  This paper describes a methodology (or treatment) to establish a
representative signal of the global magnetic diurnal variation based on a
spatial distribution in both longitude and latitude of a set of magnetic
stations as well as their magnetic behavior on a time basis. For that, we apply
the Principal Component Analysis (PCA) technique implemented using gapped
wavelet transform and wavelet correlation. The continuous gapped wavelet and
the wavelet correlation techniques were used to describe the features of the
magnetic variations at Vassouras (Brazil) and other 12 magnetic stations spread
around the terrestrial globe. The aim of this paper is to reconstruct the
original geomagnetic data series of the H-component taking into account only
the diurnal variations with periods of 24 hours on geomagnetically quiet days.
With the developed work, we advance a proposal to reconstruct the baseline for
the quiet day variations (Sq) from the PCA using the correlation wavelet method
to determine the global variation of PCA first mode. The results showed that
this goal was reached and encourage other uses of this approach to different
kinds of analysis.
