4.2 Climate severity

Rainfall severity indices are derived by considering all observations which are less than 25% (first quartile) of the ranked historical records to be dry while those which are more than 75% (third quartile) are considered wet.

Figure 2 shows the spatial pattern of the rainfall severity index for the GHA sub-region during July 2008. Near normal to wet conditions were recorded over the western and central parts of the northern sector as well as the extreme western parts of the equatorial sector. Much of the southern and equatorial sectors experienced generally dry conditions.

Figure 2: Rainfall severity index for July 2008 (Indice de rigueur de la sécheresse pour le mois de juillet 2008)

4.2.1 Cumulative climate stress severity monitoring

The extent of climate-related impact on any particular system depends on the severity and duration of the climate stress. The cumulative climate stress severity has direct and indirect severe impacts on livestock, food security, water resources, health and many other socio-economic sectors. The cumulative rainfall performance for some selected stations in the GHA sub-region for the January to July 2008 period is shown by Figures 3a and 3b. Wet conditions were observed over the western and central parts of the northern sector (figure 3a) while below normal conditions were experienced over parts of the equatorial sector (figure 3b) during this period.

Figure 3a: Cumulative rainfall series for selected stations (séries de pluviométrie cumulée pour des stations sélectionnées)

Figure 3b: Cumulative rainfall series for selected stations (séries de pluviométrie cumulée pour des stations sélectionnées