Temporal and spatial persistence in rainfall records from Northeast Brazil and Galicia (Spain)

Summary Temporal and spatial persistence effects in historical rainfall records are investigated for a large number of stations from Northwest Spain (Galicia) and Northeast Brazil. Quantitative results, expressed by the Hurst or roughness exponent, are obtained by two methods: the R/S analysis and the semi-variogram. Despite rather different climatic conditions and period of analysis for the two regions, the results indicate that persistence and anti-persistence for the temporal and spatial analyses, respectively, are found for both regions. Temporal persistence is known to occur with other climatic fields and in many different regions of the world. Antipersistence in spatial patterns of rainfall is a strong result of this work, despite its apparent contradiction with temporal persistence. The results for Northeast Brazil support previous indications of a geographic stratification of persistence: both temporal and spatial persistence increase as latitude decreases.