Monthly rainfall changes in Central and Western Mediterranean basins, at the end of the 20th and beginning of the 21st centuries

Abstract

ABSTRACT:Changes in the statistical distribution of rainfall amounts have been studied in four Mediterranean regions: the French and Spanish Mediterranean coasts, Sardinia Island, and the Calabrian region, in Italy. The largest precipitation series (from 70 to 150 years) in these zones have been collected and studied at yearly and monthly time scales by means of different parametric and nonparametric techniques. Nonparametric procedures have focussed on continuous time series changes, while possible changes at the end of the 20th century have been studied developing a parametric method. Among the results obtained, the 1984/1985 to 1994/1995 and 1994/1995 to 2004/2005 decades have been revealed as some of the driest ones since data are available in central and western Mediterranean. Despite that, such a finding is not always accompanied with a trend in the entire rainfall series. On the one hand, the low precipitation amounts detected in Central Mediterranean are caused in its major contribution by a diminution of the winter rainfall. On the other hand, a diminution of the spring and winter rainfall is the cause of the driest records since data are available in Western Mediterranean. Possible relations between the dry records and seasonal SLP-based indexes have been studied. The seasonal configurations of the North Atlantic Oscillation (NAO) have been calculated and their time series have provided a good perspective on the evolution of the most contributive synoptic patterns to climate variability at the region. The high frequency of positive seasonal phases of winter, spring and autumn NAO at the end of the 20th century and beginning of the 21st have been found as possible dynamic mechanism causing the last decades dryness. Moreover, moving correlations suggest a strengthening in the correlation between those seasonal NAOs and precipitation anomalies in Central and Western Mediterranean.

Evolving flood patterns in a Mediterranean region (1301–2012) and climatic factors – the case of Catalonia

“…5). These results match the increase in precipitation in August in the city, with a significant value of +2.73 mm yr −1 for the 1850-1984 period, as shown by Altava-Ortiz et al (2010).…”

The viticultural system and climate change: coping with long-term trends in temperature and rainfall in Roussillon, France

“…Observed and simulated changes in precipitationAlthough we do not present the data here, the analysis of daily precipitation data over the period 1925-2010 does not show significant trends in annual accumulation for Roussillon, a result consistent with other studies on the Western Mediterranean basin(Brunetti et al 2004(Brunetti et al , 2006Gonzalez- Hidalgo et al 2009;Altava-Ortiz et al 2011;Camuffo et al 2012). Seasonal patterns are variable intra-annually but remain relatively stable inter-annually, even if some recent changes have been detected.…”

Flash floods in Catalonia: a recurrent situation

“…The monthly analysis corroborates the strong summer contribution to this evolution; in fact, the highest positive trend has been found for September (6 floods/century), followed by August (4 floods/century) and July (3 floods/century), while October showed a negative trend and the rest of the year did not show any trend. Summer rainfall evolution does not experience any regional trend, although we must recognize the period 1994-2003 as the driest decade in the last century (Altava-Ortiz et al, 2010). The analysis of monthly rainfall evolution for some stations located on the coast (Llasat et al, 2009b) as well as the analysis of daily precipitation maxima corroborate this lack of trend (Barrera et al, 2006).…”