In the context of the 1958-1997 NCEP/NCAR reanalyses,the south Asian high(SAH) is vertically divided into two components,barotropic and baroclinic circulations,whereupon the conversion features are addressed of the SAH during its seasonal variation.Evidence suggests that 1)in summer(winter),the SAH is dominant by the baroclinic(barotropic) component accounting for approximately 70% of the total contribution; 2) as time progresses from winter to summer,accompanied by the barotropic SAH evolving into its baroclinic analog,the SAH moves under the guidance of its baroclinic component circulation,suggesting that the baroclinic component circulation precedes the system itself in variation; 3) the reversal happens when it goes from summer to winter,with the SAH displacement under the steering of its barotropic component circulation.