CR 28:229-241 (2005)  -  doi:10.3354/cr028229

ABSTRACT: In the present study, hot spell conditions over the Greek region during the warm period (June to September) were examined by using daily maximum temperature data from 16 meteorological stations of the Hellenic National Meteorological Service (HNMS) and a combined deterministic-stochastic model. The results show that daily maximum temperatures can be studied as a mixture of deterministic and stochastic components, whereas the properties of hot spells can be adequately described with statistical distributions. Trends and the geographical and temporal distribution of hot spells at the surface were investigated by linear regression, Fourier analysis and statistical distributions. Partial duration series of hot spells, fitted with Poisson, Gauss and exponential distributions, provide information on their frequency, timing, magnitude and geographical distribution. The most frequent hot spells are found over southern parts of inland Greece, as well as over the northern mainland, while less frequent events occur along the coastal belt of the Greek Peninsula and in the Aegean islands. Hot spells are more frequent at inland than in marine areas, and occur from June to September. Statistical analysis of synoptic weather conditions that favour the development of hot spells shows that such events are most probable over Greece when (1) a persistent Azores anticyclone appears over North Africa and extends ridges of high pressure towards the NE Mediterranean, and (2) when western and central European anticyclones extend towards the region.

KEY WORDS: synoptic weather conditions · hot spell · frequency · timing · magnitude · statistical distributions