The Sahara is the largest and driest of the hot deserts on Earth, with regions where rainfall reaches the surface on average less than once a year. Water resources are scarce, and rainfall tends to occur sporadically in space and time. While rain is a precious resource in the Sahara, heavy precipitation events (HPEs) in the desert have the potential to trigger flash floods on the barren soil. Because of the sparse rainfall monitoring network and the relatively poor performance of global models in representing rainfall over the Sahara, the analysis of Saharan HPEs has primarily relied on case studies. Therefore, general rainfall characteristics of Saharan HPEs are unexplored, and the prevailing weather conditions enabling such rainfall are unknown. To tackle this problem, we utilised satellite-derived precipitation estimations (IMERG) spanning 21 years (2000–2021) to identify $\sim 42\cdot 10^3$ small ($>10^3{\mathrm{km}}^2$) to large ($<10^6{\mathrm{km}}^2$) HPEs in the Sahara and to extract their rainfall properties, and atmospheric reanalyses (ERA5) to examine the corresponding meteorological conditions in which they develop. Three case studies illustrate the relevance of cyclones for exceptionally large HPEs, including one in the driest region of the Sahara. Saharan HPEs occur, on average, every second day. They are more common in summer than in the other seasons, occur most frequently in the southern Sahara, and exhibit a clear convectively-driven diurnal cycle. Winter events have, on average, larger spatial extent, longer duration, and are characterised by larger areas exhibiting more extreme rainfall in terms of return periods. Autumn HPEs are concentrated in the western Sahara, while events in the north of the desert and in its driest core in the northeast occur mainly in winter and spring. In these regions, north of the Tropic of Cancer, events are highly associated with surface cyclones. HPEs that were associated with cyclones are characterised by larger spatial extent and rainfall volume. Considering that weather and climate models often depict synoptic-scale weather systems more accurately than rainfall patterns, the association of Saharan HPEs with surface cyclones and other synoptic-scale systems can aid in comprehending the effects of climate change in the desert. Furthermore, it underscores the potential for higher predictability of these events.

撒哈拉沙漠是地球上最大、最干燥的炎热沙漠，该地区的降雨量平均每年不到一次。水资源稀缺，降雨在空间和时间上往往是零星的。虽然雨水是撒哈拉沙漠的宝贵资源，但沙漠中的强降水事件 (HPE) 有可能在贫瘠的土壤上引发山洪。由于降雨监测网络稀疏，且全球模型在表征撒哈拉降雨量方面表现较差，因此对撒哈拉HPE的分析主要依赖于案例研究。因此，撒哈拉 HPE 的一般降雨特征尚未被探索，并且导致这种降雨的主要天气条件也是未知的。为了解决这个问题，我们利用跨越 21 年（2000 年至 2021 年）的卫星降水估算 (IMERG) 来确定$～42\cdot 10^3$小的 （$>10^3{\mathrm{公里}}^2$) 到大 ($<10^6{\mathrm{公里}}^2$）撒哈拉沙漠中的 HPE 并提取其降雨特性，并进行大气再分析（ERA5）以检查它们形成的相应气象条件。三个案例研究说明了气旋与特大型高能物理场的相关性，其中包括撒哈拉最干旱地区的一个。撒哈拉 HPE 平均每两天发生一次。它们在夏季比其他季节更常见，最常发生在撒哈拉南部，并表现出明显的对流驱动的昼夜循环。平均而言，冬季事件的空间范围更大、持续时间更长，其特点是重现期出现更极端降雨的地区更大。秋季HPE集中在西撒哈拉，而沙漠北部和东北部最干燥的核心地区的事件主要发生在冬季和春季。在北回归线以北的这些地区，事件与地面气旋高度相关。与气旋相关的 HPE 的特点是空间范围更大、降雨量更大。考虑到天气和气候模型通常比降雨模式更准确地描述天气尺度的天气系统，撒哈拉 HPE 与地面气旋和其他天气尺度系统的关联可以帮助理解沙漠气候变化的影响。此外，它强调了这些事件具有更高可预测性的潜力。