Transcript Ken_Schatten06

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