This paper investigates the features of extreme rainfalls and associated floods during March to May (MAM) season in 2016 over Rwanda and the atmospheric circulation influencing these rainfalls. All stations over the study area received above the average rainfall during MAM (long rain) season in 2016. Among all the months in this season, the rainiest month was April when most parts of the country received highest amounts of rainfall (≥ 180 mm). The presence of anomalous high pressure over the southwestern Indian Ocean, with the help of intense Mascarene high, advected warm moist air through southeasterly winds toward the study area. During this rainy season, the study area was characterized by convergence (divergence) in the lower (upper) troposphere, implying ascending (descending) motion. The ascending moist air at lower level enhanced convection and hence enhanced rainfall over Rwanda. This is associated with more convective activities over central Indian Ocean, and central to eastern Pacific Ocean due to vertical stretching. Moreover, the heavy rainfall events occurred in 2016 are strongly connected to Indian Ocean Dipole Modoki and El Niño due to observed above normal Sea Surface Temperature anomalies over the central Indian Ocean and central to eastern Pacific Ocean, respectively.

本文研究了卢旺达2016年3月至5月（MAM）季节的极端降雨和相关洪水的特征以及影响这些降雨的大气环流。研究区域内的所有气象站在2016年的MAM（长时间降雨）季节均收到高于平均降雨量的降雨。在该季节的所有月份中，最雨的月份是4月，该国大部分地区降雨量最高（≥180 mm） 。在印度洋西南部异常高压的存在下，借助强烈的玛斯卡林高，平流湿热空气，通过东南风吹向研究区域。在这个雨季，研究区的特征是对流层下部（上部）会聚（发散），这意味着上升（下降）运动。较低水平的上升湿空气增强了对流，因此增加了卢旺达的降雨。这与印度洋中部以及由于垂直伸展而对太平洋中部至东部的更多对流活动有关。此外，由于分别在印度洋中部和太平洋中部至东部海域观测到高于正常海面温度的异常现象，2016年发生的强降雨事件与印度洋的偶极子Modoki和厄尔尼诺现象密切相关。