Eastward‐Propagating Planetary Waves Prior to the January 2009 Sudden Stratospheric Warming. Issue 11 (7th June 2021)

• Record Type: Journal Article
• Authors: Rhodes, Christian T.; Limpasuvan, Varavut; Orsolini, Yvan J.
• Is Part Of: Journal of geophysical research. Volume 126:Issue 11(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-06-07
• Subjects: Atmospheric physics -- Periodicals; Geophysics -- Periodicals; 551.5
• DOI: 10.1029/2020JD033696
• Languages: English
• ISSNs: 2169-897X

Abstract

Abstract: Eastward‐propagating planetary waves (EPWs) were investigated prior to the boreal January 2009 major sudden stratospheric warming (SSW) event simulated by the National Center for Atmospheric Research's Whole Atmosphere Community Climate Model with specified dynamics. About 22 days before SSW onset, a background flow with jet maxima around the upper polar stratosphere and subtropical mesosphere developed due to the net forcing by gravity and planetary waves. The mesospheric wind structure was largely unstable and supported a wave geometry conducive to overreflection. With a zonal phase speed of ∼10 m s −1, EPWs appeared near their turning and critical layers as wavenumber‐2 perturbations in the stratosphere and mesosphere. Accompanied by upward EPW activity from the lower stratosphere, EPW growth exhibited characteristics of wave instability and overreflection. Key Points: Planetary and gravity wave forcings create eastward wind maxima in the stratosphere and mesosphere before sudden stratospheric warming onset This double‐maxima wind configuration favors planetary wave growth from wind shear instability via overreflection The refractive index of the wintertime middle atmosphere is conducive to the production of eastward‐propagating planetary waves