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Presence of quasi 27-day oscillations in the atmosphere

Presence of quasi 27-day oscillations in the atmosphere. Mao-Chang Liang (Academia Sinica and NCU) K. Fai Li, and Yuk L. Yung (Caltech) European Geosciences Union General Assembly 2009 Vienna, Austria, 19 – 24 April 2009. 11-year solar insolation: 0.1% 11-year Lyman- : 50%.

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Presence of quasi 27-day oscillations in the atmosphere

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  1. Presence of quasi 27-day oscillations in the atmosphere Mao-Chang Liang (Academia Sinica and NCU) K. Fai Li, and Yuk L. Yung (Caltech) European Geosciences Union General Assembly 2009 Vienna, Austria, 19 – 24 April 2009

  2. 11-year solar insolation: 0.1% 11-year Lyman-: 50% 27-day UV (200-300 nm): 0.23% 27-day Lyman-: 5% 27-day solar cycle

  3. COSMIC occultations in 24 hrs (Illustration by Bill Schreiner, UCAR.)

  4. FORMOSAT-3/COSMIC mission • Launch on April 14, 2006 • 6 satellites orbiting at ~800 km • 3 instruments • GPS radio occultation receiver • Tiny ionospheric photometer • Triband beacon • 1.7M (neutral) and 1.9M (ionized) soundings (2008.114) • ~1500 soundings per day

  5. 355 km Tropics Daily mean 5-day running mean 15-day running mean 27-day FFT 54-day FFT 10.7-cm Lyman-alpha 13.5-day FFT Lyman-alpha Liang et al. (2008)

  6. Methods • Daily and zonally averaged in 36 latitude bins • 30 layers from 1-1000 mbar • Traditional Fourier transform, with Hanning window of 20-25 (10-20) days and 35-40 (40-50) days • Empirical mode decomposition • 27-day mainly in mode #4, sometime leak to mode #3 • 13.5-day mainly in model #3 • EMD to remove long periods followed by FFT • Running mean window of 60 days • CMD & Wavelet

  7. Methods • Daily and zonally averaged in 36 latitude bins • 30 layers from 1-1000 mbar • Traditional Fourier transform, with Hanning window of 20-25 (10-20) days and 35-40 (40-50) days • Empirical mode decomposition • 27-day mainly in mode #4, sometime leak to mode #3 • 13.5-day mainly in model #3 • EMD to remove long periods followed by FFT • Running mean window of 60 days • CMD & Wavelet

  8. FFT of atmospheric temperature 35 mbar 22.5N Lyman- F10.7 cm 281 mbar tropics Liang et al. (submitted)

  9. Liang et al. (submitted)

  10. Latitudinal profiles 35 mbar 281 mbar Liang et al. (submitted)

  11. Vertical profile at low latitudes Liang et al. (submitted)

  12. Further verification NCEP2 COSMIC+FFT COSMIC+EMD AIRS+FFT Liang et al. (submitted)

  13. CMD of COSMIC and MLS data MLS COSMIC Li et al. (submitted)

  14. Summary and Future work • Presence of quasi 27-day signals in the atmosphere is established • A likely source is solar forcing • A potentially useful tool for calibrating climate models • Analyzing WACCM3 (0-150 km)

  15. Thanks you! Comments?

  16. Solar forcing • >>10 kyr of precession, obliquity, eccentricity • 70-2300 years cycle • 22-year magnetic field cycle • 11-year sunspot cycle • Annual cycle • 27-day cycle • Diurnal cycle

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