Mesoscale simulations of gravity waves during the 2008–2009 major stratospheric sudden warming

Just prior to SSW occurrence, widespread westward propagating GWs are found along the vortex's edge and associated predominantly with major topographical features and strong near-surface winds.

Momentum forcing due to GWs surpasses PW forcing in the upper stratosphere and tends to decelerate the polar westerly jet in excess of 30 m s⁻¹ d⁻¹. With SSW onset, PWs dominate the momentum forcing, providing decelerative effects in excess of 50 m s⁻¹ d⁻¹ throughout the upper polar stratosphere. GWs related to topography become less widespread largely due to incipient wind reversal as the vortex starts to elongate.