Meteorological Drought in Turkey: A Historical Perspective, 1930-–93

The climate of Turkey, which is mainly characterized by the Mediterranean macro climate, results from the seasonal alternation of frontal depressions with polar air masses and subtropical high pressures with subsiding maritime tropical and continental tropical air masses. Continental tropical airstreams from the northern African and Arabian deserts particularly dominate throughout the summer, by causing long-lasting warm (hot) and dry conditions over Turkey (except the Black Sea region and northeastern Anatolia). Turkey has an area of 779,452 km2 and an average elevation of 1,132 m. This study outlines some spatial and temporal characteristics of Turkey’s rainfall, particularly in terms of drought and rainfall variability for the period 1930–93. Mean characteristics of the rainfall data were investigated for 99 stations, and then variations of Turkey’s 91-station normalized rainfall series and spatial distribution of the normalized rainfall index were analyzed. Average record length of these stations is about 60 years. Approximately 67% of the countrywide annual rainfall occurs during the cold winter (40%) and cool spring (26.6%), when the eastern Mediterranean basin, Balkans, and Turkey are influenced by the frontal mid-latitude and Mediterranean depressions. Contributions of autumn and summer rainfall are about 23% and 10%, respectively, of the annual total. In area-averaged series for the Mediterranean region, winter rainfall reaches its maximum value at about 53% of the annual total, and summer rainfall declines to about 4% of the annual total. The number of stations in each rainfall regime region is given in Table 1, and the location of 99 stations is shown in Figure 1