The impact of the Madden-Julian Oscillation on hydrological extremes

Abstract Extreme climate events such as severe droughts and floods have become more frequent and widespread in the 21st Century. Recent studies have revealed the tele-connections between Madden–Julian Oscillation (MJO) and extreme precipitation over different regions such as South America, India and China. This study investigates the influence of MJO on global extreme dry and wet conditions, and how the strength of the relationship changes across the MJO phases over the globe. The Evaporative Stress Index (ESI) calculated from global GLEAM evapotranspiration dataset is used to represent extreme dry and wet conditions. Strong correlations between MJO and extreme dry and wet conditions are found, particularly over monsoon regions such as South Asia, South America and East Africa. The underlying mechanism of the influence of MJO on extreme dry and wet conditions is associated with the variation of precipitation, air temperature and soil moisture modulated by the MJO. The study suggests that MJO impacts on extreme dry and wet conditions should be taken into account in investigation of droughts/floods around the world particularly over monsoon areas.