A statistical study of precipitation in northwest Greece

✍ Scribed by Fotiadi, A.K.; Metaxas, D.A.; Bartzokas, A.

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 195 KB
• Volume: 19
• Category: Article
• ISSN: 0899-8418
• DOI: 10.1002/(sici)1097-0088(199909)19:11<1221::aid-joc436>3.0.co;2-h

✦ Synopsis

In this paper, using 20 year mean monthly precipitation totals from 54 stations, the general statistics for the time and space distribution of precipitation in northwest Greece is at first described. Precipitation varies from about 1000 mm at the coast to 2500 mm on the mountains, with a large variability. Then, the intra-annual variation is studied, using Fourier analysis. This variation is described well by two harmonics, explaining about 90% of the total variance. The first harmonic, over 80% of the variance, shows a maximum from late December (coastal areas) to early January (continental areas) and is caused by the northwest Mediterranean depression activity. The second harmonic exhibits maxima in May and November, also delayed in the continental areas, and is mainly caused by upper air troughs and instability. The spatial distribution of precipitation is then studied by using factor analysis. The 12 months of a year are classified in two parts corresponding to two statistically significant factors, explaining 88.5% of the total variance. Finally, the combination of positive and negative standardized scores of the two factors showed that northwest Greece is characterized by four precipitation regimes, depending on the combination of depression activity, the effects of the sea and of topography.