30 and 43 months period cycles found in air temperature time series using the Morlet wavelet

A wavelet-based methodology is applied to relevant climatic indices and air temperature records and
allow to detect the existence of unexpected cycles. The scale spectrum shows the presence of two cycles of about
30 and 43 months, respectively, in the air–temperature time series, in addition to the well-known cycles of 1 day
and 1 year. The two cycles do not affect the globe uniformly: some regions seem to be more influenced by the
period of 30 months (e.g. Europe), while other areas are affected by the period of 43 months (e.g. North-West of the USA). Similar cycles are found in the indices and the regions influenced by these indices: the NAO index and the Western Europe display a cycle of 30 months, while the cycle of 43 months can be found in the ENSO index and in regions where it is known to have an impact.