Alinearstabilityanalysisisperformedforaplumeflowinsideacylinderofaspectratio1.TheconfigurationisidenticaltothatusedbyLopezandMarques(2013)fortheirdirectnumericalsimulationstudy.Itisfoundthatthefirstbifurcation,whichleadstoaperiodicaxisymmetricflowstate,isaccuratelypredictedbylinearanalysis:boththecriticalRayleighnumberandtheglobalfrequencyareconsistentwiththereportedDNSresults.Itisfurthershownthatpressurefeedbackdrivestheglobalmode,ratherthanabsoluteinstability.
