Spatial and Temporal Variations in Precipitation and Aridity Index Series of Turkey
189
Central Anatolia region, especially over the Konya sub-region. Zonality of the longterm mean precipitation totals is most pronounced for winter (TUrke~, 1998a).
Mean winter precipitation decreases from coastal belts to interiors by varying
from above 650 mm along the eastern Black Sea and the western Mediterranean to
below 100 mm over continental Central Anatolia and Eastern Anatolia regions (Fig.
4a). The western Mediterranean sub-region is the most rainy area of Turkey in winter,
with about 754 mm mean precipitation total at the Manavgat station. High
precipitation amounts along the Black Sea and the Mediterranean coastal zones are
associated mainly with the North-eastern Atlantic originated mid-latitude depressions
and the Mediterranean depressions, respectively (TUrke~, 1998a). Orographic rains
on the windward slopes of the Taurus Mountains and the Northern Anatolia
Mountains also contribute to increase of the precipitation amounts.
Mean spring precipitation amounts range from below 150 mm over the Aegean
coast with the northern Marmara and the Continental Central Anatolia connected with
the middle Mediterranean coast to above 300 mm on the eastern Black Sea coast and
the south-east corner of the country (Fig. 4b). Most ofthe country gets a precipitation
ranging from below 150 mm to about 200 mm in spring. In addition to the frontal
rains, higher precipitation amounts over the wetter areas with a 200-350 mm mean
are attributed to high topography and their exposures to the dominant air streams, and
the local convective activities, respectively (TUrke~, 1998a). Summer rainfall amounts
increase from below 5 mm over the Syrian border to above 450 mm on the eastern
Black Sea sub-region of Turkey (Fig. 4c). Approximately half of the country receives
a mean rainfall less than 50 mm in summer. Higher summer rainfall over the eastern
Black Sea and the high north-eastern Anatolia is related closely with the post-frontal
and orographically induced rainfall in addition to the frontal rains. Mean autumn
precipitation totals generally decrease from coastal areas to interiors, as in winter
(Fig. 4d). Eastern Black Sea is the wettest area, with about 795 mm seasonal mean
precipitation at the Rize station. Precipitation amounts of about 100 mm cover much
of the country, particularly continental interiors. With respect to amount and
distribution pattern of precipitation, the mean autumn precipitation is quite similar to
mean winter precipitation over the Black Sea region, with a strong gradient along the
Northern Anatolia Mountains. Mean autumn precipitation over the Mediterranean
rainfall region differ from winter precipitation, because the Mediterranean type
frontal cyclones are not so active in autumn yet as much as in winter.
4.1.3 Seasonality of Precipitation
Maps for the geographical distribution of percentage contribution of mean seasonal
precipitation amounts to mean annual total are shown in Fig. 5. Precipitation is more
seasonal over the western and southern regions of Turkey, with a winter maximum
above 40 per cent, whereas it is generally uniform over the Black Sea region (Fig.
5a). Spring precipitation contributes more than 30 per cent of the annual total over
most of the continental interiors (Fig. 5b). In summer, maximum precipitation is
concentrated over the north-eastern Anatolia, while the minimum occurs over the
southern parts of the Continental Mediterranean region, with less than 5 per cent of
the annual total (Fig. 5c). Contribution of the autumn precipitation is above 30 per
189
Central Anatolia region, especially over the Konya sub-region. Zonality of the longterm mean precipitation totals is most pronounced for winter (TUrke~, 1998a).
Mean winter precipitation decreases from coastal belts to interiors by varying
from above 650 mm along the eastern Black Sea and the western Mediterranean to
below 100 mm over continental Central Anatolia and Eastern Anatolia regions (Fig.
4a). The western Mediterranean sub-region is the most rainy area of Turkey in winter,
with about 754 mm mean precipitation total at the Manavgat station. High
precipitation amounts along the Black Sea and the Mediterranean coastal zones are
associated mainly with the North-eastern Atlantic originated mid-latitude depressions
and the Mediterranean depressions, respectively (TUrke~, 1998a). Orographic rains
on the windward slopes of the Taurus Mountains and the Northern Anatolia
Mountains also contribute to increase of the precipitation amounts.
Mean spring precipitation amounts range from below 150 mm over the Aegean
coast with the northern Marmara and the Continental Central Anatolia connected with
the middle Mediterranean coast to above 300 mm on the eastern Black Sea coast and
the south-east corner of the country (Fig. 4b). Most ofthe country gets a precipitation
ranging from below 150 mm to about 200 mm in spring. In addition to the frontal
rains, higher precipitation amounts over the wetter areas with a 200-350 mm mean
are attributed to high topography and their exposures to the dominant air streams, and
the local convective activities, respectively (TUrke~, 1998a). Summer rainfall amounts
increase from below 5 mm over the Syrian border to above 450 mm on the eastern
Black Sea sub-region of Turkey (Fig. 4c). Approximately half of the country receives
a mean rainfall less than 50 mm in summer. Higher summer rainfall over the eastern
Black Sea and the high north-eastern Anatolia is related closely with the post-frontal
and orographically induced rainfall in addition to the frontal rains. Mean autumn
precipitation totals generally decrease from coastal areas to interiors, as in winter
(Fig. 4d). Eastern Black Sea is the wettest area, with about 795 mm seasonal mean
precipitation at the Rize station. Precipitation amounts of about 100 mm cover much
of the country, particularly continental interiors. With respect to amount and
distribution pattern of precipitation, the mean autumn precipitation is quite similar to
mean winter precipitation over the Black Sea region, with a strong gradient along the
Northern Anatolia Mountains. Mean autumn precipitation over the Mediterranean
rainfall region differ from winter precipitation, because the Mediterranean type
frontal cyclones are not so active in autumn yet as much as in winter.
4.1.3 Seasonality of Precipitation
Maps for the geographical distribution of percentage contribution of mean seasonal
precipitation amounts to mean annual total are shown in Fig. 5. Precipitation is more
seasonal over the western and southern regions of Turkey, with a winter maximum
above 40 per cent, whereas it is generally uniform over the Black Sea region (Fig.
5a). Spring precipitation contributes more than 30 per cent of the annual total over
most of the continental interiors (Fig. 5b). In summer, maximum precipitation is
concentrated over the north-eastern Anatolia, while the minimum occurs over the
southern parts of the Continental Mediterranean region, with less than 5 per cent of
the annual total (Fig. 5c). Contribution of the autumn precipitation is above 30 per