2014

Seasonality of Precipitation in Turkey: Past, Present and Future Assessments

The objective of this study is to analyze seasonality of precipitation using circular statistics method apart from the other methods in the literature and to investigate changes in seasonality in the future projections. The non-parametric circular statistical method is used to analyze seasonality of precipitation over Turkey for past (1956-1975) and present (1986-2005) periods using both station data and gridded observation data (CRU-3.24). This method is also applied to the CORDEX Europe domain for three different periods which cover early century (2016-2035), mid-century (2046-2065) and end-century (2081-2099) to investigate the potential future changes in the seasonality under a pessimistic climate scenario, CMIP5-RCP 8.5 (Coupled Model Intercomparison Project phase 5-Representative Concentration Pathways 8.5). Seasonality Index (SI) over Turkey decreases from south (~0.6) to north (~0.1) for past and present periods. For the future periods, SI tends to increase in the south, especially in the south-eastern Anatolian region, while it tends to decrease over the Black Sea and central Anatolian regions. Beside SI, another outcome from the circular statistics is the average occurrence time of precipitation during a year. Winter months (December-January-February) are common occurrence time of precipitation in general for past and present periods. Precipitation occurrence time for the future periods does not change much in the future periods for most of the regions except for the central Black Sea and southeastern Anatolia where it shifts to October and November, respectively.

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