Spatiotemporal variability of precipitation concentration in western Turkey

This paper addressed the spatial and temporal variations of precipitation concentration across western Turkey, by analyzing daily and monthly precipitation time series recorded at 28 stations over the period 1966-2011. Four indices: daily precipitation concentration index (DPCI), monthly precipitation concentration index (MPCI), precipitation concentration degree (PCD) and precipitation concentration period (PCP) were used. The results showed higher values of DPCI in northwestern and southern parts and lower values in western-central, central, eastern and northeastern parts, and the southern part was the most critical part of the study area, with the highest values of DPCI, MPCI, PCD and annual total precipitation, but the lowest number of rainy days. MPCI and PCD values showed a seasonal precipitation regime over the whole study area and exhibited a pattern decreasing from southwest to northeast, which implies a more uniform distribution of monthly rainfall in a year toward the northeast. PCP values showed that annual precipitation mainly falls in December and January. Trend analysis demonstrated mostly nonsignificant decreasing trends for all indices, implying a very slight tendency toward a more regular precipitation distribution in a year and a slightly earlier occurrence of precipitation over western Turkey.