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Summer 2003
Deviation from 1961-1990 mean
Based on ECMWFand ERA-40
Color: temperature anomaly
Contours: normalized by standard deviation
(Schär et al. 2004, Nature, 427, 332-336)
ºC
Temperature Anomaly June-August 2003
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Geopotential Height, 500 hPa
Deviation from 1961-1990 mean
Based on ECMWFand ERA-40
Color: height anomaly
Bold contours: anomalies normalized by standard deviation
Summer 2003
m
Mark Liniger
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Precipitation Anomaly
Deviation from 1961-1990 mean
Data: GPCC
Summer 2003
%
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Dried-up River Töss (Central Switzerland, August 28,2003)
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Estimation of Return Periods
extremelyrare
event
10 y10 y
1000 y1000 y
100 y100 y
mean
(Schär et al. 2004, Nature, 427, 332-336)
Swiss Temperature Series 1864-2003 (mean of 4 stations)
6 Changes in Mean
(Katz and Brown 1992, Folland et al. 2001, IPCC, 2001)
For extremes far away from mean, “variability is more important than mean”
cold warm cold warm
increase in the frequency of extreme warm conditions
increase in the frequency of extreme warm/cold conditions
Temperature
Frequency
versus Changes in Variability
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Summer Variability in Climate Change Scenarios
Atmospheric GCM(HadAM3, ~120 km)
Coupled GCM(HadCM3, ~300 km)
Greenhouse-Gas Scenario(IPCC SRES A2)
Regional Climate Model (RCM)(CHRM / ETH, 56 km)
(EU-Project PRUDENCE, NCCR Climate)
Time slice experimentsCTRL (1961-1990)SCEN (2071-2100)
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SCEN2071-2100
Simulated Summer Temperatures
CTRL1961-1990
Simulated:T= 16.1 ºC= 0.97 ºC
Observed:= 16.9 ºC= 0.94 ºC
Gridpoint near Zurich
T=4.6 ºC
/=100%
strongincrease
in variability
(Schär et al. 2004, Nature, 427, 332-336)
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[ºC] [%]
Change in Mean Temperature T Change in Variability /
Summer (JJA)
(Schär et al. 2004, Nature, 427, 332-336)
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Comparison of T and P anomalies
OBS: Swiss Series 1864-2003 SIM: CTRL and SCEN. OBS: 2003
Simulations suggest that by the end of the century every second summer is as warm or warmer (and as dry or dryer) than JJA2003
(with respect to 1961-1990)
(Schär et al. 2004, Nature, 427, 332-336)
