## 4 Energy Balance
In fact, the SITE model struggles to represent the variability of latent heat (LE) and sensible heat (H) throughout the day, likely due to the model's failure to account for daily changes in certain \begin{table}
\begin{tabular}{l c c c c c c} \hline \hline  & \multicolumn{3}{c}{**2009 (Heavy Rainfall)**} & \multicolumn{3}{c}{**2012 (Extreme Drought)**} \\ \cline{2-7}  & **Annual** & **Wet Season** & **Dry Season** & **Annual** & **Wet Season** & **Dry Season** \\ \hline Rn (Wm\({}^{-2}\)) & 166.4 & 170.2 & 166.7 & 163.4 & 167.4 & 164.4 \\ LE (Wm\({}^{-2}\)) & 42.6 & 59.0 & 35.9 & 32.8 & 43.5 & 26.0 \\ H (Wm\({}^{-2}\)) & 60.6 & 41.8 & 88.8 & 80.4 & 53.8 & 115.6 \\ G (Wm\({}^{-2}\)) & 0.9 & 0.8 & 0.7 & 0.7 & 0.3 & 0.6 \\ R (Wm\({}^{-2}\)) & 62.3 & 68.6 & 41.3 & 49.5 & 69.8 & 22.2 \\ ED (Wm\({}^{-2}\)) & 165.6 & 169.4 & 166.0 & 162.7 & 167.1 & 163.8 \\ EBC & 0.62 & 0.60 & 0.75 & 0.70 & 0.58 & 0.86 \\ LE/Rn (\%) & 25.6 & 34.0 & 21.5 & 20.0 & 26.0 & 16.0 \\ H/Rn (\%) & 36.4 & 24.5 & 53.3 & 49.2 & 32.1 & 70.3 \\ G/Rn (\%) & 0.5 & 0.48 & 0.4 & 0.4 & 0.2 & 0.3 \\ R/Rn (\%) & 40 & 20 & 40 & 30 & 20 & 40 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Annual averages of Rn, LE, H, and G, in addition to the closure residual (R) and partitioning of the energy balance. environmental parameters such as soil moisture fraction and diurnal variations in the stomatal opening and closure of plants. In relation to LE and H, Table 2 shows a condition of nearly constant water deficiency in the region, as H consistently surpasses LE, even during the comparatively wetter year of 2009. This behavior of LE and H in the Caatinga has been previously investigated and discussed in the scientific literature [10; 19; 22]. Table 2 also clearly shows the influence of rainfall on the seasonality of the energy balance components and their partitions. During the wet season, the portion of Rn converted to LE is nearly 60% higher compared to the dry season. On the other hand, the portion of Rn converted to H during the dry season is almost twofold higher than in the wet season. The role of rainfall is also illustrated in the interannual relationship. In 2009, a year characterized by higher rainfall, H was almost 50% higher than LE on an annual basis. Similarly, in 2012, H exceeded LE with a difference of more than 100%. The portion of Rn converted to LE was more than 25% in 2009 and 20% in 2012. In contrast, the portion of Rn converted to H was slightly above 35% in 2009 while it reached nearly 50% in 2012. These seasonal and interannual variations in the values of the energy balance components and their respective partitions have also been widely reported in the literature within tropical and/or semiarid environments [10; 22; 39]. In relation to G, results indicate that the mean annual value was higher in 2009 compared to the value simulated in 2012. This difference is likely attributed to more intense rainfall, which interfered with the temperature differences between the atmosphere and the soil, as well as runoff. These factors are important parameters for quantifying G in the model, as they represent energy loss from the soil to the atmosphere. Despite these differences, their absolute values did not affect the difference between available energy (Rn-G) for both years, since the difference was similar to those observed in the Rn values. This implies that, in terms of energy availability, both years were practically equal. The absence of rainfall during the dry season in the Caatinga can lead to changes in the energy balance, causing an increase in H fluxes and a decrease in LE fluxes. These changes modify the turbulent exchanges of heat and moisture that occur between the surface and the atmosphere [54; 55; 56]. When comparing LE between seasons, it was observed that the averages with greater amplitudes occurred during the wet season, reaching almost 60 Wm\({}^{-2}\). In contrast, during the dry season, these values remained below 40 Wm\({}^{-2}\) throughout the year 2009.