Solar activity in connection with a 2.5 years periode cycle in air temperature time series using the Morlet wavelet method

The Morlet wavelet is applied to air temperature time series obtained from several
weather stations and reveals the existence of a period cycle of 20-30 months since
1950, with an estimated amplitude of 0.5 C. The origin of this period is investigated
by computing the scale spectra associated to the principal indices that characterize
air mass flows in the troposphere and the stratosphere, as well as the signals related
to the sunspot number and the solar flux. Each analysed signal shows this period of
approximatively 2.5 years. This suggests that the 2.5 years-cycle could be resulted
from the solar activity.