The West African Sahel: A Review of Recent Studies on the Rainfall Regime and Its Interannual Variability
Figure 17
(a) Speed of the westerlies (m s−1) at 850 hPa versus surface pressure gradient for August of the years 1948–2004 (from [95]). Data are averaged for 5° W to 5° E and the pressure gradient is calculated between 20° N and 20° S. The open circles represent the years 1948–1969 and the solid circles represent the years 1970–2004. (b) Annual rainfall in the Sahel (averaged within the sector 10–18° N and from the Atlantic coast to 30° E) versus speed of the westerlies at 850 hPa (from [20]).
