Cumulative positive contributions of propagating ISO to the quick low-level atmospheric response during El Niño developing years

Based on the Australian Bureau of Meteorology (BoM) El Niño alert system, this study investigates atmospheric and oceanic conditions during developing years between 1982 2016. It is found that there a 2–5-month (subseasonal-to-seasonal) lag to establish steady low-level (or Southern Oscillation Index, SOI) response than Niño-pattern Sea Surface Temperature Anomaly (SSTA), which defined as critical period in research. According duration period, quick slow can be identified among all Niño–Southern (ENSO) events. The establishments Level Pressure (SLPA) tropical atmosphere are proved closely related Intra-seasonal (ISO) In years, ISO events even propagate eastern Pacific, lead cumulative negative Outgoing Longwave Radiation (OLR) SLP anomalies there, make positive contribution at end period. However, eastward-propagation mainly restricted Western Pacific causing with almost no contributions from ISO. Furthermore, observations several simulations used understand propagation differences years.