Seasonal temperatures over Italy and their relationship with low-frequency atmospheric circulation patterns

Abstract

An analysis of Italian seasonal temperatures from 1961 to 2006 was carried out, using homogenized data from 49 synoptic stations well distributed throughout Italy. The results show remarkable differences among seasons. Stationarity characterizes winter series, except for Northern Italy (where a warming trend from 1961 is identified); a positive trend over the entire period is recognized for spring series. Summer series are marked by a negative trend until 1981 and by a positive trend afterwards; finally, autumn series show a warming starting from 1970. The relationship between seasonal temperatures and four teleconnection patterns (North Atlantic Oscillation, East Atlantic Pattern, Scandinavian Pattern and Arctic Oscillation) influencing European climate was investigated through Spearman rank correlation and composites. Among the results, the strong linear correlation with the East Atlantic Pattern in all seasons but autumn is remarkable; moreover, the explained variance varies between 31.9% and 50.4% (leaving out autumn). Besides these four atmospheric patterns the role of other factors (e.g. soil moisture) is not dealt with, but their importance and the need for more investigation is pointed out.

Influence of atmospheric modes of variability on a deep lake south of the Alps

“…A few recent papers have demonstrated a strong influence of the EA on the air− sea heat exchange and temperature over the Medi terranean regions (deCastro et al 2008, Schroeder et al 2010, Josey et al 2011), whereas Toreti et al (2010) found a strong relationship between air temperatures and the EA all over Italy. The impact of the EMP on precipitation extremes over Cyprus has been studied by Hatzaki et al (2008).…”

Spatial analysis of mean temperature trends in Spain over the period 1961–2006

“…Several authors have carried out temperature trend analysis at different spatial scales, for instance: Schönwiese and Rapp (1997), Parry (2000), Klein Tank et al (2002), Klein Tank and Können (2003), Klein Tank et al (2005), Luterbacher et al (2004), and Moberg et al (2006) for all Europe or Brunetti et al (2000Brunetti et al ( , 2004Brunetti et al ( , 2006, Toreti and Desiato (2008), and Toreti et al (2010) in Italy; Degirmendžić et al (2004) in Poland; Rebetez and Reinhard (2008) in Switzerland; Wulfmeyer and Henning-Müller (2006) in Germany; Chaouche et al (2010) in France;and Feidas et al (2004) in Greece. Although there are local and regional differences most of Europe has experienced rising temperatures of about 0.8°C during the 20th century (IPCC, 2001) showing similar patterns to the global or a hemispheric scale.…”

Change-point analysis for serially correlated summit temperatures in the Romanian Carpathians

“…1. We have analyzed only mean summer temperatures (even though temperature data are available at each month and season of the year) because large-scale climate changes appear to be most articulated during the summer months (e.g., (Toreti et al 2010;Croitoru et al 2011)). …”

“…The model discussed in Lund and Reeves (Lund and Reeves 2002) and Toreti et al (Toreti et al 2010) proposes to obtain an estimated value for the change point c by maximizing an F statistic. To determine if the change is statistically significant (i.e., a true change point), Lund and Reeves (Lund and Reeves 2002) compared the observed max F statistic with critical values obtained by simulation under a null hypothesis of "no change" at c (see (Lund and Reeves 2002) for more details).…”