Group seminar on 19. December, 15:00 CET
The QBO Dynamics and Gravity Waves Characteristics as Seen in ERA5 Reanalysis
Hamid A. Pahlavan
The quasi-biennial oscillation (QBO) is the primary mode of interannual variability in the tropical stratosphere, with links to subseasonal-to-seasonal forecast skills. It is characterized by the downward propagation of successive westerly and easterly wind regimes with an average period of about 28 months. Using ERA5 reanalysis data, this talk further investigates the dynamics of the QBO and the characteristics of waves driving it. Because of ERA5’s higher spatial resolution compared to its predecessors, it is capable of resolving a broader spectrum of atmospheric waves and allows for a better representation of the wave–mean flow interactions, both of which are of crucial importance for QBO studies. In particular, I will focus on four main topics: i) explaining the QBO and its momentum budget, ii) analyzing the contributions of different types of waves to the driving of the QBO, iii) characterizing the convectively generated gravity waves in the tropics, and iv) observing the properties of gravity waves as they propagate upward through the stratosphere during opposing phases of the QBO.