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Impacts of ENSO and ENSO Modoki+A regimes on seasonal precipitation variations and possible underlying causes in the Huai River basin, China

Zhang, Qiang, Wang, Yue, Singh, Vijay P., Gu, Xihui, Kong, Dongdong, Xiao, Mingzhong
Journal of hydrology 2016 v.533 pp. 308-319
El Nino, atmospheric precipitation, autumn, basins, climate change, cold, cooling, drought, floods, risk, seasonal variation, spring, summer, water vapor, watersheds, China
Spatiotemporal patterns of seasonal precipitation changes across the Huai River basin, China, were analyzed, using daily precipitation data from 35 meteorological stations for the period of 1961–2010. Seasonal precipitation changes in related to Eastern Pacific Warming (EPW), Central Pacific Warming (CPW), and Eastern Pacific Cooling (EPC) were investigated. Impacts of canonical ENSO (c-ENSO) and ENSO Modoki+A (EM+A) on seasonal precipitation variations were evaluated. Water vapor transport patterns were also examined to determine the possible mechanisms causing the impacts of ENSO regimes on seasonal precipitation changes. Results indicated that: (1) EPC is the main driver for the increase of spring and autumn precipitation and autumn/spring precipitation tends to decrease during CPW/EPW, respectively. However, EPW and CPW can result in an increase of the summer precipitation amount in the middle and upper basin, and EPC causes an increase of the spring precipitation amount, which may amplify flood risk in the basin; (2) c-ENSO regimes tend to increase the precipitation amount during spring and autumn, especially for the winter precipitation amount. However, c-ENSO and EM+A cause distinctly different impacts on the summer and autumn precipitation: a decrease of summer and autumn precipitation is observed during the EM+A periods while an increase during the c-ENSO periods; (3) In summer and spring, water vapor transport during the c-ENSO periods is more active than during the EM+A periods. Further, water vapor flux is more abundant during the warm episodes of c-ENSO events in spring and summer than during the cold episodes of c-ENSO, and hence higher spring and summer precipitation across the basin. Results of this study may help to understand the causes underlying spatiotemporal patterns of seasonal precipitation and can help in developing measures for the mitigation of floods and droughts hazards in a changing climate.