What is wavelet analysis of drought, and dominant periodicity?
In short: wavelet analysis decomposes a drought-index time series into time–frequency space, showing how the strength of different cycles changes through time. The dominant periodicity is the cycle length that carries the most power — for example a 2–4-year band often linked to the El Niño–Southern Oscillation. It helps connect drought variability to large-scale climate oscillations. DMAP V2.1 includes wavelet analysis and identifies the dominant periodicity of your drought index.