The quasi-biennial oscillation in time series of solar activity parameters

ANA G. ELIAS; MARTA ZOSSI DE ARTIGAS

Solar Physics Research Trends

NOVA PUBLISHERS

Lugar: New York, Estados Unidos; Año: 2008; p. 3 - 13

Time series of solar activity parameters, such as the sunspot number Rz and the 10.7cm  solar flux F10.7, present an asymmetric quasi-decadal oscillation as their main variation. In fact, the ascending phase of the solar activity cycle is faster than the descending phase. In certain studies, a filtering process is applied to these time series in order to eliminate this main oscillation. As a consequence, a spurius quasi-biennial cycle may appear, which is the result of the filtering process. The quasi-biennial cycle thus obtained may be similar to the well-known quasi-biennial oscillation (QBO) of the stratospheric equatorial zonal winds, but with no physical association. A study is made of the character of this ?induced? quasi-biennial cycle. The results shown here do not rule out a physical origin, but point out that a result obtained after a statistical analysis carries, in addition to the physics behind, the spurious byproducts of the method applied.