Sunshine duration hours over the Greek region

Summary In this study, the temporal and spatial distribution of bright sunshine hours and relative sunshine duration over Greece are presented. The datasets used for this study were obtained from the archives of the Hellenic National Meteorological Service (HNMS). Furthermore, mean annual and seasonal duration of bright sunshine has been estimated from empirical formulae, which depend on the following parameters: (i) percentage of land cover around each station (radius of 20 km), (ii) distance of each station from the nearest coast, (iii) height above sea level for each station location, (iv) latitude of each station, (v) longitude of each station. Differences between measured and estimated bright sunshine hours are accounted for. In general a good relationship exists between estimated and observed sunshine values. The annual march of sunshine is simple with a maximum in July and a minimum in January or December. The spatial distribution of the annual and seasonal bright sunshine duration shows minimum values in the interior mountain areas of the Greek region (Western Macedonia, Epirus, Central Greece), increasing gradually towards the coasts of the Ionian and Aegean seas as well as from north to south. The highest sunshine values occur at the southeastern islands of the Aegean Sea and above the southern coasts of Crete, followed by Attica (Athens area) and the surrounding coastal areas, the islands of the eastern Aegean Sea and the southwestern coastal and island parts of the Ionian Sea.