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Interaction Between Stratospheric Kelvin Waves and Gravity Waves in the Easterly QBO Phase
Author(s) -
Kim YoungHa,
Achatz Ulrich
Publication year - 2021
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2021gl095226
Subject(s) - kelvin wave , stratosphere , quasi biennial oscillation , gravitational wave , physics , gravity wave , amplitude , geophysics , atmospheric sciences , meteorology , optics , astrophysics
Abstract A general circulation model is used to study the interaction between parameterized gravity waves (GWs) and large‐scale Kelvin waves in the tropical stratosphere. The simulation shows that Kelvin waves with substantial amplitudes (∼10 m s −1 ) can significantly affect the distribution of GW drag by modulating the local shear. Furthermore, this effect is localized to regions above strong convective organizations that generate large‐amplitude GWs, so that at a given altitude it occurs selectively in a certain phase of Kelvin waves. Accordingly, this effect also contributes to the zonal‐mean GW drag, which is large in the middle stratosphere during the phase transition of the quasi‐biennial oscillation (QBO). Furthermore, we detect an enhancement of Kelvin‐wave momentum flux due to GW drag modulated by Kelvin waves. The result implies an importance of GW dynamics coupled to Kelvin waves in the QBO progression.