Ben-Gurion University of the Negev Jacob Blaustein Institutes for ...

10
summer it may have from to 2 to 5 months without having any significant precipitation
(Beck et al. 2006).
Temperatures during winter only occasionally reach freezing and snow only rarely
occurs at sea level. In the winter, the temperatures range from mild to very warm,
depending on distance from the sea and elevation. Even in the warmest locations,
however, temperatures usually don't reach the highest readings found in adjacent desert
regions due to cooling effect of water bodies, although strong winds (Scirocco 4 ) from
North African desert regions can sometimes boost summer temperatures. Inland
locations sheltered from or distant from sea breezes can experience severe heat during
the summer (Beck et al. 2006).
2.3 Rainfall trend in Sicily: Spatial Distribution
Historical series were analyzed using spatial analysis techniques in a GIS environment
(Piccione et al., 2008). The application was conducted using monthly data, recorded or
reconstructed from 247 rain gauge stations during the period 1931–1990.
Average annual rainfall indexes have been calculated according to the Medalus
methodology (European Commission, 1999) in two different periods (1931-1960 and
1961-1990). Figures 3 shows in dark green the spatial distribution of year precipitations
larger than 650 mm in the period 1931-1960 and figure 4 shows the same patterns in the
period 1961-90. The percentage of regional surface areas with precipitations larger than
650 mm per year decreased from 60% to 34%. Moreover, it can be seen that a great
number of stations with a statistically significant negative trend are located in the
western and south-western part of the island (Piccione et al., 2008) corresponding to the
study area.
4 Sirocco, scirocco, jugo or, rarely, siroc is a Mediterranean wind that comes from the Sahara and reaches
hurricane speeds in North Africa and Southern Europe. It is known in North Africa by the arabic word
qibli (i.e. "coming from the qibla".)