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The role of increasing temperature variability in European summer heat waves Christoph Schär, Pier Luigi Vidale, Daniel Lüthi, Christoph Frei, Christian.

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Presentation on theme: "The role of increasing temperature variability in European summer heat waves Christoph Schär, Pier Luigi Vidale, Daniel Lüthi, Christoph Frei, Christian."— Presentation transcript:

1 The role of increasing temperature variability in European summer heat waves Christoph Schär, Pier Luigi Vidale, Daniel Lüthi, Christoph Frei, Christian Häberli, Mark A. Liniger & Christof Appenzeller

2 Literaturseminar 30. April, 2004 Overview Luterbach et al: European temperature trends and extremes since 1500 Summer 2003 data Schär et al: Increasing temperature variability in European heat waves

3 Literaturseminar 30. April, 2004 Luterbacher et al: European mean temperature since 1500 - warmest winter: 1989/90 T = +2.4°C - warmest decade: 1989-98 T = +1.2°C (second warmest 1733-42 T = +0.45°C) - linerar temperature trend for 20 th century: +0.08°C 0.07°C per dec. Winter

4 Literaturseminar 30. April, 2004 Luterbacher et al: European mean temperature since 1500 Summer - warmest summer: 2003 T = +2.0°C - warmest decade: 1994-03 T +1.2°C - conspicuous: warming trends of up to 0.7°C 0.20°C per decade can be observed 1731-57, 1923-47, and 1994- 2003

5 Literaturseminar 30. April, 2004 Luterbach et al: European mean temperature since 1500

6 Literaturseminar 30. April, 2004 Summer 2003 Data Warmest summer in the last 500 years in Europe (June, July, August) Sub tropic high pressure belt shifted north over southwestern Europe Warm air masses pushed north Unusually small amounts of precipitation during spring and summer months

7 Literaturseminar 30. April, 2004 Temperature anomaly summer 2003

8 Literaturseminar 30. April, 2004 Deviation from the avg temp (1876-2000) in Karlsruhe

9 Literaturseminar 30. April, 2004 Satellite views Satellitenbild, 8.8.2003, 12:09 UTC, NOAA 16, VIS Quelle: Inst. f. Meteorologie, FU Berlin Satellitenbild, 8.8.2003, 18:00 UTC, MET 7, IR Quelle: Fak. f. Ingenieurwissenschaften, Univ. Ulm

10 Literaturseminar 30. April, 2004 Summary: 2003 data

11 Literaturseminar 30. April, 2004 Summary: 2003 data Comparison to 1876-2000 avg

12 Literaturseminar 30. April, 2004 Schär et al: European temperature anomaly

13 Literaturseminar 30. April, 2004 Distribution of Swiss monthly temperatures 1864-2003

14 Literaturseminar 30. April, 2004 Monthly Temp anomalies (J-D) 1864-1923 & 1941-2000

15 Literaturseminar 30. April, 2004 Relative frequency change between the two periods

16 Literaturseminar 30. April, 2004 Estimation of return period Reference period = 1864-2000 return period several million years Accounting for warming: Reference period = 1990-2002 return period = 46000 yr. However: large uncertainty 90% confidence interval: = 9000 yr.

17 Literaturseminar 30. April, 2004 Modeling Regional climate model driven by two general circulation models at the lateral boundaries. Fairly high resolution Model control period (CRTL) 1961-90 shows good agreement with measured data for northern Switzerland: T(CRTL) = 16.1°C, SD = 0.96°C T(Meas) = 16.9°C, SD = 0.94°C

18 Literaturseminar 30. April, 2004 Modeling: Future scenario (SCEN) 2071-2100 summer Statistical temperature distributions resulting from the RCM driven by a greenhouse-gas scenario

19 Literaturseminar 30. April, 2004 Temperature change and variability according to SCEN

20 Literaturseminar 30. April, 2004 Temperature and precipitation anomalies in n. Switzerland Measurement data 1864-2003CTRL & SCEN data

21 Literaturseminar 30. April, 2004 Schär et al: Conclusion A shift of the statistical temperature distribution towards warmer temperatures fails to explain summer 2003 temperatures Proposal: An increase in variability as well as mean temperature may account for summer 2003 conditions RCM simulations seem to verify this hypothesis


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