# Precipitation Products' Inter-Comparison over East and Southern Africa 1983-2017
## 4 Results
### Cluster Analysis and Precipitation Seasonality
Cluster 5 is characterized by a reduced but still significant amount of precipitation during the austral winter months from May to September, and is mainly located on the east coast of Madagascar, which receives precipitation throughout the year (Figure 4). This cluster also includes the coast of Mozambique and western region of RSA. Cluster 4 occupies the Namib Desert and is therefore characterized by very low rainfall throughout the year, with a precipitating period limited to January, February and March. Finally, cluster 6, covering the coastal region of Cape Town and eastern RSA is the only one with a precipitation annual cycle very different from the rest of SA; precipitation is generally very scarce, with a weak increase from April to September. The average annual precipitation cycles for each satellite dataset and cluster are shown in Figure 9. The shaded areas represent the corresponding standard deviation values, as in Figure 6. The correlation among the annual cycles belonging to the same cluster has also been explored in this case, with analogous results for the EA cluster analysis. The satellite products responded positively to SA territory clustering, reproducing the annual cycles from GPCC_Clim data in terms of seasonality and precipitation amount. A substantial agreement among the annual cycles of the three precipitation products is evident from Figure 9, except for cluster 5 and 6 characterized by the TAMSAT3 underestimation, particularly marked from January to September in cluster 5 and from April to June in cluster 6. Generally speaking, the variability of the precipitation products' annual cycles  
Figure 6: Mean precipitation annual cycles for each EA cluster, from cluster 1 (**a**) to cluster 8 (**h**), and precipitation product: MSWEP (green), CHIRPS (red), and TAMSAT3 (blue). The shaded areas identify the standard deviation (\(\pm\sigma\)) for each precipitation product, MSWEP (light green), CHIRPS (pink) and TAMSAT3 (light blue). within the clusters is very similar (i.e., \(\sigma\) values are comparable among the products in each cluster, with the exception of cluster 5 in May-September). The significantly high variability seen, for instance, during the austral summer months in cluster 1 and 5 is mainly due to the composite nature of the cluster affecting the precipitation amount even though the seasonality is preserved. As an example, Figure S1 shows the case of cluster 5, with mean annual cycles over the eastern coast of Madagascar (Figure S1a), the coast of Mozambique (Figure S1b), and central RSA (Figure S1b). Figure 7: EA cluster–average monthly ME and MAE values from TAMSAT3 with respect to CHIRPS (**a,b**), MSWEP with respect to CHIRPS (**c,d**), and TAMSAT3 with respect to MSWEP (**e,f**). The agreement among the SA annual cycles for each cluster and the three products has been evaluated through the ME and MAE as previously done for EA (Figure 10). In terms of ME, the highest values (negative) are related to clusters 5 and 6 from April to September, due to TAMSAT3 underestimation of the low intensity precipitation with respect to CHIRPS and MSWEP (Figure 10a,e). The same is not true for the other clusters, where TAMSAT3 exhibits much more limited ME values; thus, this effect does not seem particularly connected to a specific inadequacy of TAMSAT3 for light precipitation estimation, as it is also confirmed by the corresponding MAE values (Figure 10b,d,f). Conversely, substantial agreement is evident between CHIRPS and MSWEP for the same period (Figure 10c,d) and clusters. Considering the precipitating months (ONDjFM, excluding cluster 6), the best ME and MAE values emerge from the TAMSAT3 versus CHIRPS comparison (Figure 10a,b), whereas MSWEP overestimates monthly precipitation with respect to both TAMSAT3 and CHIRPS. Figure 8: Same as in Figure 5, but for SA. Figure 9: Same as in Figure 6 but for SA, from cluster 1 (**a**) to cluster 6 (**f**).