1. Page 1© Crown copyright 2007 Influence of ENSO on European Climate via the Stratosphere Sarah Ineson and Adam Scaife 2007

2. Page 2© Crown copyright 2007 Stratospheric response to El Niño Hamilton, 1993

3. Page 3© Crown copyright 2007 Impact of 1940-42 El Niño on Europe Brönnimann et al., 2004

4. Page 4© Crown copyright 2007 Experiment design L60 HadGAM1 with observed SST 4-member ensemble 1960-2002 ENSO based on DJF Niño3 SST anomaly: Warm: 1965/66, 72/73, 82/83, 86/87, 91/92, 97/98 Cold: 1967/68, 70/71, 73/74, 75/76, 84/85, 88/89, 99/00 warm (cold) years – neutral years

5. Page 5© Crown copyright 2007 DJF stationary wave anomaly at 50°N Manzini et al., 2006 L60 HadGAM1MA-ECHAM5ERA40

6. Page 6© Crown copyright 2007 Model vs observed response to warm ENSO events DJF geopotential height, Z, 46hPa ModelObservations (Hamilton, 1993)

7. Page 7© Crown copyright 2007 Downward progression Manzini et al., 2006 L60 HadGAM

8. Page 8© Crown copyright 2007 Composite model surface response to El Niño Jan-Feb PMSLJan-Feb T2m

9. Page 9© Crown copyright 2007 Intra-seasonal variability: PMSL NovDecFebJan Moron and Gouirand, IJC, 2003 The negative NAO signal appears in late winter in both model and obs.

10. Page 10© Crown copyright 2007 Intra-seasonal variability: T2m Nov Dec Jan Feb Mar Apr Corresponding cold European signal in late winter, persists into Spring

11. Page 11© Crown copyright 2007 L38 HadGAM1 vs L60 HadGAM1 vertical resolution

12. Page 12© Crown copyright 2007 High Lid – Low Lid HadGAM1 comparison L60 HadGAM1L38 HadGAM1 (standard resolution) DJF Z46hPa composite for El Niño events, 1982/83, 1986/87, 1991/92, 1997/98

13. Page 13© Crown copyright 2007 High Lid - Low Lid HadGAM1 comparison Jan-Feb PMSL composite for El Niño events, 1982/83, 86/87, 91/92, 97/98 L60 HadGAM1L38 HadGAM1 (standard resolution)

14. Page 14© Crown copyright 2007 Summary of mechanism Model reproduces observed infilling of the stratospheric polar cyclone associated with El Niño Better stratospheric response in L60 than L38 model Negative NAO and cold European surface response in later winter as in observations Potential increased capability in seasonal prediction for Europe in winter

15. Page 15© Crown copyright 2007 DJF stationary eddy height anomaly at 500hPa L60 HadGAM1 Manzini et al., 2006 MA-ECHAM5ERA40

16. Page 16© Crown copyright 2007 Model NH stratospheric response to QBO Z46 hPa +ve QBO-ve QBO U46 hPa (10°N -10°S)

17. Page 17© Crown copyright 2007 Model response to warm and cold ENSO composites DJF geopotential height, Z, 46hPa WarmCold

18. Page 18© Crown copyright 2007 Figure 3. January MSLP response for (a) ELN – CTRL for standard stratosphere, (b) ELN –CTRL for degraded stratosphere and (c) the difference between the responses due to the inclusion of stratospheric variability. Units are in hPa. (b) (a) (c) Figure 3. January MSLP response for (a) ELN – CTRL for standard stratosphere, (b) ELN –CTRL for degraded stratosphere and (c) the difference between the responses due to the inclusion of stratospheric variability. Units are in hPa. (b) (a) (c) Figure 3. January MSLP response for (a) ELN – CTRL for standard stratosphere, (b) ELN –CTRL for degraded stratosphere and (c) the difference between the responses due to the inclusion of stratospheric variability. Units are in hPa. (b) (a) (c) ENSO teleconnections in European winter Chris Bell and Lesley Gray, University of Reading standard stratospheredegraded stratosphere

19. Page 19© Crown copyright 2007 Toniazzo and Scaife, 2006 Impact of El N i ño on North Atlantic climate Moderate Strong January-February PMSL anomaly