1. Kristina Fröhlich, (DWD), Daniela Domeisen (Univ. Hamburg), Amy Butler (NOAA), Matthias Bittner (MPI), Wolfgang Müller (MPI), Johanna Baehr (Univ. Hamburg)

2. Seasonal forecasts with a climate model: what kind of predictability can we expect? El Ni ñ o as a benchmark Europe as our target region Motivation WWOSC, Montréal, August 18th 2014 2

3. ECHAM6 (Atmosphere) horizontal T63 ~ (1.9°x1.9°) vertical L47 = 47 levels up to 0.01hPa land module JSBACH and hydrological discharge model MPIOM (Ozean) plus sea ice Horizontal: 1.5°, Vertical: 40 levels sea-ice model (dynamic/thermodynamic) OASIS3 (Coupler) WWOSC, Montréal, August 18th 2014 3 Seasonal forecasts with a climate model

4. Preview 1.The components: Predictability of the tropical Pacific/El Niño region and stratospheric variability 2.A possible pathway through the stratosphere 3.Predictability in the North Atlantic / European region WWOSC, Montréal, August 18th 2014 4

5. 5 The Data Reference data  ERA interim and HadCRU SST MPIESM-Model:  Set of 9-Member Ensemble of seasonal forecasts for 1982-2010 with start date in November

6. WWOSC, Montréal, August 18th 2014 6 MPI-ESM performance: troposphere worse skill 9 Members Mean high skill Anomaly Correlation Coefficient of 500hPa geopotential height MPI-ESM vs ERAinterim reanalysis DJF (1982-2010 )

7. WWOSC, Montréal, August 18th 2014 7 MPI-ESM performance: El Niño 1997/98 HadCRU dataset MPI-ESM, November & May Nov 99 May 99 Nov 98 May 98 Nov 97 May 97 Nov 96 time [°C] Tropical Pacific surface temperature anomalies for the 1997/98 El Niño MPI-ESM, Nov start dates Nov 99 May 99 Nov 98 May 98 Nov 97 May 97 Nov 96

8. WWOSC, Montréal, August 18th 2014 8 MPI-ESM performance: stratosphere Standard deviation of the zonal wind [m/s] at 10hPa averaged over DJF for 1982 – 2010. MPI-ESMERAinterim

9. WWOSC, Montréal, August 18th 2014 9 A possible pathway through the stratosphere ? Van Loon & Labitzke (1987) Garfinkel & Hartmann (2008) Manzini et al. (2006)

10. WWOSC, Montréal, August 18th 2014 10 El Niño teleconnection into the stratosphere MPI-ESM ERAinterim DJFM - El Niño composite of geopotential height anomaly 500hPa 10hPa m m

11. WWOSC, Montréal, August 18th 2014 11 Downward propagation of the El Niño warm anomaly 99% confidence interval pressure [hPa] MPI-ESM ensemble mean ERAinterim reanalysis 80°N temperature anomalies averaged over all El Niño winters [cp. Fig 4, Manzini et al. (2006)] K

12. WWOSC, Montréal, August 18th 2014 12 Sudden stratospheric warmings are more frequent for a warm polar stratosphere ERAinterim reanalysis model ensemble members model mean DJF temperature anomalies averaged over stratospheric polar cap (10hPa, 60°-90°N) standard deviation one circle per winter / ensemble member [K]

13. WWOSC, Montréal, August 18th 2014 13 Winter predictability over Europe Anomaly Correlation Coefficient for 500hPa geopotential height DJFM all years (1982 - 2011) worse skill high skill

14. WWOSC, Montréal, August 18th 2014 14 Winter predictability over Europe Anomaly Correlation Coefficient for 500hPa geopotential height El Niño SSW El Niño with SSW El Niño w/o SSW worse skill high skill DJFM

15.  El Niño events as well as sudden stratospheric warmings are well described in the MPI-ESM seasonal prediction system  During El Niño years we can confirm earlier studies on the connection of the El Niño region, the North Pacific and the stratosphere sudden stratospheric warming events are more frequent for a warm polar stratosphere winter predictability over Europe is shown to be increased in case of a sudden stratospheric warming event. Summary WWOSC, Montréal, August 18th 2014 15 Domeisen et al., Seasonal Predictability over Europe arising from El Niño and Stratospheric Variability in the MPI-ESM Seasonal Prediction System, in review with J. Clim.

16. WWOSC, Montréal, August 18th 2014 16 Additional slides

17. WWOSC, Montréal, August 18th 2014 17 Anomaly Correlation Coefficient (ACC) (Dec/Jan/Feb/Mar) 500hPa geopotential height prediction skill for 1982 – 2010 average: MPI-ESM-LR model vs ERAinterim reanalysis persistence (Nov vs. Jan/Feb/Mar)

18. WWOSC, Montréal, August 18th 2014 18 European winter anomalies