Above the PhotosphereBelow the Photosphere:In regions of high superadiabaticity, like fields drawn together

Percolation Allows Field to Separate from the Flow – Remain Shallow

Falling Leaf Instability

Superadiabatic Temperature Gradient: Large in Top Layers

Overview – Shallow Dynamo:A) and B) – Superadiabatic Percolation

C) Normal Percolation

Overview – Shallow DynamoLike Babcock-Leighton, but with 1) EPRs and 2) motio n from B forces

Superadiabatic Percolation Model

Percolation

Time Series of Superadiabatic

Percolation of Ephemeral Regions

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2

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Super + Drift Normal + DriftSuperadiabatic

Modeling and Observations

Modeling and Observations

400 & 100 Year ModelingPolar Fields vs. Time

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Different Longitudes, Both Polar Fields

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Series5 Series6 Series7 Series8

How Spot Flux Imbalances Form(Why spots are not all equal bipoles)

SODA index vs time, years

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1975 1980 1985 1990 1995 2000 2005 2010

Time, years

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Toroidal proxy (radio flux) Polar Field (soda units) SODA index

SODA (Solar Dynamo Amplitude) Index

Schatten Prediction: Weak Solar Cycle 24Use of the idea that the Sun’s polar field is a precursor for the

next cycle’s activity level [Schatten et al. (1978)]; Svalgaard et al. (GRL, 32, L01104, 2005); Schatten (GRL,32,L21106, 2005)

F10.7 Observations and Predicts

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Observations Predicted in Advance

Geomagnetic Activity - Sunspot Correlation

Activity Index (aa)

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imum

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spot

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Rz)

Conclusions• UPDATE BABCOCK-LEIGHTON DYNAMO:

We update with 3 ideas: 1) Shallow Dynamo, 2) Percolation in two flavors, a nd 3) Magnetic forces help drive faculae/plage towards poles

• PERCOLATION IN TWO FLAVORS: 1) Highly Superadiabatic: Convection drives like-sign Ephemeral Regions (EPRs ) into sunspots2) Normal: Normal T structure: field concentrations disperse: spots-> faculae

• MAGNETIC FORCES: Rather than fields moving towards poles via diffusion/meridional transport, we suggest magnetic forces, mB, on subsurface field elements play a prominent role– yie ld dynamo

• MODELING: Cellular Automata Modeling seems to fit s olar dynamo

• PREDICTION: Solar Cycle #24 Rz~75; F10 ~125 in ~201 2-3

Backup

LONG-TERM SOLAR OBSERVATIONSInternational/Zurich Sunspot Number vs. Year

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51 64 1032 71 8 91 11 12 13 14 15 16 1718 19 2021 235 22

SODA index vs time, years

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1975 1980 1985 1990 1995 2000 2005 2010

Time, years

SO

DA

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Toroidal proxy (radio flux) Polar Field (soda units) SODA index

Babcock’s shallow dynamo view

Babcock 1961, ApJ, 133, 572

Why Field Separates From Flow: Leaf Instability, and Stays Near Photosphere