[A-AS09] Stratosphere-troposphere Processes And their Role in Climate

[AAS09-P11] Sea-land-breeze gravity waves robustizing equatorial stratospheric QBO: 2. Coastal diurnal cycle exciting super-annual cycle

*Manabu D. Yamanaka^1,2,3, Shin-Ya Ogino³ (1.Research Institute for Humanity and Nature, 2.Professor Emeritus of Kobe University, 3.Japan Agency for Marine-Earth Science and Technology)

Keywords:quasi-biennial oscillation, diurnal-cycle sea-land breeze circulation, Earth-ocean-atmosphere interaction

The quasi-biennial oscillation (QBO) appears robustly in the stratosphere, where in situ thermal forcing is weak. The strongest thermal forcing on the equatorial lands with diurnal cycle (DC) drives the sea-land breeze circulations (SLBCs) centered at the Indonesian maritime continent (IMC) with the longest coastline, which organize convective clouds making atmospheric energy equilibrium and water cold trap. In Part 1 we have shown that SLBCs are the selective absorption of bidirectional (land-/sea-ward) waves produces directly 30% of the mean zonal acceleration of QBO. The momentum absorbed locally may generate also longer waves contributing to the remainder of zonal acceleration. Because of “pair production” the bidirectional wave momenta are equi-amplitude, determined with land-sea contrast, and their zonal components are dependent on the angle between a coastline and the meridian.