Linke turbidity factors for several sites in Africa

The Linke turbidity factor (TL) has been estimated at 16 locations in Africa (9 stations in Egypt, 2 in Mozambique and Zimbabwe, I in Algeria, Tunisia and Zambia). An appropriate processing of time-series of measurements of daily sums of solar global radiation spanning several years provides mean values of TL for each month with a sufficient accuracy. Though limited to the Mediterranean area, Egypt and sub-tropical Southeastern part, this work greatly extends the knowledge on the clearness of the atmosphere in Africa, an area not much addressed in the literature. The relationship between TL and the climate is evidenced. TL is almost constant throughout the year close to the Mediterranean basin with values around 3.5. Stations located in the sub-tropical Southeastern part exhibit large variations of TL. (C) 2003 Elsevier Ltd. All rights reserved.