  Transient and recurrent solar activity drive geomagnetic disturbances; these
are quantified (amongst others) by DST, AE indices time-series. Transient
disturbances are related to the Interplanetary Coronal Mass Ejections (ICMEs)
while recurrent disturbances are related to corotating interaction regions
(CIR). We study the relationship of the geomagnetic disturbances to the solar
wind drivers within solar Cycle 23 where the drivers are represented by ICMEs
and CIRs occurrence rate and compared to the DST and AE as follows: terms with
common periodicity in both the geomagnetic disturbances and the solar drivers
are, firstly, detected using continuous wavelet transform (CWT). Then, common
power and phase coherence of these periodic terms are calculated from the
cross-wavelet spectra (XWT) and waveletcoherence (WTC) respectively. In
time-scales of about 27 days our results indicate an anti-correlation of the
effects of ICMEs and CIRs on the geomagnetic disturbances. The former modulates
the DST and AE time series during the cycle maximum the latter during periods
of reduced solar activity. The phase relationship of these modulation is highly
non-linear. Only the annual frequency component of the ICMEs is phase-locked
with DST and AE. In time-scales of about 1.3-1.7 years the CIR seem to be the
dominant driver for both geomagnetic indices throughout the whole solar cycle
23.
