# Precipitation Products' Inter-Comparison over East and Southern Africa 1983-2017
## 4 Results
### Precipitation Product Intercomparisons at Daily Scale
#### 4.2.2 Quantitative Intercomparisons at Daily Scale  
In Figure 13 the CC, ME, and MAE maps on EA are shown for each pair of intercompared products; the statistical parameters are calculated for each grid cell starting from the daily precipitation time series. The corresponding EA-averaged parameters are reported in Table 5.  
In all three maps, the best CC values between 0.7 and 0.8 characterize the Ethiopian Western Highlands and Northern Tanzania (Figure 13a). In the CHIRPS vs. TAMSAT3 map, the lowest values (CC \(<\) 0.4) are found in the Sudan desert and the region surrounding Lake Victoria. The CHIRPS vs. MSWEP map presents patterns similar to the previous one but with lower average CC values (0.54 with respect to 0.63). In addition to the areas already mentioned with a decrease in CC, the tip of the Horn of Africa in Somalia, Eritrea, Rwanda and Burundi also show a CC \(<\) 0.4. The correlation further deteriorates in the case of the intercomparison of MSWEP vs. TAMSAT3 (CC mean value 0.49), even though the western regions of Ethiopia and South Sudan still exhibit higher CC values. Figure 12: _Cont._  
Systematic differences among the products are identified through the ME maps presented in Figure 13b. A tendency to overestimate daily precipitation characterizes TAMSAT3, more marked with respect to MSWEP, with ME \(>\) 0.4 mm day\({}^{-1}\), than with respect to CHIRPS. In this case, a wide area of EA exhibits values only up to 0.2 mm day\({}^{-1}\), with the exception of Uganda and central Ethiopia (\(\leq\) 0.6 mm day\({}^{-1}\)) and the Kenyan coasts, where on the contrary the underestimation reaches values up to 2 mm day\({}^{-1}\) compared to the average daily precipitation of this region of 3 mm day\({}^{-1}\). Underestimation is most often present in the CHIRPS vs. MSWEP map, with the exception of small regions mainly concentrated in Ethiopia. The spatial distributions of MAE are displayed in Figure 13c. MAE spatial patterns are very similar and underline an increase in MAE associated with the areas characterized by the highest precipitation amounts (i.e., Central-Western Ethiopia, Democratic Republic of Congo and Uganda). Again, the MSWEP vs. TAMSAT3 comparison provides slightly higher values, as reported in Table 5. \begin{table}
\begin{tabular}{c c c c c} \hline  & **POD** & **FAR** & **BIAS** & **HK** \\ \hline CHIRPS vs. TAMSAT3 & 0.71 \(\pm\) 0.15 & 0.29 \(\pm\) 0.13 & 1.0 \(\pm\) 0.18 & 0.65 \(\pm\) 0.14 \\ CHIRPS vs. MSWEP & 0.71 \(\pm\) 0.11 & 0.27 \(\pm\) 0.11 & 0.98 \(\pm\) 0.13 & 0.64 \(\pm\) 0.11 \\ MSWEP vs. TAMSAT3 & 0.67 \(\pm\) 0.16 & 0.34 \(\pm\) 0.13 & 1.03 \(\pm\) 0.19 & 0.59 \(\pm\) 0.15 \\ \hline \end{tabular}
\end{table} 
Table 4: Same as in Table 3 but for SA. Figure 12: Maps of POD (**a**), FAR (**b**), BIAS (**c**) and HK (**d**) for SA. Figure 13: Maps of CC (**a**), ME (mm day\({}^{-1}\)) (**b**) and MAE (mm day\({}^{-1}\)) (**c**) for EA. \begin{table}
\begin{tabular}{c c c c} \hline \hline  & **CC** & \
\begin{tabular}{c} **ME** \\ **[mm day\({}^{-1}\)]** \\ \end{tabular} &
\begin{tabular}{c} **MAE** \\ **[mm day\({}^{-1}\)]** \\ \end{tabular} \\ \hline CHIRPS vs. & \(0.63\pm 0.08\) & \(0.06\pm 0.20\) & \(1.48\pm 1.00\) \\ CHIRPS vs. MSWEP & \(0.54\pm 0.13\) & \(-0.16\pm 0.30\) & \(1.49\pm 0.99\) \\ MSWEP vs. & \(0.49\pm 0.13\) & \(0.23\pm 0.33\) & \(1.66\pm 1.08\) \\ \hline \hline \end{tabular}
\end{table} 
Table 5: CC, ME and MAE spatially averaged over EA with corresponding standard deviations. These results are closely linked with the dichotomous statistics outcomes and also support the results from the analysis of the monthly climatology for the clusters. Even though the three products have a high degree of agreement, generally TAMSAT3 and CHIRPS are the products with more similar behavior at the daily scale in EA in terms of precipitation detection and quantification, whereas the MSWEP results are worse, especially with respect to TAMSAT3, in both aspects.