28 August 2006Steinhausen meeting Hamburg On the integration of weather and climate prediction...
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Transcript of 28 August 2006Steinhausen meeting Hamburg On the integration of weather and climate prediction...
28 August 2006 Steinhausen meetingHamburg
On the integration of weather and climate prediction
Lennart Bengtsson
28 August 2006 Steinhausen meetingHamburg
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
28 August 2006 Steinhausen meetingHamburg
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
28 August 2006 Steinhausen meetingHamburg
Improvements in NWP from Miyakoda (1972) to 2002. Courtesy ECMWF
How long to get to D+10 in winter?
2006 at day 9
28 August 2006 Steinhausen meetingHamburg
St. Petersburg ensemble prediction 10.1 2006
17th onward ca -30 C
28 August 2006 Steinhausen meetingHamburg
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
28 August 2006 Steinhausen meetingHamburg
ECHAM5simulated
ERA40determined
from analyses.
Köppen climate zones
28 August 2006 Steinhausen meetingHamburg
CoupledModelT63L31
Present climate
Future climate
28 August 2006 Steinhausen meetingHamburg
Observes and simulated QBONote the marked changes in wind direction at 10-20 hPa every 26-28
month
28 August 2006 Steinhausen meetingHamburg
20th Century (20C3M)
11/20 models have decadal signal
PIcntrl (Control Runs)10/20 models have decadal signal
IPCC AR4 Arctic Temperature Anomalies by AOGCMs
Courtesy, J Overland
28 August 2006 Steinhausen meetingHamburg
50-year trends>0.23 corresponds to 95% significance
T
PZ 850
Sea
ice
28 August 2006 Steinhausen meetingHamburg
Ten coldest European wintersmodel and “observations” ( Luterbacher, 2005)
Model Obs
Model global anomaly
Model height
500 hPa
28 August 2006 Steinhausen meetingHamburg
Pre-industrial temperatures in Europe (DJF)Model results
( smaller numbers in right column are observed values prior to 1950 covering ca 200 years
Mean T STD T Min Max
De Bilt +4.3 +2.0 1.4 1.8 -1.0 -3.1 +7.6 +5.3
Hamburg +1.4 1.8 -5.0 +5.6
Hohenpeissenb. -1.6 -1.4 1.8 1.9 -6.9 -6.1 +2.2 +2,8
Paris +3.8 + 3.3 1.4 1.6 -0.8 -1.6 +6.8 +6.6
Oxford +5.1(L) 1.2(L) +0.1 +8.0
Moscow -10.6 2.6 -19.7 -2.0
Uppsala -2.5 -4.0 1.7 2.3 -8.0 -9.9 +1.8 +1.4
St. Petersburg -8.5 -7.2 2.2 2.6 -15.7 -14.6 -1.5 -1.1
Warsaw -3.3 -2.8 2.2 2.3 -11.7 -9.2 +2.3 +1.4
Vienna -2.3 -0.5 1.9 1.8 - 8.5 -5.8 +2.1 +3.3
28 August 2006 Steinhausen meetingHamburg
T213 Cyclones (>1x103 sec-1), 1960-1990.
Simulation of hurricane trajectory during 30 years
ECHAM5 model at T213 resolution
Storms with 850 mb max. vorticity stronger than 10-3 s-1
Selected storm trajectory
28 August 2006 Steinhausen meetingHamburg
Intensity v Speed (T213)
28 August 2006 Steinhausen meetingHamburg
T213 Example Cyclone
Intensity and Speed MSLP
T63 Vertical Structure
28 August 2006 Steinhausen meetingHamburg
T213 Regional Speed Distribution.
28 August 2006 Steinhausen meetingHamburg
Effect of resolutionComparing ECHAM5 T213 with T63
Max. Speed (m/sec)
)
#/year
28 August 2006 Steinhausen meetingHamburg
Number of observed, ERA-40 analyzed and simulated by ECHAM5 (T159) hurricanes having a maximum wind
speed higher than 33ms-1
28 August 2006 Steinhausen meetingHamburg
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
28 August 2006 Steinhausen meetingHamburg
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
28 August 2006 Steinhausen meetingHamburg
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
28 August 2006 Steinhausen meetingHamburg
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
28 August 2006 Steinhausen meetingHamburg
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
28 August 2006 Steinhausen meetingHamburg
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
28 August 2006 Steinhausen meetingHamburg
END