Post on 16-Jan-2016
description
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
27-day solar cycle
11-year solar insolation: 0.1%
11-year Lyman-: 50%
27-day UV (200-300 nm): 0.23%
27-day Lyman-: 5%
COSMIC occultations in 24 hrs
(Illustration by Bill Schreiner, UCAR.)
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
Liang et al. (2008)
Daily mean5-day running mean15-day running mean
27-day FFT54-day FFT10.7-cmLyman-alpha
13.5-day FFTLyman-alpha
355 kmTropics
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
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
FFT of atmospheric temperature35 mbar22.5N
281 mbartropics
Lyman-
F10.7 cm
Liang et al. (submitted)
Liang et al. (submitted)
Latitudinal profiles
35 mbar
281 mbar
Liang et al. (submitted)
Vertical profile at low latitudes
Liang et al. (submitted)
Further verification
NCEP2COSMIC+FFTCOSMIC+EMDAIRS+FFT
Liang et al. (submitted)
CMD of COSMIC and MLS data
Li et al. (submitted)
MLS
COSMIC
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)
Thanks you!
Comments?
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