Strong Polar Vortex (SPV) Variability
Analysis of Intense Vortex States - SD4SP Project
Strong Polar Vortex (SPV) Events
While SSWs represent the breakdown of the vortex, Strong Polar Vortex (SPV) events consist of periods where the stratospheric jet is exceptionally intense and the polar temperatures are unusually low. These states often lead to a positive NAO phase, characterized by milder and stormier conditions in Northern Europe.
SPV Event List
Dates indicate the onset of peak intensity for each identified event.
| Event # | Date | Event # | Date |
|---|---|---|---|
| 1 | 24 Jan 1957 | 24 | 3 Feb 1989 |
| 2 | 13 Mar 1960 | 25 | 14 Jan 1991 |
| 3 | 7 Feb 1961 | 26 | 27 Jan 1993 |
| 4 | 23 Jan 1962 | 27 | 28 Feb 1994 |
| 5 | 6 Apr 1962 | 28 | 7 Feb 1996 |
| 6 | 30 Jan 1964 | 29 | 3 Feb 1997 |
| 7 | 23 Jan 1965 | 30 | 1 Mar 1997 |
| 8 | 26 Jan 1967 | 31 | 22 Mar 1997 |
| 9 | 25 Feb 1967 | 32 | 17 Apr 1997 |
| 10 | 18 Mar 1967 | 33 | 17 Jan 2005 |
| 11 | 17 Feb 1972 | 34 | 15 Feb 2007 |
| 12 | 18 Jan 1974 | 35 | 7 Jan 2009 |
| 13 | 8 Feb 1974 | 36 | 9 Feb 2011 |
| 14 | 11 Jan 1976 | 37 | 5 Mar 2011 |
| 15 | 5 Feb 1976 | 38 | 12 Apr 2013 |
| 16 | 9 Mar 1976 | 39 | 11 Mar 2015 |
| 17 | 7 Feb 1980 | 40 | 20 Jan 2016 |
| 18 | 15 Jan 1981 | 41 | 16 Feb 2016 |
| 19 | 7 Jan 1983 | 42 | 11 Mar 2019 |
| 20 | 22 Jan 1984 | 43 | 14 Jan 2020 |
| 21 | 22 Dec 1985 | 44 | 13 Feb 2020 |
| 22 | 7 Feb 1988 | 45 | 6 Mar 2020 |
| 23 | 4 Jan 1989 |
Downward Propagation: Strong Vortex
These figures illustrate the persistent downward coupling during SPV events. In contrast to SSWs, the NAM anomalies remain positive, strengthening the tropospheric jet stream.
Figure 1: Composite downward propagation of NAM anomalies for SPV events. SD4SP project GA:101065820