Influence of QBO-MJO connection on the turbulence variation in the TTL observed with equatorial atmosphere radar

Abstract

Atmospheric turbulence triggers vertical transport of heat and material exchange within troposphere and the stratosphere known as Stratosphere-Troposphere Exchange (STE). This phenomenon occurs in Tropical Tropopause Layer (TTL), a transition layer within 14-18.5 km. The state of TTL is the key to understand how phenomena in the troposphere and stratosphere interact. The interaction between Quasi-Biennial Oscillation (QBO), a zonal wind oscillation in stratosphere, and Madden-Julian Oscillation (MJO) defined as an eastward moving disturbance of convective system in the previous study is closely linked in boreal winter. This study presents the variation of turbulence intensity toward QBO-MJO interaction in TTL calculated from spectral width observed with Equatorial Atmosphere Radar (EAR) located in Agam, West Sumatra (0.2°S, 100.32°E). Analysis is focused on the extended boreal winter period. Turbulence intensity (σturb) in TTL tends to have an inversely proportional value toward zonal wind in 50 hPa. Generally, enhancement of turbulence intensity is observed on active phase MJO. Zonal wind and vertical wind are stronger in active phase MJO occurred in QBOE than QBOW that can lead to increase turbulence intensity in TTL. These parameters intensification is associated with stronger convective and precipitation system during QBOE-MJO that is caused by more unstable atmosphere.