MECHANISM OF VARIATION OF ZONAL AVAILABLE POTENTIAL ENERGY AND ZONAL KINETIC ENERGY

While the generation of zonal available potential energy increases due to zonally averaged heating and transfer of available potential energy to eddies decreases, zonally available potential energy raises and reduces in reverse. This is the main mechanism for the index cycle oscillations of zonal available potential energy variation. The interaction between zonally averaged and eddies available potential energy presents mechanism for the short-range oscillations.