12Supplemental Material

34
5

The Role of the North Atlantic Oscillation in European Climate Projections

67

Clara Deser*, James W. Hurrell and Adam S. Phillips

89Climate and Global Dynamics Division

10National Center for Atmospheric Research

11Boulder CO, USA

12
13

Submitted to Climate Dynamics

1414 July 2016

15

Revised 1 December 2016

16
17
18

*Corresponding author address: Dr. Clara Deser, Climate and Global Dynamics

19Division, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO

2080307 USA. Email: cdeser@ucar.edu Tel: 303-497-1359; Fax: 303-497-1333.

2122232425

Figure S1. Winter SAT (°C per 30 years; color shading) and SLP (contour interval is 1hPa per 30 years with negative values dashed) trends during 2016-45 from each of the 40
members of the CESM1 Large Ensemble.

26
27
28

Figure S2. As in Fig. S1 but for SLP and precipitation (mm day-1 per 30 years).

2930
3132
33
3435

Figure S3. Future 50-year trends (2016-2065) in winter (a, b) SAT (°C per 50 years;
color shading) and (c, d) precipitation (mm day-1 per 50 years; color shading) fromsimulations 31 and 19 of the CESM1 Large Ensemble, chosen for their contrasting
SLP trends (contours; interval = 1hPa per 50 years with negative values dashed).

3637
38
3940
41424344

Figure S4. Impact of the NAO on 50-year future climate trends (2016-2065). (a)Regressions of winter SLP and SAT trends upon the normalized leading PC of winter
SLP trends in the CESM1 Large Ensemble (multiplied by two); (b) CESM1 ensemblemean winter SLP and SAT trends; (c) b - a; (d) b + a. SAT in color shading (°C per 50years) and SLP in contours (interval = 1 hPa per 50 years with negative values
dashed.) Panels e-h as in a-d but for precipitation (mm day-1 per 50 years) in placeof SAT.

45464748
49
5051Figure S5. Interannual statistics of the NAO in observations (Obs) and each member (140) of the CESM1 Large Ensemble. (a) Percent variance explained by the leading EOF ofNorth Atlantic winter SLP based on detrended data during 1920-2012. (b) One-year lag
autocorrelation of the associated PC timeseries. The value at the upper right of each paneldenotes the average over the 40 ensemble members.

52535455
56
57
585960616263Figure S6. Comparison between the NAO and associated climate impacts in the2600-year CESM1 atmosphere-only control integration computed from interannual
data (scaled as described in the text) and from 30-year trends. (a) Scaledinterannual regressions of winter SLP (contours) and SAT (color shading) anomalies
upon the normalized leading PC of winter SLP anomalies; (b) SLP and SAT trend
regressions upon the normalized leading PC of winter SLP trends; (c) As in (a) butfor precipitation in place of SAT; (d) As in (b) but for precipitation in place of SAT.
SAT in units of °C per 30 years, precipitation in units of mm day-1 per 30 years, andSLP contour interval of 1 hPa per 30 years with negative values dashed.

64
65
66
67
68
69
70
71
72
73
74

Figure S7. As in Fig. S6 but using the CESM1 Large Ensemble. (a) Ensemble-mean ofscaled-interannual regressions of winter SLP (contours) and SAT (color shading)anomalies upon the normalized leading PC of winter SLP anomalies during 20162045; (b) SLP and SAT trend regressions upon the normalized leading PC of winter
SLP trends based on 2016-2045; (c) As in (a) but for precipitation in place of SAT;(d) As in (b) but for precipitation in place of SAT. SAT in units of °C per 30 years,precipitation in units of mm day-1 per 30 years, and SLP contour interval of 1 hPa
per 30 years with negative values dashed.

75767778

Figure S8. As in Fig. S7 but for scaled-interannual and trend regressions based on theperiod 2016-2055. Units as in Fig. S7 but per 40 years.79808182

Figure S9. As in Fig. S7 but for scaled-interannual and trend regressions based on theperiod 2016-2065. Units as in Fig. S7 but per 50 years.

838485868788
899091Figure S10. Impact of the NAO on future climate trends (2016-2065) based oninterannual statistics of the NAO from observations and the forced response fromthe CESM1 Large Ensemble. (a) and (b) show the expected range of future SLP andSAT trends; (c) and (d) show the expected range of future SLP and precipitation
trends. See text for details. SLP contour interval is 1 hPa per 50 years with negativevalues dashed; SAT (color shading) in units of °C per 50 years; and precipitation(color shading) in units of mm day-1 per 50 years.

92939495

Figure S11. As in Fig. S10 but using the CMIP5 multi-model mean in place of theCESM1 Large Ensemble for the forced trend.