CirculationPatternsLinkedtothePositiveSub-TropicalIndianOceanDipoleChibuikeChiedozieIBEBUCHI*InstituteofGeographyandGeology,UniversityofWürzburg,AmHubland97074Würzburg,Germany(Received29January2022;revised14April2022;accepted18May2022)ABSTRACTThepositivephaseofthesubtropicalIndianOceandipole(SIOD)isoneoftheclimaticmodesinthesubtropicalsouthernIndianOceanthatinfluencestheaustralsummerinter-annualrainfallvariabilityinpartsofsouthernAfrica.Thispaperexaminesaustralsummerrain-bearingcirculationtypes(CTs)inAfricasouthoftheequatorthatarerelatedtothepositiveSIODandthedynamicsthroughwhichspecificrainfallregionsinsouthernAfricacanbeinfluencedbythisrelationship.Fouraustralsummerrain-bearingCTswereobtained.AmongthefourCTs,theCTthatfeatured(i)enhancedcyclonicactivityinthesouthwestIndianOcean;(ii)positivewidespreadrainfallanomalyinthesouthwestIndianOcean;and(iii)low-levelconvergenceofmoisturefluxesfromthetropicalSouthAtlanticOcean,tropicalIndianOcean,andthesouthwestIndianOcean,overthesouth-centrallandmassofAfrica,wasfoundtoberelatedtothepositiveSIODclimaticmode.TherelationshipalsoimpliesthatpositiveSIODcanbeexpectedtoincreasetheamplitudeandfrequencyofoccurrenceoftheaforementionedCT.ThelinkagebetweentheCTrelatedtothepositiveSIODandaustralsummerhomogeneousregionsofrainfallanomaliesinAfricasouthoftheequatorshowedthatitistheprincipalCTthatisrelatedtotheinter-annualrainfallvariabilityofthesouth-centralregionsofAfrica,wheretheSIODisalreadyknowntosignificantlyinfluenceitsrainfallvariability.Hence,throughthelarge-scalepatternsofatmosphericcirculationassociatedwiththeCT,theSIODcaninfluencethespatialdistributionandintensityofrainfalloverthepreferredlandmassthroughenhancedmoistureconvergence.Keywords:subtropicalIndianOceandipole,circulationtypes,rainfall,SouthIndianOcean,moistureconvergenceCitation:Ibebuchi,C.C.,2023:Circulationpatternslinkedtothepositivesub-tropicalIndianOceandipole.Adv.Atmos.Sci.,40(1),110−128,https://doi.org/10.1007/s00376-022-2017-2.ArticleHighlights:•Thepositive...
