This study identified a relationship between the El Niño-Southern Oscillation (ENSO) and East African drought during the two rainy seasons (i.e., short rain from October to December and long rain from March to May). ENSO shows a positive relationship with the East African short rain during the entire period analyzed (1949–2016). Meanwhile, a statistically significant relationship between ENSO and East African long rain appears only in a recent period (2000–2016), which is unprecedented in the past 50 years before the 2000s. The strengthened interannual relationship between ENSO and East African long rain is associated with distinguished Indian Ocean Walker cell in boreal spring, implying that their relationship could be affected by either multidecadal natural variability or anthropogenic forcing. Various satellite-based drought indices which consider vegetation health, land surface temperature, evapotranspiration, and precipitation with 1 km spatial resolution showed a robust relationship between ENSO and East African drought in the recent period (2000–2016) during the both rainy seasons. In the case studies of June 2005, August 2007, and November 2010, the anomalous wet condition in East Africa during the mature phase of El Nino became dry as La Nina developed in the following year, thereby a lagged response was observed in vegetation-related drought indices and long-term meteorological drought indices. Satellite-based high resolution (1 km) drought indices often showed heterogeneous drought patterns under the same drought condition from reanalysis data at coarse resolution (2.5°), indicating the importance of spatiotemporally continuous high-resolution measurements for drought monitoring in East Africa. Consequently, the synergetic use of high resolution satellite observations and reanalysis data is crucial to provide the effective monitoring, assessment, and seasonal outlook of East African drought.

这项研究确定了两个雨季（即10月至12月的短雨和3月至5月的长雨）期间的厄尔尼诺-南方涛动（ENSO）与东非干旱之间的关系。在整个分析期间（1949-2016年），ENSO与东非短雨呈正相关。同时，ENSO与东非长时间降雨之间的统计上有意义的关系仅出现在最近时期（2000-2016年），这在2000年代之前的过去50年中是前所未有的。ENSO与东非长时间降雨之间加强的年际关系与北方春季杰出的印度洋沃克单元有关，这表明它们的关系可能受到年代际自然变率或人为强迫的影响。考虑到植被健康，地表温度，蒸散和降水的各种基于卫星的干旱指数（空间分辨率为1 km）显示，在两个雨季期间，ENSO和东非干旱在最近一段时间（2000-2016年）之间均存在稳固的关系。在2005年6月，2007年8月和2010年11月的案例研究中，由于第二年的拉尼娜的发展，厄尔尼诺现象成熟期的东非异常潮湿条件变得干燥，因此在与植被有关的反应中观察到滞后的反应。干旱指数和长期气象干旱指数。基于高分辨率（2.5°）的再分析数据，基于卫星的高分辨率（1 km）干旱指数通常在相同干旱条件下显示出异质干旱模式，表明时空连续高分辨率测量对东非干旱监测的重要性。因此，协同使用高分辨率的卫星观测数据和再分析数据对于提供有效的监测，评估和东非干旱的季节性前景至关重要。