Premium
Rossby Wave Propagation into the Northern Hemisphere Stratosphere: The Role of Zonal Phase Speed
Author(s) -
Domeisen Daniela I. V.,
Martius Olivia,
JiménezEsteve Bernat
Publication year - 2018
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 - 10.1002/2017gl076886
Subject(s) - stratosphere , forcing (mathematics) , rossby wave , northern hemisphere , geology , phase velocity , phase (matter) , sudden stratospheric warming , climatology , troposphere , wave propagation , atmospheric sciences , geophysics , physics , polar vortex , quantum mechanics
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.