Precipitation cycles in Turkey

Turkey is located in the temperate zone; thus, it is influenced by regionally different air masses during summers and winters, resulting in different precipitation regimes. Often, systems with varying masses of air repeatedly affect Turkey; however, at times, these periods are disrupted and difficult to predict. This study analyzes whether a certain periodicity exists in the seasonal and annual total precipitation of 74 meteorological stations in Turkey using periodograms. The analyses conducted herein showed more than one period in the series; therefore, this study was extended, and the first six periods were examined. As a result, we found 2-, 3-, 4-, and 5-year precipitation cycles (PCs) in the short term; 6-, 7-, and 8-year PCs in the medium term; and 11-, 12-, 14-, 17-, and 21-year PCs in the long term in Turkey’s PC. While seasonal distributions exhibited similarities, there were significant differences in the seasonal frequencies owing to seasonal variations in the systems affecting Turkey. The cycles vary by region, and some of these cycles can be found in each region. Three cycles have been identified in Turkey according to frequency and length, namely: (1) short-term cycle across Turkey; (2) Eastern and Central Anatolia, the Black Sea, and Aegean regions; and (3) borders of Central Anatolian and the eastern Mediterranean region. A cluster identifies unrelated locations as the affected local factors. Cycles are connected to the NAO, whereas solar activity is observed throughout Turkey. The analysis showed that certain cycles were repeated and were not dominant in each period, with the best example of this cycle as the 7–14–21 consecutive cycles.