Thispaperpresentsastudyondragcoefficientsundertyphoonwindforcingbasedonobservationsandnumericalexperiments.ThefrictionvelocityandwindspeedaremeasuredatamarineobservationplatformintheSouthChinaSea.Threetyphoons:SOULIK(2013),TRAMI(2013)andFITOW(2013)areobservedatabuoystationinthenortheastseaareaofPingtanIsland.Anewparameterizationisformulatedforthewinddragcoefficientasafunctionofwindspeed.Itisfoundthatthedragcoefficient(Cd)increaseslinearlywiththeslopeof0.083?10?3forwindspeedlessthan24ms?1.Toinvestigatethedragcoefficientunderhigherwindconditions,threenumericalexperimentsareimplementedforthesethreetyphoonsusingSWANwavemodel.Thewindinputdataareobjectivereanalysisdatasets,whichareassimilatedwithmanysourcesandprovidedeverysixhourswiththeresolutionof0.125°×0.125°.Thenumericalsimulationresultsshowagoodagreementwithwaveobservationdataundertyphoonwindforcing.Theresultsindicatethatthedragcoefficientlevelsoffwiththelinearslopeof0.012?10?3forhigherwindspeeds(lessthan34ms?1)andthenewparameterizationimprovesethesimulationaccuracycomparedwiththeWu(1982)defaultusedinSWAN.
