\label{fig:periodogram}
Temporal average (1979--2014) periodograms for the meridional average (10$^{\circ}$S to 10$^{\circ}$N) 500 hPa rotated meridional wind anomaly (wind values outside of 115$^{\circ}$E to 235$^{\circ}$E were set to zero). Each curve represents a different running mean window that was applied to the daily timescale data prior to the analysis. The vertical axis units correspond to Equation \ref{eq:variance_explained}.