Extreme Precipitation Events in Northeast Spain

Writing as background for their study, Begueria et al. (2011) say that "analysis of the characteristics of extreme precipitation over large areas has received considerable attention, mainly due to its implications for hazard assessment and risk management," additionally noting that "whether there are trends in extreme precipitation records is currently of major interest in climate change studies," where climate models suggest that as Earth's climate warms, various types of extreme weather phenomena will become more frequent and severe.

Working with a set of 64 daily rainfall series from 1930 to 2006 covering the region of northeast Spain, Begueria et al. employed the theory of non-stationary extreme value analysis to the data sets using the peaks-over-threshold approach, whereby "a Poisson/generalized Pareto model, in which the model parameters were allowed to vary linearly with time, was fitted to the resulting series of precipitation event's intensity and magnitude," after which "a log-likelihood ratio test was applied to determine the existence of trends in the model parameters."

According to the five researchers who conducted the study, results revealed that "statistical significance was achieved in less than 5% of the stations using a linear non-stationary model at the annual scale, indicating that three is no evidence of a generalized trend in extreme precipitation in the study area." At the seasonal scale, however, they found that "a significant number of stations along the Mediterranean (Catalonia region) showed a significant decrease of extreme rainfall intensity in winter, while experiencing an increase in spring."

After some seven and a half decades of supposedly unprecedented global warming - which climate alarmists typically claim should increase the frequency and severity of extreme weather events - the study of Begueria et al. suggests that their dire forecast has not fared very well throughout northeast Spain in the case of precipitation.