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Extreme Precipitation from Extra-Tropical Cyclones: A Limited Area Model Climate Change Analysis

Extreme Precipitation from Extra-Tropical Cyclones: A Limited Area Model Climate Change Analysis. Adrian Champion, Kevin Hodges, Lennart Bengtsson NCEO National Centre for Earth Observation University of Reading. Adrian Champion a.j.champion@reading.ac.uk EGU, Vienna, 3 rd – 8 th April 2011.

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Extreme Precipitation from Extra-Tropical Cyclones: A Limited Area Model Climate Change Analysis

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  1. Extreme Precipitation from Extra-Tropical Cyclones:A Limited Area Model Climate Change Analysis Adrian Champion, Kevin Hodges, Lennart Bengtsson NCEO National Centre for Earth Observation University of Reading Adrian Champion a.j.champion@reading.ac.uk EGU, Vienna, 3rd – 8th April 2011

  2. Past Events – July 2007 (Reading) Adrian Champion a.j.champion@reading.ac.uk EGU, Vienna, 3rd – 8th April 2011

  3. Past Events – November 2009 (Cumbria) Adrian Champion a.j.champion@reading.ac.uk EGU, Vienna, 3rd – 8th April 2011

  4. Past Events – Winter 2009/2010 (UK) Adrian Champion a.j.champion@reading.ac.uk EGU, Vienna, 3rd – 8th April 2011

  5. Outline • Global Climate Model • Limited Area Model • Downscaling • Conclusions Adrian Champion a.j.champion@reading.ac.uk EGU, Vienna, 3rd – 8th April 2011

  6. Outline • Global Climate Model • Limited Area Model • Downscaling • Conclusions Adrian Champion a.j.champion@reading.ac.uk EGU, Vienna, 3rd – 8th April 2011

  7. Global Climate Model • ECHAM 5 GCM T319 & T213 • 40km (T319), 60km (T213) resolutions • TRACK software developed by Hodges (1995,1999) • 850hPa relative vorticity at T42 resolution • 2 day duration, travel 1000 km • 2 periods: • “20th Century”: 1980-2000 (T319)/1960-1990 (T213) • “21st Century”: 2080-2100/2070-2100 (T213) • 5° area around centre of storm • Extreme Value Theory used to investigate tails of distributions • Generalised Pareto Distribution (Peaks-over-Threshold) Champion, A.J., Hodges, K.I., Bengtsson, L.O., Keenlyside, N., 2011, Tellus A, submitted Adrian Champion a.j.champion@reading.ac.uk EGU, Vienna, 3rd – 8th April 2011

  8. Global Climate Model Adrian Champion a.j.champion@reading.ac.uk EGU, Vienna, 3rd – 8th April 2011

  9. Global Climate Model Adrian Champion a.j.champion@reading.ac.uk EGU, Vienna, 3rd – 8th April 2011

  10. Global Climate Model Adrian Champion a.j.champion@reading.ac.uk EGU, Vienna, 3rd – 8th April 2011

  11. Outline • Global Climate Model • Limited Area Model • Downscaling • Conclusions Adrian Champion a.j.champion@reading.ac.uk EGU, Vienna, 3rd – 8th April 2011

  12. Limited Area Model • UK Met Office’s Unified Model • vn6.1, non-hydrostatic • 12 km & 4 km resolutions • nested vs. makebc • 12W to 10E, 44N to 62N • ECMWF Operational Analysis initial conditions and boundary conditions • 4 lead times: 12, 24, 36 and 48 hours before peak precipitation, boundary conditions applied every 6 hours • Output every hour Adrian Champion a.j.champion@reading.ac.uk EGU, Vienna, 3rd – 8th April 2011

  13. Limited Area Model Adrian Champion a.j.champion@reading.ac.uk EGU, Vienna, 3rd – 8th April 2011

  14. Limited Area Model Adrian Champion a.j.champion@reading.ac.uk EGU, Vienna, 3rd – 8th April 2011

  15. Limited Area Model Adrian Champion a.j.champion@reading.ac.uk EGU, Vienna, 3rd – 8th April 2011

  16. Outline • Global Climate Model • Limited Area Model • Downscaling • Conclusions Adrian Champion a.j.champion@reading.ac.uk EGU, Vienna, 3rd – 8th April 2011

  17. Downscaling • Boundary conditions from ECHAM 5 T213 GCM • Events identified via TRACK • 6 events: 3 20th century climate, 3 21st century climate • cross the UK • travelling from South-West to North-East • UK Met Office’s Unified Model • vn6.1, non-hydrostatic • 12 km & 4 km resolutions • nested vs. makebc • 12W to 10E, 44N to 62N • 4 lead times: 12, 24, 36 and 48 hours before peak precipitation • ~100 km2 area around peak precipitation Adrian Champion a.j.champion@reading.ac.uk EGU, Vienna, 3rd – 8th April 2011

  18. Outline • Global Climate Model • Limited Area Model • Downscaling • Conclusions Adrian Champion a.j.champion@reading.ac.uk EGU, Vienna, 3rd – 8th April 2011

  19. Conclusions • GCM • resolution • DJF – more extreme events in 21C higher resolution only • JJA – more extreme events at higher resolution (both climates) • warmer climate • reduction in return periods for a given return level • LAM • 12 hour lead time produces most intense precipitation • nested/makebc: little difference at 12 hour lead time • raingauges: Met Office and 4km agree, EA don’t • Downscaling • no preliminary results www.nerc-essc.ac.uk/~ajc Adrian Champion a.j.champion@reading.ac.uk EGU, Vienna, 3rd – 8th April 2011

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