An Advanced Review of the Relationships between Sahel Precipitation and Climate Indices: A Wavelet Approach
Figure 5
Cross wavelet spectrum (left) and wavelet coherence (right) between GPCP Sahel precipitation (east and west) and selected climate indices (ENSO and IOD). (a)-(b) Western Sahel rainfall and ENSO, (c)-(d) eastern Sahel Rainfall and ENSO, (e)-(f) western Sahel rainfall and IOD, and (g)-(h) eastern Sahel rainfall and IOD. In-phase, pointing right; anti-phase, pointing left; and leading by 90∘ pointing straight down; (see text for details and interpretation). The thick contour enclosed regions are greater than 95% confidence for a red-noise process. The thin solid line indicates the “cone of influence,” where edge effects become important.
