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The European flooding of summer 2002 and its global connections Mike Blackburn, Brian Hoskins, Pete Inness, Julia Slingo Centre for Global Atmospheric.

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Presentation on theme: "The European flooding of summer 2002 and its global connections Mike Blackburn, Brian Hoskins, Pete Inness, Julia Slingo Centre for Global Atmospheric."— Presentation transcript:

1 The European flooding of summer 2002 and its global connections Mike Blackburn, Brian Hoskins, Pete Inness, Julia Slingo Centre for Global Atmospheric Modelling, The University of Reading, UK

2 Flooding in Central Europe

3 Central European rivers

4 European Precipitation (percent of normal) JJA 2002August 2002

5 July Drought in India

6 Indian Precipitation: summer totals Source: K. Rupa Kumar & J.V. RevadekarMonsoon Online: Rainfall for the period 1 June to 30 Sept., 2002

7 All-India Precipitation: seasonal evolution Source: K. Rupa Kumar & J.V. Revadekar Daily total (mm)Daily accumulation

8 Start of El Niño in the Pacific Niño 3.4 Index for JJA Niño 3.4 area: 170W-120W, 5N-5S

9 Theoretical? Historical correlation of interannual variability? Could there be a link between these events?

10 Monsoon / Mediterranean link Idealised modelling: Rodwell & Hoskins (1996) Mid-level descent ω(477hPa)Pressure, wind (325K) Full model: global heating and orography Idealised monsoon heating (25°N), no orography Idealised monsoon heating (10°N), no orography Obs. JJA ω(477hPa)

11 Rodwell & Hoskins (1996) continued… Seasonal evolution of Mediterranean descent, 22:42°N, 8-37°E 477hPa ω from ECMWF analyses, 1994

12 All-India rainfall index, NCEP/NCAR Reanalysis ω at 500hPa, global Interannual variability is correlated Indian monsoon rainfall and Southern European Descent (JJA)

13 NCEP/NCAR Reanalysis ω 35:45°N 0:30°E Correlation coefficient 0.39 ( ) Higher correlation by crudely including a Pacific SST index But no correlation of AIR with European rainfall Indian monsoon rainfall and Southern European Descent (July)

14 Correlations between:. N34 AIR w500 CRU N AIR w500 – CRU July Niño 3.4 SST All India rainfall w500 S. Europe [35-45N,0-30E] CRU Precipitation S.Europe - All time-series detrended - All-India rainfall and S. European descent July (not detrended)

15 ω 500hPa : Dry monsoon composites for July NCEP/NCAR reanalysis data captures the local Indian ω anomaly Ascent anomaly over southern Europe El Niño signal in Pacific (not shown) All-India rainfall : 3 driest months July 1972, 1987, 2002 All-India rainfall : 7 driest months (exceeding 1 std-devn)

16 CRU land precipitation 35:45°N 0:30°E NCEP/NCAR Reanalysis height European Blocking pattern 200hPa Geopotential Height pattern correlating with Southern European Rainfall (JJA)

17 CRU land precipitation 35:45°N 0:30°E NCEP/NCAR Reanalysis msl pressure European Blocking pattern Sea level Pressure pattern correlating with Southern European Rainfall (JJA)

18 (negative) Indian Rainfall (JJA) Niño 3.4 SST (JJA) 200hPa Geopotential Height correlations with indices of....

19 What happened during Summer 2002?

20 JJA Climatology 500hPa Omega 200hPa Height 500hPa Omega JJA 2002

21 2002 monthly anomalies - 200hPa Height September JulyJune August

22 NCEP/NCAR Reanalysis data Streamfunction anomaly at σ = July/August 2002 (m 2 s -1)

23 Downstream Development Meridional wind anomaly 250hPa, 45-60N JA July – 26 Aug.

24 Downstream Development 1st 3rd 5th 7th 9th 11th 250hPa Streamfunction ECMWF analyses, 12UTC 1-11 August 2002 NWesterly flow over UK into the Mediterranean, 9-11 th Aug. A weather system followed this track and developed over Italy Then tracked NE bringing 150mm rain to much of central Europe

25 Animation for early August: Downstream Development ECMWF analyses

26 Conclusions Multiple influences on S. European summer variability Theoretical and weak historical link to Indian monsoon Importance of European blocking Experimentation needed to determine causality for a single event/season: idealised model with prescribed tropical forcing GCM with realistic variability & teleconnections? Extreme events: large signals stochastic component of precipitation


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