Figure 4.

Cross-wavelet coherency and phase of Plasmodium falciparum malaria rate with A temperature and B rainfall and of P. vivax malaria rate with C temperature and D rainfall. The coherency scale is from zero (blue) to one (red). Red regions in the upper part of the plots indicate frequencies and times for which the two series share variability. The cone of influence (within which results are not influenced by the edges of the data) and the significant (p < 0.05) coherent time-frequency regions are indicated by solid lines. The colors in the phase plots correspond to different lags between the variability in the two series for a given time and frequency, measured in angles from -PI to PI. A value of PI corresponds to a lag of 17 mo. The procedures and software are those described in [31,32]. A smoothing window of 15 mo (2w + 1 = 31) was used to compute the cross-wavelet coherence.