The influence of natural and anthropogenic factors on major stratospheric sudden warmings.

Hansen, Felicitas , Matthes, Katja , Petrick, Christof and Wang, Wuke (2014) The influence of natural and anthropogenic factors on major stratospheric sudden warmings. Open Access Journal of Geophysical Research: Atmospheres, 119 (13). pp. 8117-8136. DOI 10.1002/2013JD021397.

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Major stratospheric sudden warmings are prominent disturbances of the Northern Hemisphere polar winter stratosphere. Understanding the factors controlling major warmings is required, since the associated circulation changes can propagate down into the troposphere and affect the surface climate, suggesting enhanced prediction skill when these processes are accurately represented in models. In this study we investigate how different natural and anthropogenic factors, namely, the quasi-biennial oscillation (QBO), sea surface temperatures (SSTs), anthropogenic greenhouse gases, and ozone-depleting substances, influence the frequency, variability, and life cycle of major warmings. This is done using sensitivity experiments performed with the National Center for Atmospheric Research's Community Earth System Model (CESM). CESM is able to simulate the life cycle of major warmings realistically. The QBO strengthens the climatological stratospheric polar night jet (PNJ) and significantly reduces the frequency of major warmings through reduction of planetary wave propagation into the PNJ region. Variability in SSTs weakens the PNJ and significantly increases the major warming frequency due to enhanced wave forcing. Even extreme climate change conditions (RCP8.5 scenario) do not influence the total frequency but determine the prewarming phase of major warmings. The amplitude and duration of major warmings seem to be mainly determined by internal stratospheric variability. We also suggest that SST variability, two-way ocean/atmosphere coupling, and hence the memory of the ocean are needed to reproduce the observed tropospheric negative Northern Annular Mode pattern after major warmings.

Document Type: Article
Additional Information: korrekte ISSN für die Unterreihe: 2169-897X - WOS:000340408000021
Keywords: stratospheric sudden warmings; stratosphere-troposphere coupling; QBO influence on SSWs; SST influence on SSWs
Research affiliation: OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-ME Maritime Meteorology
Refereed: Yes
Open Access Journal?: No
Publisher: AGU (American Geophysical Union), Wiley
Projects: Future Ocean
Date Deposited: 06 Aug 2014 11:03
Last Modified: 28 Jun 2019 08:29

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