Comparing and contrasting extreme stratospheric events, including their coupling to the tropospheric circulation ...

• Main Authors: Dunn-Sigouin, Etienne, Shaw, Tiffany Ann
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Columbia University 2015
• Subjects: Troposphere; Atmospheric thermodynamics; Stratosphere; Polar vortex; Geophysics; FOS: Earth and related environmental sciences; Atmosphere; North Atlantic
• Online Access: https://dx.doi.org/10.7916/d8m9083c; https://academiccommons.columbia.edu/doi/10.7916/D8M9083C

Recent work has emphasized the importance of stratosphere-troposphere coupling associated with extreme values of the polar vortex strength and stratospheric planetary wave heat flux during Northern Hemisphere winter. Here using ERA-Interim reanalysis data the evolution of the two types of events are compared. The life cycle of total (anomaly plus climatology) positive/negative heat flux events are associated with vertically deep high-latitude planetary wave structures and exhibit largely equal but opposite-signed impacts, including a net deceleration/acceleration of the polar vortex due to EP flux convergence/divergence and an equatorward/poleward tropospheric jet shift in the North Atlantic. The tropospheric wave pattern is westward propagating. High-latitude stratospheric vertical zonal wind shear plays a key role during both events. A comparison of the stratospheric events reveals that planetary wave events contribute to the development of vortex events. In particular, total negative heat flux events ...