Interaction between Planetary Wave and Gravity Waves in the Middle Atmosphere

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• Professor Hye-Yeong Chun, Department of Atmospheric Sciences, Yonsei University
• Thursday 21 April 2022, 11:00-12:00
• British Antarctic Survey.

If you have a question about this talk, please contact Alison Ming.

CCfCS curated talk from BAS AIC seminar series

Both planetary waves (PWs) and gravity waves (GWs) play important role in atmospheric dynamics. Interaction between PWs and GWs in the middle atmosphere is investigated in two aspects: (i) In situ generation of PWs forced by non-conservative GW drag (GWD) forcing term in the linearized quasi-geostrophic potential vorticity equation, and (ii) compensation between PW forcing and orographic GWD in the northern winter stratosphere through baroclinic instability. The first topic is applied to a vortex split-type stratospheric sudden warming (SSW) event that occurred in January 2009. The result demonstrates that the amplification of the PWs of zonal wavenumber 2 in the stratosphere before the onset of 2009 SSW is due to the downward-propagating transient PWs of zonal wavenumber 2 that are generated by non-conservative GW forcing from above. The second topic is investigated to examine whether the compensation between PW forcing and orographic GWD that revealed from some idealized general circulation model studies appears in the real atmosphere using reanalysis data for 32 years in the northern winter. It is found that in-situ generation of PWs and the refractive-index modification occur simultaneously in the compensation processes, with stronger contribution by the refractive-index modification for weak orographic GWD cases.

Biography: Hye-Yeong did her PhD in 1991 at North Carolina State University in USA on critical-level dynamics of atmospheric gravity waves forced by diabatic forcing both in theoretical and numerical modelling aspects. She then moved to GSFC /NASA as a postdoc focusing on solitary wave dynamics. After she returned to Korea and joined to Yonsei University as a professor, she worked on parameterization of convective gravity waves for use in climate models and mesoscale simulation of convective gravity waves. Since 2006, she also has worked on aviation turbulence in the free atmosphere. She served as a Dean of the University College of Yonsei University and President of Korean Meteorological Society. Her recent research interests include PW-GW interaction and QBO dynamics, specifically QBO disruptions.

This talk is part of the Cambridge Centre for Climate Science series.

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