Determination of places in the great Athens area where the heat island effect is observed

Summary The major Athens area is surrounded by high mountains to the north and the east and is influenced by the sea (Saronic Gulf) to the south. As a result of its topography, the city experiences significant variations in its ventilation patterns even over small distances. The main purpose of the present study is to define places in the major Athens area where the heat island effect occurs. Several important climatic parameters are examined in combination with the application of various statistical tests. From this research it is mainly observed that the central and western industrialized parts of the city of Athens develop the “urban” heat island effect intensely. Nevertheless, district variations as regards the heat island intensity can be found in some regions, located close to the city centre and eastward of it, characterized by thick vegetation of trees or by “open areas”. Moreover, in places near the sea the air temperatures are higher in the cold period of the year, not because of the urbanization but mainly due to the influence of the sea, which favors the maintenance of high air temperatures. Last but not least, the persistence of high air temperatures during the hot period of the year or low air temperatures in the cold period is mostly related to the synoptic weather conditions and it cannot reasonably be considered as an index for the heat island effect development. Received June 1, 2000 Revised August 6, 2001