On the integration of weather and climate prediction

1. On the integration of weather and climate prediction Lennart Bengtsson Steinhausen meeting Hamburg

2. On the integration of weather and climate prediction • What has been achieved in weather and climate modeling? • What are probably now the most pressing issues? • What is needed to achieve this? • A strategy for climate prediction in Europe Steinhausen meeting Hamburg

3. What has been achieved in weather modeling? • Useful global prediction of synoptic scale weather for more than a week ahead • Successful introduction of ensemble prediction • Modest achievements in seasonal prediction of weather anomalies Steinhausen meeting Hamburg

4. Improvements in NWP from Miyakoda (1972) to 2002. Courtesy ECMWF 2006 at day 9 How long to get to D+10 in winter? Steinhausen meeting Hamburg

5. St. Petersburg ensemble prediction 10.1 2006 17th onward ca -30 C Steinhausen meeting Hamburg

6. What has been achieved in climate modeling? • Realistic simulation of the general circulation of the atmosphere including many extreme features • Major progress in simulating key aspects of the ocean circulation • Progress in incorporating the interactions with the biosphere • Demonstrating with relatively high probability that climate variations during the 20th century have been dominated by natural climate processes • Demonstrating ( with high probability) that the climate trend of the 20th century cannot be explained without anthropogenic forcing • Simulations of the climate of the 21st century with increasingly realistic models Steinhausen meeting Hamburg

7. Köppen climate zones ECHAM5 simulated ERA40 determined from analyses. Steinhausen meeting Hamburg

8. Present climate Coupled Model T63L31 Future climate Steinhausen meeting Hamburg

9. Observes and simulated QBONote the marked changes in wind direction at 10-20 hPa every 26-28 month Steinhausen meeting Hamburg

10. IPCC AR4 Arctic Temperature Anomalies by AOGCMs 20th Century (20C3M) 11/20 models have decadal signal Courtesy, J Overland PIcntrl (Control Runs) 10/20 models have decadal signal Steinhausen meeting Hamburg

11. 50-year trends>0.23 corresponds to 95% significance T Sea ice Z 850 P Steinhausen meeting Hamburg

12. Ten coldest European wintersmodel and “observations” ( Luterbacher, 2005) Model Obs Model global anomaly Model height 500 hPa Steinhausen meeting Hamburg

13. Pre-industrial temperatures in Europe (DJF)Model results ( smaller numbers in right column are observed values prior to 1950 covering ca 200 years Steinhausen meeting Hamburg

14. Simulation of hurricane trajectory during 30 years ECHAM5 model at T213 resolution Storms with 850 mb max. vorticity stronger than 10-3 s-1 T213 Cyclones (>1x103 sec-1), 1960-1990. Selected storm trajectory Steinhausen meeting Hamburg

15. Intensity v Speed (T213) Steinhausen meeting Hamburg

16. T213 Example Cyclone Intensity and Speed MSLP T63 Vertical Structure Steinhausen meeting Hamburg

17. T213 Regional Speed Distribution. Steinhausen meeting Hamburg

18. Effect of resolutionComparing ECHAM5 T213 with T63 #/year ) Max. Speed (m/sec) Steinhausen meeting Hamburg

19. Number of observed, ERA-40 analyzed and simulated by ECHAM5 (T159) hurricanes having a maximum wind speed higher than 33ms-1 Steinhausen meeting Hamburg

20. What are probably now the most pressing issues? • To better clarify what is predictable and not predictable • To better clarify the climate feedback processes • To determine the regional climate change and its separation from natural climate variability • To estimate risks of extreme events on different time scales Steinhausen meeting Hamburg

21. Climate precdictability • This will require models resolving high amplitude features • This will require ensemble prediction to separate signal from noise • This will require more advanced modeling and significantly increased computer resources Steinhausen meeting Hamburg

22. Climate feedback processes • The handling of clouds in models is the single most important issue • This is likely to require higher resolutions as clouds are associated with weather systems at different scales • This will require detailed validation and experimentation using best possible observed data. It will best be used to use the models in a forecasting mode Steinhausen meeting Hamburg

23. Predicting risks of extreme events • Significant harm to society is related to high frequency synoptic events ( hurricanes, extra-tropical storms) and to longer lasting anomalies such as heat waves and droughts • Longer term risks include flooding in coastal areas related to sea level rise • Global type risks (probably longer term), melting of Greenland ice, West Antarctica, major changes in ocean circulation Steinhausen meeting Hamburg

24. A strategy for climate prediction in Europe • There is a need for regular climate prediction to support environmental policies • Europe has in climate and environmental policy more or less common interests and objectives • In order to keep and enhance credibility in modeling this could best be achieved by a European agency with long term commitments of an operational nature • Required resources in man power and computers can hardly be found on a national level in the longer term Steinhausen meeting Hamburg

25. A strategy for climate prediction in Europe • A joint European climate modeling and prediction initiative could be set up as an integrated part of ECMWF but with a research program organized in a different way • Most of the research could best be done within national research units as now but with the difference that the work is done within a common framework • A changed convention for ECMWF is presently being approved by the national governments and is expected to come into force in 2007 • The new ECMWF convention will make it possible to set up a climate prediction program Steinhausen meeting Hamburg

26. END Steinhausen meeting Hamburg