Some aspects of the latitudinal momentum transport by Reynolds stresses, as deduced from the analysis of the Greenwich sunspot data for the period 1874-1976 by using only very young sunspot groups (age less-than-or-equal-to 3 d), were investigated in order to study the equatorial acceleration maintenance and its possible correlations with the equatorial angular velocity time variations and the solar cycle. The results, which are consistent with those of previous authors, indicate the presence of a net angular momentum flux towards the equator which is more vigorous at higher latitudes, and sufficient on average to maintain the observed equatorial acceleration. The angular momentum transport time variations show a significant periodicity correlated with the solar cycle. Also the equatorial velocity time variations show significant periodicities, which in turn may depend on the angular momentum transport time variations. The scenario which emerges from these results is discussed in the framework of the theories of differential rotation and activity cycle.
ANGULAR-MOMENTUM TRANSPORT BY REYNOLDS STRESSES DETERMINED FROM THE ANALYSIS OF 100-YEAR SUNSPOT MOTIONS AND ITS VARIATIONS WITH SOLAR-CYCLE
ZUCCARELLO, Francesca
1991-01-01
Abstract
Some aspects of the latitudinal momentum transport by Reynolds stresses, as deduced from the analysis of the Greenwich sunspot data for the period 1874-1976 by using only very young sunspot groups (age less-than-or-equal-to 3 d), were investigated in order to study the equatorial acceleration maintenance and its possible correlations with the equatorial angular velocity time variations and the solar cycle. The results, which are consistent with those of previous authors, indicate the presence of a net angular momentum flux towards the equator which is more vigorous at higher latitudes, and sufficient on average to maintain the observed equatorial acceleration. The angular momentum transport time variations show a significant periodicity correlated with the solar cycle. Also the equatorial velocity time variations show significant periodicities, which in turn may depend on the angular momentum transport time variations. The scenario which emerges from these results is discussed in the framework of the theories of differential rotation and activity cycle.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.