简介：BasedonGlobalOceanDataAssimilationSystem(GODAS)andNCEPreanalysisdata,atmosphericandoceanicprocessespossiblyresponsiblefortheonsetofthe2011/12LaNiaevent,whichfollowedthe2010/11LaNiaeven—referredtoasa'doubledip'LaNia—areinvestigated.Thekeymechanismsinvolvedinactivatingthe2011/12LaNiaareillustratedbythesedatasets.ResultsshowthatneutralconditionswerealreadyevidentintheequatorialeasternPacificduringthedecayingphaseofthe2010/11LaNia.However,isothermalanalysesshowobviouslycoldwaterstillpersistingatthesurfaceandatsubsurfacedepthsinoff-equatorialregionsthroughoutearly2011,beingmostpronouncedinthetropicalSouthPacific.ThenegativeSSTanomaliesinthetropicalSouthPacificactedtostrengthenasouthernwindacrosstheequator.ThesubsurfacecoldwaterinthetropicalSouthPacificthenspreadnorthwardandbrokeintotheequatorialregionatthethermoclinedepth.Thisincursionprocessofoff-equatorialsubsurfacecoldwatersuccessfullyinterruptedtheeasternpropagationofwarmwateralongtheequator,whichhadpreviouslyaccumulatedatsubsurfacedepthsinthewarmpoolduringthe2010/11LaNiaevent.Furthermore,theincursionprocessstrengthenedasaresultoftheoff-equatorialeffects,mostlyinthetropicalSouthPacific.ThenegativeSSTanomaliesthenreappearedinthecentralbasininsummer2011,andactedtotriggerlocalcoupledair–seainteractionstoproduceatmospheric–oceanicanomaliesthatdevelopedandevolvedwiththesecondcoolinginthefallof2011.