Defining and characterizing high-rainfall Mediterranean climates

Abstract

The world's five Mediterranean-climate regions are typified by similarities in climate reflected in structural vegetation patterns. We developed a methodology to define high-rainfall (annual precipitation ≥800 mm) Mediterranean climates and contrast patterns of between- and within-region climatic heterogeneity. Climatic indices describing the seasonality of the climate were computed in Geographic Information Systems and included in a numerical analysis, in addition to selected bioclimatic variables, using the pattern analysis program PATN. Selected locations from high-rainfall Mediterranean-climate regions were grouped according to climatic similarity, and within-region climatic heterogeneity was compared between regions. Areas traditionally not considered as Mediterranean-climate regions emerged in the classification. Only the Mediterranean-type systems within the Pacific north-west of North America and south-central Chile comprised a substantial extent of high-rainfall Mediterranean climate. Both of these regions were characterized by a high climatic diversity and steep topographic gradients. The numerical analysis demonstrated the high diversity of the high-rainfall Mediterranean-climate type and differences in within-region climatic heterogeneity between the world's high-rainfall Mediterranean-climate regions.