A multivariate regional test for detection of trends in extreme rainfall: the case of extreme daily rainfall in the French Mediterranean area

Abstract. In this paper we present a multivariate regional test we developed for the detection of trends in extreme rainfall, which takes into account the spatial dependence between rainfall measurements with copula functions. The test is based on four steps. It was applied to a set of 92 series of Annual Daily Maxima (ADM) rainfall in the French Mediterranean area, sampled during the 1949–2004 observation period. The results show a low significant trend, concerning mainly the mountains area in the west part of the French Mediterranean region. The position's parameters of the ADM rainfall probability distribution functions present a low but significant increasing trend of about 5% to 10%, the same increase as that observed in ADM rainfall quantiles in the last 56 years. Further work is needed to understand if this significative trend is related to the global climate change or to the natural variability of Mediterranean climate.