Based on the seasonal mean sea surface temperature(SST) in HadISST,precipitation in CMAP and wind field in the NCEP/NCAR reanalysis dataset,the decaying phase of the 2015/2016 super El Niño event and its associated western North Pacific atmospheric circulation anomaly are investigated in this study.The 2015/2016 El Niño event not only exhibits strong intensity in the mature winter,but also declines rapidly in the subsequent spring and terminates in the summer.During the 2015/2016 winter,the SST anomaly over the central and eastern tropical Pacific is greater than two standard deviations,and is 60% more than the intensity in the composite observations of other El Niño events.This case is recognized as a super El Niño event,but it rapidly declines in the subsequent spring and transforms into a La Niña event in the summer.Additionally,an anticyclonic circulation anomaly persists over the western North Pacific(WNPAC),accompanied by the rapid decline of El Niño.On the one hand,the strong El Niño intensity and its accompanying warming over the Indian Ocean contribute to the steady persistence of the WNPAC associated with the 2015/2016 super El Niño event.On the other hand,the anomalous easterlies over the central and western equatorial Pacific,induced by the strong WNPAC,favor the rapid decline of the El Niño decaying phase.Furthermore,a thorough comparison of the 2015/2016 El Niño event to the cases of 1982/1983 and 1997/1998 suggests that their decaying phases are quite different,despite all being super El Niños with similar wintertime intensity.The 1982/1983 El Niño declines slowly and persists into the following autumn,whereas the 1997/1998 case declines rapidly and has already terminated in the following summer.The length of the El Niño decaying phase is associated with the strength of the springtime WNPAC.The 1982/1983(1997/1998) El Niño is related to a weak(strong) WNPAC in the decaying phase.On the one hand,the decaying rate of the 2015/2016 El Niño is faster than the 1982/1983 case,due to the stronger WNPAC in the 2015/2016 El Niño than that in the 1982/1983 event.On the other hand,the warmest center in the 2015/2016 case is close to the central equatorial Pacific,where the negative SST anomaly first emerges.Thus,although the WNPAC is stronger in 1997/1998 case,the decaying length is similar to the 2015/2016 event.The results imply a complicated interaction between the WNPAC and the El Niño decaying phase,which needs to be further studied.