The El Niño Southern Oscillation (ENSO) dominates the conversation about predictability of climate extremes and early warning and preparedness for floods and droughts, but in Africa other modes of climate variability are also known to influence rainfall anomalies. In this study, we compare the role of ENSO in driving flood hazard over sub-Saharan Africa with modes of climate variability in the Indian and Atlantic Oceans. This is achieved by applying flood frequency approaches to a hydrological reanalysis dataset and streamflow observations for different phases of the ENSO, Indian Ocean Dipole and Tropical South Atlantic climate modes.

Our results highlight that Indian and Atlantic Ocean modes of climate variability are equally as important as ENSO for driving changes in the frequency of impactful floods across Africa. We propose that in many parts of Africa a larger consideration of these unsung climate modes could provide improved seasonal predictions of associated flood hazard and better inform adaptation to the changing climate.

厄尔尼诺南方涛动 (ENSO) 在有关极端气候事件的可预测性以及洪水和干旱的早期预警和准备的讨论中占主导地位，但在非洲，已知其他气候变异模式也会影响降雨异常。在这项研究中，我们比较了 ENSO 在推动撒哈拉以南非洲洪水灾害与印度洋和大西洋气候变化模式中的作用。这是通过将洪水频率方法应用于 ENSO、印度洋偶极子和热带南大西洋气候模式的不同阶段的水文再分析数据集和流量观测来实现的。

我们的研究结果强调，印度和大西洋气候变化模式与 ENSO 一样重要，可以推动整个非洲有影响的洪水频率的变化。我们建议，在非洲的许多地区，更多地考虑这些无名的气候模式可以改进相关洪水灾害的季节性预测，并更好地适应不断变化的气候。