SDS-WAS No. 2015-001
Dust/ sand storms over Libya
Spatial distribution, frequency and seasonality, technical report
The climate of most of the coastal region of Libya can be classified as semi-arid, while that of the rest of the country is arid. Rainfall is erratic with extremely variable yearly rainfall amounts: a series of dry years may follow a year with adequate rainfall. Furthermore, monthly and seasonal totals are not homogenous and most precipitation occurs during winter months. Dust and sand storms, the focus of the present study, are one of the main extreme weather phenomena that affect Libya. In this paper, spatial and temporal distribution, frequency and seasonality are studied and analyzed. Normal frequency for the period 1961-1990 is computed and discussed on seasonal and annual basis. Finally, the annual frequency for the period 2000-2009 is computed and compared with the normal values in order to analyze temporal trends. The analysis concludes that sand and dust storms occur in most stations almost the whole year. They are more frequent in spring, especially in April, with the highest annual frequencies observed at Tobruk airport (14.9 days), Hon (12.9), Sirt (11.2( and Ghadames (11.1). A net decrease of 30% is observed during the decade 2000-2009 when compared with the normal values for 1961-1990.