Observed changes and trends in numbers of summer and tropical days, and the 2010 hot summer in Turkey

Long-term variability and trends of the annual numbers of summer and tropical days were investigated by using nonlinear (monotonic) and linear trend detection tests for the period 1950-2010 for 97 meteorological stations of Turkey. The results suggest that the numbers of both summer and tropical days indicate a general increasing tendency in Turkey. For the study period, statistically significant increasing trends for summer (tropical) days are detected at 64 (71) stations, of which 51 (58) of these positive trends are significant at the 0.01 significance level. Two periods of changes in summer and tropical days are identified: in the 1950-1975 sub-period with an episode of slight cooling, the annual number of summer and tropical days decreases, whereas in the sub-period of 1976-2010 with an episode of significant increasing trend, the annual number of summer and tropical days increases. The summer of 2010 was exceptional for the number of summer and tropical days at most of the stations in Turkey. Normalized anomalies of summer (tropical) days at 2010 were larger than three standard deviations with respect to 1961-1990 normal at 27 (43) stations. The largest positive anomalies are observed in the northeastern Anatolia sub-region. This increasing trend has significant impacts on agriculture, energy, tourism and natural ecosystems (e.g., forest fires) in Turkey. Copyright (c) 2012 Royal Meteorological Society