Spectral characteristics of the series of annual rainfall in England and Wales

Despite the small size of England and Wales, the rainfall there shows large variations, possibly due to geographical and topographical conditions. Spectral analysis shows a large number of periodicities, but many are statistically insignificant, indicating considerable randomness. Significant periodicities are invariably in the low periodicity region (periodicity < 5 yr). Occasionally, high periodicities are also encountered, but are always accompanied by low periodicities. Hence, meaningful predictions are not possible.