Theeddytrackingapproachisdevelopedusingtheglobalnearestneighborfilter(GNNF)toinvestigatetheevolutionprocessesandbehaviorsofmesoscaleeddiesintheSouthChinaSea(SCS).CombiningtheKalmanfilterandoptimaldataassociationtechnologies,theGNNFalgorithmisabletoreducepairingerrorsto0.2%intrackingsyntheticeddytracks,outperformingotherexistingmethods.Atotalof4913eddytracksthatlastmorethanaweekareobtainedbytheGNNFduring1993–2012.Theanalysisofagrowthandadecaybasedon3445simpleeddytracksshowthateddyradius,amplitude,andvorticitysmoothlyincreaseduringthefirsthalfoflifetimeanddeclineduringthesecondhalffollowingaparabolaopeningdownwards.ThegenesisofeddiesmainlyclustersnorthwestandsouthwestofLuzonIslandwhereasthedissipationsconcentratetheXishaIslandswheretheunderwaterbaytrapsandterminateseddies.WestoftheLuzonStrait,northwestofLuzonIsland,andsoutheastofVietnamareregionswhereeddysplitsandmergersarefrequentlyobserved.Shortdisappearancesmainlydistributeinthefirsttworegions.Moreover,eddysplitsgenerallyresultinadecreaseoftheradiusandtheamplitudewhereaseddymergersinducegrowingup.Eddyintensityandvorticity,onthecontrary,arestrengthenedintheeddysplitsanddiminishedinmergers.
