Analysis of Changes in Sunshine Duration Data for Ankara, Turkey

Summary  The variations and trends of hourly sunshine duration at Ankara for the period 1955–1996 were examined. A tangible change of 7 percent was determined relative to the annual baseline. Decreases were detected in each hour of the day and appear to be highest at sunrise and sunset. Changes in relative humidity that may lead to changes in the threshold of the sunshine recorders were evaluated in order to explain the decreases of sunshine duration. Correlations with other meteorological parameters were also analysed. The results indicate that the variations and trends in sunshine duration can be explained by changes in the other meteorological parameters. Received September 11, 1998 Revised March 18, 1999