Climate, Climate Variability and Impacts in the Mediterranean Area: An Overview
11
May and October at average temperatures of 15 cc, Minimum precipitation occurs
in July (9 mm) at 24 'c accompanied by south-easterly winds, especially during
nighttime, and the winter rain is of the order of 26 mm/month at temperatures of 5
C accompanied by westerly winds. In a distance of only 120 km to the north, in
Cuenca (955 m) at the fringe of a mountainous range, the rainfall lies between 40
and 70 mm/month at temperatures between 3 and 13C during most of the year.
Only in July and August the precipitation drops to 20 mm at temperatures of22C.
Total precipitation lies between 322 mm (1918) and 984 mm (1933). Mostly
westerly winds blow all over the year except during nighttime in summer and
autumn with low speed. 215 km to the north-west of Albacete, in Toledo (551 m),
winds and the Mediterranean influence are much weaker than at the other two
stations, in July and August 10 mm precipitation is measured per month when the
temperatures are at 26C, In summer the air is much drier than at the other stations.
Most of the rain (30 - 40 mm/month) falls during the rest of the year with totals
between 191 (1950) and 575 mm/year (1955).
A number of studies have been made during recent years to assess the variability
of the Mediterranean climate and synergies between the different parts of the basin.
Because of its overriding importance for the vegetation, major attention is focussed
here on the precipitation regime. Goossens (1985) applied a principal component
analysis on a large set of data and found five different rainfall regimes in the
European part of the Mediterranean:
• In the north-west of Spain, northern Portugal, northern Italy and the eastern part
of the Mediterranean France rainfall exceeds 700 mm more or less equally
distributed over the year.
In the north-east and south of Spain, southern Portugal, and the western
Mediterranean part of France the rainfall is mainly during the winter half-year
and very little rain (50 mm) falls during summer.
• On the Balearic Islands, in the central part of Italy, northern Greece, and part of
the former area of Yugoslavia precipitation falls mostly during winter but the
summer is not without rain: 80 mm in the northern parts of this region but
amount and duration progressively decreasing towards 20 mm in the south.
In the south-east of Italy, Croatia, Serbia, and Albania occurs a single
precipitation maximum in winter while the summer is almost but not completely
rainless (e.g. Tirane 150 mm). This, in fact, is the area of highest annual
precipitation (Crkvice: 4600 mm).
Considerably less precipitation falls in other regions of dry and dusty lands
throughout the long summer, e.g. Athens 14 mm, Hiraklion 3.2 mm, the
Marathon area with 5-10 mm in both July and August according to Amanatidis
et al. (1993).
Corte-Real et al. (1995) went one step further by correlating atmospheric
circulation anomalies in the 500 hPa respectively sea-level pressure fields with
monthly mean temperature and rainfall. The pattern of the canonical correlation
analysis between the large scale pressure anomalies and the temperature anomalies
are more coherent than those with precipitation. This indicates that the precipitation
11
May and October at average temperatures of 15 cc, Minimum precipitation occurs
in July (9 mm) at 24 'c accompanied by south-easterly winds, especially during
nighttime, and the winter rain is of the order of 26 mm/month at temperatures of 5
C accompanied by westerly winds. In a distance of only 120 km to the north, in
Cuenca (955 m) at the fringe of a mountainous range, the rainfall lies between 40
and 70 mm/month at temperatures between 3 and 13C during most of the year.
Only in July and August the precipitation drops to 20 mm at temperatures of22C.
Total precipitation lies between 322 mm (1918) and 984 mm (1933). Mostly
westerly winds blow all over the year except during nighttime in summer and
autumn with low speed. 215 km to the north-west of Albacete, in Toledo (551 m),
winds and the Mediterranean influence are much weaker than at the other two
stations, in July and August 10 mm precipitation is measured per month when the
temperatures are at 26C, In summer the air is much drier than at the other stations.
Most of the rain (30 - 40 mm/month) falls during the rest of the year with totals
between 191 (1950) and 575 mm/year (1955).
A number of studies have been made during recent years to assess the variability
of the Mediterranean climate and synergies between the different parts of the basin.
Because of its overriding importance for the vegetation, major attention is focussed
here on the precipitation regime. Goossens (1985) applied a principal component
analysis on a large set of data and found five different rainfall regimes in the
European part of the Mediterranean:
• In the north-west of Spain, northern Portugal, northern Italy and the eastern part
of the Mediterranean France rainfall exceeds 700 mm more or less equally
distributed over the year.
In the north-east and south of Spain, southern Portugal, and the western
Mediterranean part of France the rainfall is mainly during the winter half-year
and very little rain (50 mm) falls during summer.
• On the Balearic Islands, in the central part of Italy, northern Greece, and part of
the former area of Yugoslavia precipitation falls mostly during winter but the
summer is not without rain: 80 mm in the northern parts of this region but
amount and duration progressively decreasing towards 20 mm in the south.
In the south-east of Italy, Croatia, Serbia, and Albania occurs a single
precipitation maximum in winter while the summer is almost but not completely
rainless (e.g. Tirane 150 mm). This, in fact, is the area of highest annual
precipitation (Crkvice: 4600 mm).
Considerably less precipitation falls in other regions of dry and dusty lands
throughout the long summer, e.g. Athens 14 mm, Hiraklion 3.2 mm, the
Marathon area with 5-10 mm in both July and August according to Amanatidis
et al. (1993).
Corte-Real et al. (1995) went one step further by correlating atmospheric
circulation anomalies in the 500 hPa respectively sea-level pressure fields with
monthly mean temperature and rainfall. The pattern of the canonical correlation
analysis between the large scale pressure anomalies and the temperature anomalies
are more coherent than those with precipitation. This indicates that the precipitation