Spatial and temporal variation of precipitation density over Turkey

Spatial and Temporal Variation of Precipitation Density over Turkey -Faize SARIŞABSTRACTThe aim of this study is to analyze long-term monthly, seasonal and annual variationsand trends in the daily precipitation densities over Turkey. Precipitation amounts are alsoanalysed to explain the trends of precipitation density correctly. Kruskall-Wallishomogeneity test is used to detect non-homogeneity in the data. Amounts of theprecipitation densities are calculated by taking rates of the monthly, seasonal and annualprecipitation amounts with the time duration of the rainy days in the related month, seasonand year. Long-term trends in monthly, seasonal and annual precipitation andprecipitation density amounts are obtained by employing the methods of Mann-Kendall (M-K) rank correlation and least square linear regression. Important findings which areobtained from employing trend methods can be summarized as follows: (1) A decreasingtrend is determined in annual precipitations and precipitation density, this trend is verystrong in Mediterranean and Black Sea precipitation regime regions; (2) A decreasingtrend in winter precipitations but an increasing trends in spring, summer and autumnprecipitation are determined; (3) There is a decreasing trend in precipitation density in allseasons and this trend is statistically more significant than the trends in precipitation; (4)The results of trend analysis of precipitation and precipitation densities showed a perfectharmony in winter season; (5) Decreasing trend in winter precipitations is the strongest inMediterranean and decreasing trend in winter precipitation density is the strongest in BlackSea precipitation regime regions; (6) It is observed that the decreasing trend inprecipitation density is getting stronger in period after the year of 1950. In this study, sameresults are obtained with the results of previous studies that are made before for Turkey.Strong decreasing trends in winter precipitation?s and increasing trend in non-heavyprecipitations over Turkey are harmonious findings with results of this study. It isnecessary to research the effect of precipitation density in constitution of extreme eventsover the Mediterranean and Black Sea and to explain the connection between decreasingtrend of precipitation density and drought for further research.