Contribution of precipitation events with different consecutive days to rainfall change over Asia during ENSO years

Abstract

The present study investigates the contributions of four types of precipitation events with different consecutive days (1–3-day, 4–7-day, 8–14-day, and over-14 day) of precipitation to April–October rainfall anomalies over Asia and roles of the three factors (intensity, number, duration) in area-mean rainfall anomalies of four types of precipitation events in El Nino and La Nina years. It is found that precipitation tends to be below normal in the entire tropical and extratropical regions except for northeastern Asia and east and west Indochina Peninsula during El Nino years. During La Nina years, precipitation tends to increase in eastern China, India, the south hills of the Himalayas, west Indochina Peninsula-southwest China, and the Maritime Continent, but decreases in northeast China, east Kazakhstan, Afghanistan, and east Indochina Peninsula. The precipitation change at the low latitudinal regions has a larger contribution from the over-14-day events. The number of events is a main factor in changes of precipitation of primary events during El Nino years. The precipitation changes in El Nino and La Nina years are consistent with changes in the activity of cyclonic wind anomalies corresponding to the precipitation events. The intraseasonal wind anomalies leading to the precipitation events in China are preceded by northwestward move of cyclonic systems from the tropical western North Pacific that promotes the start of precipitation in the concerned regions. The present study points to the impacts of intraseasonal wind systems with various lifespans on precipitation changes over Asia in El Nino and La Nina years.