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1989-1994 Wageningen Universiteit/University of Reading
Bodem, Water en Atmosfeer – specialisatie meteorologie
1994-1998 KNMI/Universiteit Utrecht
Promotie fysische oceanografie
1999-2001 Columbia University (New York)
Postdoc Climate variability research
2002-2006 KNMI
Scientific Researcher
2006 – KNMI
Head of Division
2010 – Wageningen University
Hoogleraar Klimaatdynamica
Skill simplest weather and climate prediction
Autocorrelation at ‘lag n’ of averaged temperature at 2 meters (Hazeleger 2012; Thanks to G.J. van Oldenborgh)
Weather and climate models
upguut
2
Supercomputers
BULL KNMI, 58 Tflop (58 1012 operations/s, highest world wide 20 1015 = 20 Pflop)
IPAD-2 160 MFlop (160 106 operations/s)
Observations Modellen with all natural forcings (sun, volcanoes) Models with natural and anthropogenic forcings
IPCC, Figuur SPM 6
How good are seasonal predictions?
Correlation between observed temperature and predicted temperature
(2-4 months in advance; using 1981-2010 forecasts)
Climate in the next decade ( - 2021)
Skill in temperature good, but comparable to a statistical model
2016-2020 wrt 1971-2000
Smith et al 2012
Figure SPM.7
Global annual mean temperature change (wrt 1986 – 2005)
2.5 to 4.8°C
0.3 to 1.7°C
Long term temperature projections
Precipitation projections for Europe
summer winter
RCP 8.5, change in 2081-2100 wrt 1986 -2005 Hatching: 66% of all models; double hatching: 90%
IPCC Figuur 14.29
Can we predict weather and climate?
•Autocorrelation of observed 2-meter temperature, N-averaged, at lag N; lines) •Correlation skill from dynamical forecasts (ECMWF EPS, monthly forecasts, DEMETER and ENSEMBLES multimodel seasonal to decadal forecasts; symbols)
Hazeleger et al in prep
Predictability of weather and climate
‘Chaotic’ weather is predictable up to ~15 days
Statistics of weather is in some regions and some seasons
predictable months ahead
Predictable ‘slow’ components in the climate state: ocean, ice,
soil, atmospheric composition predictability decades ahead
External forcing of Earth system: greenhouse gases, land use,
solar radiation, volcanic ash unpredictable
Systematic error of models
‘what if’ climate scenarios: physical plausible and consistent
pictures of a future climate