GEOPHYSICAL RESEARCH LETTERS

Supporting Information for “How well do we know
the surface impact of sudden stratosphericwarmings?”
Jessica Oehrlein1,2 , Lorenzo M. Polvani2,3,4 , Lantao Sun5 , Clara Deser6
1 Dept. of Mathematics, Fitchburg State University

2 Dept. of Applied Physics and Applied Mathematics, Columbia University

3 Dept. of Earth and Environmental Sciences, Columbia University

4 Lamont-Doherty Earth Observatory

5 Dept. of Atmospheric Sciences, Colorado State University

6 National Center for Atmospheric ResearchContents of this file
1. Figures S1 to S7
2. Table S1
In this supplementary section, we show statistics of our bootstrapping procedure overall(Figure S1) and for particular composites of interest (Table S1). We show the 10th and90th percentile surface responses with corresponding Northern Annular Mode plots forfour of those regions (Figures S2 and S3), complementing a parallel figure for the other two

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X-2:regions shown in Figure 3. We consider any impact on the El Niño-Southern Oscillationon our results in the North Pacific (Figure S4). Finally, we consider how the spread insurface responses relates to the spread in stratospheric anomalies at different pressurelevels and time lags (Figures S5 and S6).

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:X-3

Figure S1. Distributions across all 2000 composites of a) the number of distinct events in eachbootstrapped composite and b) the maximum number of occurrences of a single event in eachcomposite.

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X-4

Figure S2.

:

As in Figure 3, but for North Pacific sea level pressure (a-d) and North Atlantic

precipitation (e-h).

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:Figure S3.

X-5

As in Figure 3, but for Northern Eurasian (a-d) and Eastern US (e-h) surface

temperature.

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X-6Table S1.

:

The number of occurrences of each SSW events in the 10th and 90th percentile

composites for the regions of interest.
Event
NAO 10th NAO 90th E. Canada 10th E. Canada 90th30 Jan 1958
101117 Jan 1960301
130 Jan 1963
103218 Dec 1965
011423 Feb 1966
21027 Jan 1968
201029 Nov 1968
211
12 Jan 1970
112118 Jan 1971
202020 Mar 1971
000231 Jan 1973
01209 Jan 1977
330022 Feb 1979
000129 Feb 1980
11016 Feb 1981
02134 Mar 1981
10024 Dec 1981
110024 Feb 1984
22201 Jan 1985
202023 Jan 1987
11108 Dec 1987
010214 Mar 1988
02
1421 Feb 1989
101115 Dec 1998
121026 Feb 1999
212120 Mar 2000
001311 Feb 2001
111031 Dec 2001
131118 Jan 2003
102
15 Jan 2004
213121 Jan 2006
000224 Feb 2007
131122 Feb 2008
011024 Jan 2009
12009 Feb 2010
021124 Mar 2010
02007 Jan 2013
311012 Feb 201800202 Jan 2019
0200October 10, 2021, 4:24pm

:Figure S4.

X-7

As in Figure 4c, but grouped by ENSO phase: (a) all phases, (b) neutral ENSO,(c) El Niño (EN), and (d) La Niña (LN). SLP anomalies after SSWs are shown in unfilled bars;
those after 0-60 day periods across all winters (of that phase where applicable) are hatched.

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X-8

Figure S5.

:

As in Figure 5, but for stratospheric polar vortex strength calculated at 100 hPa.

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:Figure S6.

X-9

Correlations at each pressure and lag between a five-day geopotential heightanomaly and the 0-60 day surface response.

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