HR: 1400h
AN: A23A-06    [Abstracts]
TI: Coherence Between Periodicities of Atmospheric Teleconnection Patterns and Quasi- periodic Atmospheric and Extra-terrestrial Phenomena
AU: * Šauli, P
EM: pkn@ufa.cas.cz
AF: Institute of Atmospheric Physics ASCR, Boční II/1401, Prague 4, 14131, Czech Republic
AU: Huth, R
EM: huth@ufa.cas.cz
AF: Institute of Atmospheric Physics ASCR, Boční II/1401, Prague 4, 14131, Czech Republic
AB: We apply wavelet analysis to modes of low-frequency atmospheric circulation variability (teleconnection patterns). The modes are defined by rotated principal component analysis of monthly or 10-day mean 500 hPa heights in the Northern Hemisphere north of 20°N over 1950-2003. The uneven distribution of variance during the annual cycle is compensated for by weighting by its monthly (10-day) mean standard deviation. 13 modes are detected, most of which are active in winter. Morlet wavelet is selected as a basis for the wavelet transform. The main feature of wavelet spectra of the variability modes is their intermittency: generally, no period (within the range between 1 and 15 years) appears as dominant throughout the whole analyzed time domain. There are only a few exceptions, which have undergone stationary oscillations; e.g., 9 years for the North Atlantic Oscillation and 14 years for the Tropical / Northern Hemisphere pattern. The effects of the sampling interval (monthly or 10 day means) and of the way of compensation for the annual cycle of variability are marginal. We also calculate coherence between the wavelet spectra of the modes and those of quasi-periodic phenomena such as quasi- biennial oscillation, El Niño - Southern Oscillation, and 11-year solar cycle. Its statistical significance is determined by the Monte Carlo test. The statistically significant coherence appears, for example, between several variability modes, including the North Atlantic Oscillation, and solar activity for periods of 8 to 9 years.
DE: 0399 General or miscellaneous
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1620 Climate dynamics (0429, 3309)
SC: Atmospheric Sciences [A]
MN: 2007 Joint Assembly