R. Tomozeiu et al., Detection of changes in the summer precipitation time series of the regionEmilia-Romagna, Italy, THEOR APP C, 67(3-4), 2000, pp. 193-200
The main characteristics of the spatial and temporal variability of summer
precipitation observed in 40 rainfall stations of the Emilia-Romagna region
in northern Italy, are analysed for the period 1922 to 1995. Non-parametri
c tests and Empirical Orthogonal Function (EOF) analysis were used as tools
in order to achieve the paper's objective. The Pettitt and Mann-Kendall te
sts detect shift points and trends in the precipitation time series, respec
tively, while the EOF analysis reveals the main characteristics of spatial
variability. The Standard Normal Homogeneity Test (SNHT) was used to detect
the inhomogeneity of the data set.
Almost all stations exhibit an increasing trend with a systematic significa
nt upward shift around 1962. The climate signal is more significant in the
north-western, central and north-eastern part of the region, and the spatia
l extension strongly depends on the network density and the time period ana
lysed. The change in summer precipitation is mainly due to a change during
August and is confirmed by the SNHT test which does not reveal an inhomogen
eity in the series.
The first EOF pattern indicates that a common large-scale process could be
responsible for summer precipitation variability in the Emilia-Romagna regi
on. The second EOF pattern shows an opposite sign of climate variability be
tween north-western and south-eastern areas. The Apennine mountains show th
e largest climate variability in the summer precipitation field.