The quasi-decadal modulation of running correlations involving the QBO

ANA G. ELIAS; MARTA ZOSSI DE ARTIGAS

JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS

Elsevier Ltd.

Lugar: Oxford, UK; Año: 2006 vol. 68 p. 1980 - 1986

1364-6826

Running correlations between "ideal" periodic sine series, u(t) and y(t),are analyzed in the present work, which, in this case, results in a kind of beating of the two waves. u(t) is considered as a quasi-biennial periodic function standing for an idealized quasi-biennial oscillation (QBO). The beat frequency in the running correlation coefficient series will correspond to a decadal oscillation if periodicities in y(t) are around 0.6-0.8 years greater or 0.4-0.5 years smaller than u(t) period. The periodicities required by y(t) to generate a decadal variation in the running correlation with u(t), may appear in series associated to the 11-year solar activity cycle due to its asymmetry: solar activity rises to maximum levels faster than it falls to minimum levels. Therefore, running correlations between the stratosphere QBO and time series with a biennial or triennial oscillation, associated or not to the solar cycle, could present a decadal oscillation due merely to the statistics involved. Taking into account the idealization of the series considered, without any relationship or interaction between them, neither a decadal modulation in u(t), we obtain a quasi-decadal oscillation in running correlations, as that obtained when certain empirical data series are correlated with the QBO in the stratosphere.