Rainfall data analysis using wavelet transform.
Celso Augusto Guimarães Santos, Carlos de Oliveira Galvão, Ricardo Machado Trigo · IAHS-AISH publication · 2003
An application of wavelet analysis is done with a long time series of the total monthly rainfall from several places from different regions of the world (i.e. Iberian Peninsula, Japan and north-eastern Brazil). Such an analysis was performed in order to fully characterize the distinct time-frequency rainfall variability observed in each of these areas. Besides the rainfall variability analysis, the main frequency components in the time series are studied by the global wavelet spectrum, revealing how the monthly rainfall frequency of each place is composed. This analysis is considered to be more accurate than the standard Fourier analysis. The modulation in separated bands was done in order to extract additional information; e.g. the 8-16-month band was examined by an average of all scales between 8 and 16 months, giving a measure of the average monthly variance versus time, where the periods with low or high variance could be identified.