Evolution of ENSO-related seasonal precipitation anomalies in East Asia: A robustness revisit

The El Nino-Southern Oscillation (ENSO) is a major source of seasonal climate predictability and a key predictor for East Asian precipitation. However, the impacts of ENSO on East Asian precipitation are extremely complex and still controversial. Thus, it is necessary and significant to use various (observational and model) data sources to further examine the robustness of the impacts. This study revisits the evolution of the ENSO-related seasonal precipitation anomalies in East Asia, including symmetric and asymmetric impacts of El Ninos and La Ninas, the differences in the influences of eastern Pacific (EP) and central Pacific (CP) El Ninos, and the interdecadal change of ENSO influences. The ENSO impact on East Asian precipitation has weakened (strengthened) in the ENSO's developing (decay) phase in the recent two decades. The ENSO impacts are robust in (i) southern China-lower reaches of the Yangtze River-southern Japan around the ENSO's mature phase, (ii) western North China in the developing phase and (iii) southwestern China in the decay phase. The distribution of East Asian precipitation anomalies is asymmetric in El Nino and La Nina years. The model simulations forced with observed sea surface temperature generally reproduce the observed evolution of seasonal precipitation anomalies associated with ENSO and confirm the robust impact of ENSO in East Asia. These results indicate the necessity to consider the asymmetric impact of El Ninos and La Ninas, to distinguish the El Nino flavours for their impact on the East Asian climate, and to include the interdecadal variation of ENSO influence in addressing East Asian climate anomalies.

Automated summary

The El Nino-Southern Oscillation (ENSO) has complex and controversial impacts on East Asian precipitation. In the past two decades, the ENSO impact on precipitation has weakened or strengthened depending on the phase. The distribution of East Asian precipitation anomalies is asymmetric in El Nino and La Nina years. Model simulations confirm the robust impact of ENSO on East Asian climate.