OBSERVED CHANGES IN MAXIMUM AND MINIMUM TEMPERATURES IN TURKEY

The aim of this study is to examine the nature and magnitude of the ch anges in mean seasonal daily maximum and minimum temperatures and diur nal temperature ranges for all of Turkey, its regions and the 59 stati ons during the period 1930-1993. Maximum temperatures show significant cooling trends in many stations in summer and autumn. Most of the reg ional mean maximum temperatures have decreased in all seasons, except spring. None of the observed trends in regions was significant statist ically Mean seasonal minimum temperatures have indicated significant w arming trends in many stations in all seasons except winter. Majoritie s of the regional mean minimum temperatures have also increased marked ly in all seasons. Warming trends of spring minimum temperatures were significant over the Black Sea, Aegean and South-eastern Anatolia regi ons. Spring minimum temperatures for all of Turkey have shown a signif icant linear trend, with an increase of +0.145 degrees C per decade. D iurnal temperature ranges have decreased significantly over most of th e regions in all seasons, except partly in autumn and in so many stati ons in all seasons. Most of the decreasing trends in summer were signi ficant at the 1 per cent level. It seems that changes of the diurnal t emperature range in spring, summer and autumn were related closely to changes of maximum temperatures. Thus the decrease of the regional mea n diurnal range was associated mainly with decreases of maximum temper atures in summer and autumn, and with slightly increased maximum tempe ratures in spring. Many stations that experienced a significant trend in diurnal ranges had a significant positive serial correlation. Our f irst results for Ankara have shown no significant trend in the mean mo nthly cloudiness and monthly cloudiness at 1400 hours local time, exce pt a decrease in May cloudiness at 1400 hours.