TheElNino-SouthernOscillation(ENSO)reflectsanomalousvariationsintheseasurfacetemperature(SST)andatmosphericcirculationoverthetropicalcentral-easternPacific.Itremarkablyimpactsonweatherandclimateworldwide,somonitoringandpredictionofENSOdrawintensiveresearch.However,thereisnotyetauniquestandardinternationallyforidentifyingthetiming,intensity,andtypeofENSOevents.TheNationalClimateCenterofChinaMeteorologicalAdministration(NCC/CMA)hasledtheefforttoestablishanationalidentificationstandardofENSOevents,whichwasofficiallyendorsedbytheNationalStandardizationAdministrationofChinaandimplementedoperationallyinNCC/CMAin2017.Inthispaper,twokeyaspectsofthisstandardareintroduced.First,theNino3.4SSTanomalyindex,whichiswell-recognizedintheinternationalENSOresearchcommunityandusedoperationallyintheUS,hasreplacedthepreviousNinoZindexandbeenusedtoidentifythestart,end,andpeaktimes,andintensityofENSOevents.Second,twonewindices-theeasternPacificENSO(EP)indexandthecentralPacificENSO(CP)index,basedontheSSTconditionsinNino3andNino4regionrespectively,arecalculatedtofirstdeterminetheENSOtypebeforemonitoringandassessingtheimpactsofENSOonChina’sclimate.Withthisstandard,allhistoricalENSOeventssince1950areconsistentlyre-identified;theirdistinctpropertiesarediagnosedandpresented;andtheimpactsofENSOeventsunderdifferenttypesonChina’sclimatearere-assessed.Thisstandardisalsoemployedtovalidatetheintensity,grade,andtypeoftheENSOeventspredictedbytheNCC/CMAoperationalENSOpredictionsystem.Thenewstandardandthethusderivedunifiedsetofre-analyzedhistoricalENSOeventsandassociatedinformationprovideagoodreferenceforbettermonitoringandpredictionoffutureENSOevents.
