984 Rossby Wave Propagation into the Northern Hemisphere Stratosphere: The Role of Zonal Phase Speed

Wednesday, 9 January 2019
Hall 4 (Phoenix Convention Center - West and North Buildings)
Daniela I. V. Domeisen, ETH, Zurich, Switzerland; and O. Martius and B. Jiménez-Esteve

Handout (690.5 kB)

Sudden stratospheric warming (SSW) events are to a dominant part induced by upward propagating planetary waves. While theory predicts that the zonal phase speed of a tropospheric wave forcing affects wave propagation into the stratosphere, its relevance for SSW events has so far not been considered. This study shows in a linear wave diagnostic and in reanalysis data that phase speeds tend eastward as waves propagate upward, indicating that the stratosphere preselects eastward phase speeds for propagation, especially for zonal wave number 2. This also affects SSW events: Split SSW events tend to be preceded by anomalously eastward zonal phase speeds. Zonal phase speed may indeed explain part of the increased wave flux observed during the preconditioning of SSW events, as, for example, for the record 2009 SSW event.

Supplementary URL: https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2017GL076886

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