to about 43% in the 1990s. The rate of decreasing rainfall was about 1.52 mmy
−1
and the contribution of the lower extremes to the annual rainfall also increased,
although not significantly.
Likewise, in Italy, there was a clear distinction between the heavy torrential
categories (C2, D1, D2) showing an increasing trend, and the lighter classes (A, B,
C1) showing a significant lowering trend. In this country, torrential rainfall, above
128 mmd
−1 , contributed to about 4–5% of the total rainfall in the 1990s compared
with only 1% in the 1950s. In contrast, in the 1950s heavy torrential rainfall classes
above 32 mmd
−1 accounted for only 23% of rainfall versus 32% in the 1990s.
Italian weather stations showed that heavy precipitation episodes contributed
mainly to rainfall in the summer and transition seasons. In Italy, torrential classes
D1 and D2 exhibit higher inter-annual variability among all classes.
In Israel and Cyprus, no significant trends were detected, although as in the
western Mediterranean there exist heavy categories which are C1 and C2 in Israel
and C2 and D1 in Cyprus that augment. Lighter categories like A in Israel, and B
and C1 in Cyprus show, a decreasing trend. In Israel, all classes of discrete rainfall
events have high inter-annual variability, probably due to the semi-aridity in the
south. Annual precipitation averages ranged from 776 mmy
−1 in the north to 105
mmy
−1 in the south, across a mere distance of 220 km. To some extent this may be
due to the influence of the Red Sea, which contributes to significant rainfall in the
southern region of Israel.
Alpert et al. (2002) also reported that torrential rainfall classes tend to peak in El
Nino years such as 1953, 1965, 1982/3, and 1986/7. For example, in the latter two
years, the D2 class accounted for 15% rainfall compared with the typical annual
average of 1–4%. This relationship between discrete torrential events and El Nino
has been more pronounced in recent decades as experienced in northern Israel and
Turkey. This reflects the rainfall paradox referred to above, giving high variation in
precipitation patterns in the Mediterranean Basin which may be related to greenhouse gas warming. The rain distribution is also characterized by the fact that the
increase in variance overcomes the reduction of the mean (Meehl et al. 2000).
For the period 2025–2050, matrix analysis of modeling results of temperature
and precipitation extremes was carried out by Giannakopoulos et al. (2005). It
consisted of average values under A1B, B1, and A2 scenarios of the AR4 Report,
under a conservative scenario of 2 °C average temperature increase during the
twenty-first century. The matrix showed that the east Mediterranean region
(Mashriq) was clearly the hottest and driest area, with prevailing one-month continuous period and of 2–3 continuous weeks with high summer temperature
increases of 3 and 2 °C, respectively, and with one-month continuous periods with
night temperatures increasing also by 3 °C. In Mashriq, the impact of the 2 °C
increase scenario in daily precipitation is not so drastic, with prevailing periods of
2–3 weeks and one week corresponding, respectively, to increases of 2 dry days
and decreases in 2 mm of daily precipitation.
Forecasts for North Iberian, Southern France, Corsica, Sardinia, and Sicilia
showed increased precipitation of 3 mmd
−1 in prevailing one-month continuous
periods and to rainfall decreases of 1 and 2 mmd
−1 in predominant continuous
8.6 A Brief Analysis of the Mediterranean …
299
−1
and the contribution of the lower extremes to the annual rainfall also increased,
although not significantly.
Likewise, in Italy, there was a clear distinction between the heavy torrential
categories (C2, D1, D2) showing an increasing trend, and the lighter classes (A, B,
C1) showing a significant lowering trend. In this country, torrential rainfall, above
128 mmd
−1 , contributed to about 4–5% of the total rainfall in the 1990s compared
with only 1% in the 1950s. In contrast, in the 1950s heavy torrential rainfall classes
above 32 mmd
−1 accounted for only 23% of rainfall versus 32% in the 1990s.
Italian weather stations showed that heavy precipitation episodes contributed
mainly to rainfall in the summer and transition seasons. In Italy, torrential classes
D1 and D2 exhibit higher inter-annual variability among all classes.
In Israel and Cyprus, no significant trends were detected, although as in the
western Mediterranean there exist heavy categories which are C1 and C2 in Israel
and C2 and D1 in Cyprus that augment. Lighter categories like A in Israel, and B
and C1 in Cyprus show, a decreasing trend. In Israel, all classes of discrete rainfall
events have high inter-annual variability, probably due to the semi-aridity in the
south. Annual precipitation averages ranged from 776 mmy
−1 in the north to 105
mmy
−1 in the south, across a mere distance of 220 km. To some extent this may be
due to the influence of the Red Sea, which contributes to significant rainfall in the
southern region of Israel.
Alpert et al. (2002) also reported that torrential rainfall classes tend to peak in El
Nino years such as 1953, 1965, 1982/3, and 1986/7. For example, in the latter two
years, the D2 class accounted for 15% rainfall compared with the typical annual
average of 1–4%. This relationship between discrete torrential events and El Nino
has been more pronounced in recent decades as experienced in northern Israel and
Turkey. This reflects the rainfall paradox referred to above, giving high variation in
precipitation patterns in the Mediterranean Basin which may be related to greenhouse gas warming. The rain distribution is also characterized by the fact that the
increase in variance overcomes the reduction of the mean (Meehl et al. 2000).
For the period 2025–2050, matrix analysis of modeling results of temperature
and precipitation extremes was carried out by Giannakopoulos et al. (2005). It
consisted of average values under A1B, B1, and A2 scenarios of the AR4 Report,
under a conservative scenario of 2 °C average temperature increase during the
twenty-first century. The matrix showed that the east Mediterranean region
(Mashriq) was clearly the hottest and driest area, with prevailing one-month continuous period and of 2–3 continuous weeks with high summer temperature
increases of 3 and 2 °C, respectively, and with one-month continuous periods with
night temperatures increasing also by 3 °C. In Mashriq, the impact of the 2 °C
increase scenario in daily precipitation is not so drastic, with prevailing periods of
2–3 weeks and one week corresponding, respectively, to increases of 2 dry days
and decreases in 2 mm of daily precipitation.
Forecasts for North Iberian, Southern France, Corsica, Sardinia, and Sicilia
showed increased precipitation of 3 mmd
−1 in prevailing one-month continuous
periods and to rainfall decreases of 1 and 2 mmd
−1 in predominant continuous
8.6 A Brief Analysis of the Mediterranean …
299