Intraseasonal Variability of East Asian Monsoon Precipitation

The East Asian monsoon system exhibits pronounced fluctuations on timescales of two to eight weeks. These intraseasonal variations govern the alternation of active and break periods in rainfall, shaping the onset, intensity and duration of summer rains across eastern China, the Korean Peninsula and parts of Japan. Central to this variability are large‐scale coupled dynamics, including interactions between the subtropical westerly jet, tropical convective disturbances and mid‐latitude wave trains. Oscillations such as the Madden–Julian Oscillation modulate moisture convergence and vertical motion, while quasi-biweekly cycles linked to the Tibetan Plateau heat source influence the timing and propagation of rain bands downstream. The interplay of high-frequency (8–20 days) and low-frequency (20–70 days) modes determines the predictability of subseasonal rainfall, with high-frequency signals often dominating week-two and week-three forecasts. Intraseasonal variability has practical consequences for flood risk management, crop planning and water resource allocation, and underpins emerging subseasonal-to-seasonal prediction systems. Enhanced understanding of these mechanisms is essential not only for improving forecast skill over East Asia but also for clarifying teleconnections with the wider Asian-Australian monsoon and extratropical circulation anomalies under a warming climate.

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Intraseasonal Variability of East Asian Monsoon Precipitation publication trend

The graph below shows the total number of articles in intraseasonal variability of east asian monsoon precipitation across all publications each year (not limited to Nature Index journals).

Technical terms

Intraseasonal variability (ISV): Fluctuations in atmospheric and oceanic fields on timescales of roughly 10–90 days.

Madden–Julian Oscillation (MJO): A planetary-scale eastward-propagating convective pattern with a 30–60 day period that influences monsoon activity.

Quasi-biweekly oscillation (QBW): A 12–20 day cycle of alternating wet and dry phases linked to regional heating and circulation anomalies.

Subtropical westerly jet (SJ): A high-altitude, fast-flowing air current whose position and strength affect downstream moisture transport.

Convectively coupled equatorial waves: Tropical wave disturbances that interact with convection, modulating rainfall patterns on intraseasonal timescales.

References

1. Intraseasonal variability of global land monsoon precipitation and its recent trend. npj Climate and Atmospheric Science (2022).
2. Quasi-biweekly impact of the atmospheric heat source over the Tibetan Plateau on summer rainfall in Eastern China. Climate Dynamics (2019).
3. Intraseasonal variability of summer monsoon rainfall over the lower reaches of the Yangtze River basin. Atmospheric and Oceanic Science Letters (2020).