Conversion Characteristics between Barotropic and Baroclinic Circulations of the SAH in Its Seasonal Evolution

In the context of 1958-1997 NCFP NCAR re-analyses, the South Asia high (SAH) was divided into two components, barotropic and haroclinic, the former based on mass weighed vertical integration and the latter on the difference between the measured circulation and the barotropic component counterpart, whereupon the barotropic and baroclinic circulation conversion features were addressed of the research SAH during its seasonal variation. Evidence suggests that i) in summer (winter). the SAH is a thermal (dynamical) system. with dominant baroclinicity (barotropicity). either of the components accounting for approximately 70% of the total contribution; ii) as time progresses from winter to summer, accompanied by the barotropic SAH evolving into its baroclinic analog, the SAH is moving under the" thermal guidance" of its baroclinic component circulation, suggesting that the component circulation precedes the system itself in variation. iii) the reversal happens when it goes from summer to winter, with the SAH displacement under the" dynamic steering" of its barotropic component circulation.