1. a University of Athens , Department of Applied Physics , Building PHYS-V, Athens, GR-15784 Greece
2. b Foundation for Research and Technology—Hellas, Institute of Applied and Computational Mathematics , Regional Analysis Division , P.O. Box 1527, Heraklion, Crete, GR-71110 Greece E-mail:
3. c University of the Aegean, Department of Geography , University Hill , Building of Geography, GR-81100 Mytilene, Greece
4. d National Meteorological Service , Hellinikon, Athens, Greece