Enhanced stratosphere/troposphere coupling during extreme warm stratospheric events with strong polar-night jet oscillation

Loading...
Thumbnail Image
Date
2018
Volume
9
Issue
12
Journal
Series Titel
Book Title
Publisher
Basel : MDPI AG
Link to publishers version
Abstract

Extreme warm stratospheric events during polar winters from ERA-Interim reanalysis and CMIP5-ESM-LR runs were separated by duration and strength of the polar-night jet oscillation (PJO) using a high statistical confidence level of three standard deviations (strong-PJO events). With a composite analysis, we demonstrate that strong-PJO events show a significantly stronger downward propagating signal in both, northern annular mode (NAM) and zonal mean zonal wind anomaly in the stratosphere in comparison with non-PJO events. The lower stratospheric EP-flux-divergence difference in ERA-Interim was stronger in comparison to long-term CMIP5-ESM-LR runs (by a factor of four). This suggests that stratosphere-troposphere coupling is stronger in ERA-Interim than in CMIP5-ESM-LR. During the 60 days following the central date (CD), the Arctic oscillation signal was more intense during strong-PJO events than during non-PJO events in ERA-Interim data in comparison to CMIP5-ESM-LR runs. During the 15-day phase after CD, strong PJO events had a significant increase in stratospheric ozone, upper tropospheric zonally asymmetric impact, and a regional surface impact in ERA-Interim. Finally, we conclude that the applied high statistical threshold gives a clearer separation of extreme warm stratospheric events into strong-PJO events and non-PJO events including their different downward propagating NAM signal and tropospheric impacts. © 2018 by the authors.

Description
Keywords
Arctic oscillation, CMIP5, EP-flux divergence, ERA-Interim, Major sudden stratospheric warmings, MPI-ESM-LR, Northern annular mode, Polar-night jet oscillation, Warm stratospheric events, Ozone layer, Troposphere, Arctic Oscillation, CMIP5, Era interims, Flux divergences, Northern annular mode, Polar-night jet, Stratospheric warmings, Warm stratospheric events, Climate models, Arctic Oscillation, CMIP, coupling, extreme event, jet, stratosphere-troposphere interaction, sudden stratospheric warming, zonal wind
Citation
Peters, D. H. W., Schneidereit, A., & Karpechko, A. Y. (2018). Enhanced stratosphere/troposphere coupling during extreme warm stratospheric events with strong polar-night jet oscillation. 9(12). https://doi.org//10.3390/atmos9120467
License
CC BY 4.0 Unported