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Figures 4.2 and 4.3 show, respectively, the spatial distribution and biases of the surface temperature for the reanalysis data (ERA 5 and ERA‐Interim) and the two experiments carried out with the RegCM model over the period from 2001 to 2006. Reanalysis data (Figure 4.2 a–h) show that the spatial distribution of temperature is strongly influenced by relief (Kamga, 2001). Thus, the highest temperatures (> 32 °C) are located in the northern part of the domain while the lowest temperatures (< 18 °C) are observed along the coasts of the Atlantic and Indian Oceans, and also around mountainous regions. Biases of about 3 °C are reported between the two reanalysis products at high relief areas and land‐ocean boundaries (Figure 4.3 a–d), highlighting the presence of uncertainties between the two data sets. In comparison with the reanalysis data, RegCM’s simulations satisfactorily locate the zones of temperature maxima and minima both on the continent and in the oceans. However, as the panels in Figure 4.3 e–l show, the maxima (minima) are overestimated (underestimated) by the model in both experiments. Nevertheless, we note that experiments with slab‐ocean present more extensive biases over the Atlantic Ocean, but these are less extended over the continent and almost zero over the Indian Ocean. The reduction or cancellation of the range of biases noted above can be attributed to the presence of the slab‐ocean, which interacts with the atmosphere, forcing it to calculate realistic SST. We also note that the experience with slab‐ocean has great added value compared to that without slab‐ocean.

Figure 4.2 Seasonal means of the surface air temperature (T2m °C) for the period 2001–2006: ERA 5 (a–d), ERA‐Interim (e–g), GFC_SLAB (i–l), GFC_CTR (m–p).

Figure 4.3 Bias of mean seasonal surface air temperature (T2m °C) for the period 2001–2006: ERA‐Interim ‐ ERA 5 (a–d), GFC_SLAB ‐ ERA5 (e–g), GFC_CTR ‐ ERA 5 (i–l), GFC_SLAB ‐ GFC_CTR (m–p).