Solar QuasiBiennial Fluctuations

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Solar Quasi-BiennialFluctuations

• Csilla Szasz and Johan Kero

Heliophysical Observatory Debrecen
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Swedish Institute of Space Physics
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The Butterfly Diagram of the Present Debrecen
Photoheliographic Data (DPD)
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Umbra-Penumbra Area Ratio for Sunspots in the DPD
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U/P Area Ratio for Sunspot Groups in the Debrecen
Photoheliographic Results (DPR)
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Mean U/P Area Ratio for Different Sizes of Spots
in the DPD

• U P Area lt 15
• 15 U P Area lt 50
• 50 U P Area lt 300

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U/P Area Ratio as a Function of the Umbra Area

• 1993 Max
• 1995 Max
• 1988 Min
• 1994 Min

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PSD Estimate for Monthly Mean U/P Area Ratio
(with Subtracted DC-component)
1986 - 1989
1993 - 1996
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Best Sinusoidal Fit - T 24.2 months
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Best Polynomial Fit
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Possible Physical Interpretations (still under
investigation)

• A fluctuation in the temperature and plasma
  pressure stratification of the photosphere
• A quasi-biennial variation of sunspot magnetic
  configurations

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Other Mid-Term Periodicities

• Solar Spectroscopic Temperature Measurements
• Solar Radius Measurements
• Sunspot and Sunspot Group Numbers
• Solar Neutrino Measurements
• Solar UV Measurements
• Solar Irradiance Measurements
• Shear Oscillation of the Solar Tachocline
• Solar Wind Speed
• aa-Index of Geomagnetic Activity
• The Quasi-Biennial Oscillation in the Earth
  Tropical Stratosphere

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QBO in the Tropical Stratosphere
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Composite Irradiance Data
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10 Months Moving Average of Irradiance Residuals