No robust evidence of future changes in major stratospheric sudden warmings: a multi-model assessment from CCMI

Blanca Ayarzagüena (1, 2) , Lorenzo M. Polvani (3) , Ulrike Langematz (4) , Hideharu Akiyoshi (5) , Slimane Bekki (6) , Neal Butchart (7) , Martin Dameris (8) , Makoto Deushi (9) , Steven C. Hardiman (7) , Patrick Jöckel (8) , Andrew Klekociuk (10, 11) , Marion Marchand (6) , Martine Michou (12) , Olaf Morgenstern (13) , Fiona M. O'Connor (7) , Luke D. Oman (14) , David A. Plummer (15) , Laura Revell (16, 17) , Eugene Rozanov (16, 18) , David Saint-Martin (12) , John Scinocca (19) , Andrea Stenke (16) , Kane Stone (20, 21, 22) , Yousuke Yamashita (5, 23) , Kohei Yoshida (9) , Guang Zeng (13)

1 Departamento Fisica de la Tierra, Astronomía y Astrofísica [Madrid]
2 IGEO - Instituto de Geociencias [Madrid]
3 Columbia University [New York]
4 Freie Universität Berlin
5 NIES - National Institute for Environmental Studies
6 STRATO - LATMOS
7 MOHC - Met Office Hadley Centre for Climate Change
8 IPA - DLR Institut für Physik der Atmosphäre
9 MRI - Meteorological Research Institute [Tsukuba]
10 AAD - Australian Antarctic Division
11 ACE-CRC - Antarctic Climate and Ecosystems Cooperative Research Centre
12 CNRM - Centre national de recherches météorologiques
13 NIWA - National Institute of Water and Atmospheric Research [Wellington]
14 GSFC - NASA Goddard Space Flight Center
15 Environment and Climate Change Canada
16 IAC - Institute for Atmospheric and Climate Science [Zürich]
17 Bodeker Scientific
18 PMOD/WRC - Physikalisch-Meteorologisches Observatorium Davos/World Radiation Center
19 CCCma - Canadian Centre for Climate Modelling and Analysis
20 School of Earth Sciences [Melbourne]
21 ARC Centre of Excellence for Climate System Science
22 MIT - Massachusetts Institute of Technology
23 JAMSTEC - Japan Agency for Marine-Earth Science and Technology

Major mid-winter stratospheric sudden warmings (SSWs) are the largest instance of wintertime variability in the Arctic stratosphere. Because SSWs are able to cause significant surface weather anomalies on intra-seasonal time scales, several previous studies have focused on their potential future change, as might be induced by anthropogenic forcings. However, a wide range of results have been reported, from a future increase in the frequency of SSWs to an actual decrease. Several factors might explain these contradictory results, notably the use of different metrics for the identification of SSWs, and the impact of large climatological biases in single-model studies. To bring some clarity, we here revisit the question of future SSWs changes, using an identical set of metrics applied consistently across 12 different models participating in the Chemistry Climate Model Initiative. Our analysis reveals that no statistically significant change in the frequency of SSWs will occur over the 21st century, irrespective of the metric used for the identification of the event. Changes in other SSWs characteristics, such as their duration and the tropospheric forcing, are also assessed: again, we find no evidence of future changes over the 21st century.

Domains: Atmospheric and Oceanic Physics [physics.ao-ph]

Blanca Ayarzagüena, Lorenzo M. Polvani, Ulrike Langematz, Hideharu Akiyoshi, Slimane Bekki, et al.. No robust evidence of future changes in major stratospheric sudden warmings: a multi-model assessment from CCMI. Atmospheric Chemistry and Physics, 2018, 18, pp.11277-11287. ⟨10.5194/acp-18-11277-2018⟩. ⟨insu-01755048⟩