# Monthly Precipitation over Northern Middle Atlas, Eastern Morocco: Homogenization and Trends
## 4 Discussion  
The test of the impact of homogenization on the quality of the data used in this study was carried out through the comparison between the results from the raw data and those from the homogenized series. The correlograms of the correlation coefficients show a remarkable change towards more physically plausible correlation patterns related to the correction and the reconstruction of the data. On average, the difference between the originally-recorded and homogenized precipitation is 8.5 mm. This result is consistent with the results of the work of [PERSON] et al. (2016) carried out in the Fez-Meknes region (very close to our study area), where the average found is 6 mm. The work of [PERSON] et al. (2010), carried out on the Sous Massa basin, displays an RMSE between 11.7 and 23.4. This shows that our data was not strongly affected by homogenization. The importance of homogenization is observed more in the shortest series, which contain many gaps, particularly in the mountainous part where the density of the network of stations is sparse. On the other hand, this operation has less importance in the correction of the data in our field (given the microclimatic particularities of each group of stations), which required accepting sometimes-large differences in precipitation over small distances. The same result was reported by [PERSON] et al. (2018) and by [PERSON] et al. (2016). The power and robustness of the Climatod tool also appear in the regionalization of statistical series using clusters, which groups together stations with similar rainfall variability and precipitation patterns. This technique allowed us to find two different climatic zones. The first one has a winter regime, is located in the west of the mountain range of Jbel Bouiblane, and is exposed to disturbances from the north and west. The second, considered arid to semi-arid, has a spring regime and is located east of Jbel Bouiblane. Our results on regionalization are consistent with those of [PERSON] et al. (2016), and close to those of [PERSON] et al. (2015) who carried out a regionalization of rainfall throughout the country. Despite the low number of stations used in his work compared to the study area size, [PERSON] (2015) presented similar results on the regionalization of precipitation in Atlantic Morocco, particularly with regard to the western part of Jbel Bouiblane. The analysis of the monthly rainfall trends of the homogenized data was carried out using the Mann-Kendall test at the alpha thresholds 0.01, 0.05 and 0.1%. The main results show a widespread significant increase in precipitation from August to November. In their work carried out on the Melloulou wadi basin, [PERSON] et al. (2016) showed an increase of  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline \multicolumn{1}{c}{\multirow{2}{*}{_ID_}} & \multirow{2}{*}{**[PERSON]**} & \multirow{2}{*}{**[PERSON]**} & \multirow{2}{*}{**[PERSON]**} & \multirow{2}{*}{**[PERSON]**} & \multirow{2}{*}{**[PERSON]**} & \multirow{2}{*}{**[PERSON]**} & \multirow{2}{*}{**[PERSON]**} & \multirow{2}{*}{**[PERSON]**} & \multirow{2}{*}{**[PERSON]**} & \multirow{2}{*}{**[PERSON]**} \\  & & & & & & & & & & & & & & \\ \hline S1 & \(-\)0.23 & \(-\)1.05 & \(-\)0.92 & \(-\)0.64 & \(-\)0.38 & \(-\)0.64 & 1.12 & **2.86*** & 3.35** & 2.52** & 2.53  
annual rainfall between 2000 and 2014, directly linked to a significant trend in autumnal rainfall. In addition, the results of a study carried out on the northwestern part of Algeria by [PERSON] [55] addressed positive annual rainfall trends. This author explained this increase as the result of the increase in the number days of extreme rainfall events (which generally occur in summer and autumn). Also, [PERSON] et al. [56] found similar results in southern Morocco. At the level of the northeastern part of Tunisia, [PERSON] et al. [57] reported that there had been a return of precipitation since the beginning of the 2000s. These last authors did not determine the month or months of the year that accounted for this increase.