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 EGU, Vienna, 3 rd – 8 th April 2011

Past Events – July 2007 (Reading) Adrian Champion EGU, Vienna, 3 rd – 8 th April 2011

Past Events – November 2009 (Cumbria) Adrian Champion EGU, Vienna, 3 rd – 8 th April 2011

Past Events – Winter 2009/2010 (UK) Adrian Champion EGU, Vienna, 3 rd – 8 th April 2011

Outline Global Climate Model Limited Area Model Downscaling Conclusions Adrian Champion EGU, Vienna, 3 rd – 8 th April 2011

Outline Global Climate Model Limited Area Model Downscaling Conclusions Adrian Champion EGU, Vienna, 3 rd – 8 th April 2011

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: – “20 th Century”: (T319)/ (T213) – “21 st Century”: / (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 EGU, Vienna, 3 rd – 8 th April 2011

Global Climate Model Adrian Champion EGU, Vienna, 3 rd – 8 th April 2011

Global Climate Model Adrian Champion EGU, Vienna, 3 rd – 8 th April 2011

Global Climate Model Adrian Champion EGU, Vienna, 3 rd – 8 th April 2011

Outline Global Climate Model Limited Area Model Downscaling Conclusions Adrian Champion EGU, Vienna, 3 rd – 8 th April 2011

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 EGU, Vienna, 3 rd – 8 th April 2011

Limited Area Model Adrian Champion EGU, Vienna, 3 rd – 8 th April 2011

Limited Area Model Adrian Champion EGU, Vienna, 3 rd – 8 th April 2011

Limited Area Model Adrian Champion EGU, Vienna, 3 rd – 8 th April 2011

Outline Global Climate Model Limited Area Model Downscaling Conclusions Adrian Champion EGU, Vienna, 3 rd – 8 th April 2011

Downscaling Boundary conditions from ECHAM 5 T213 GCM Events identified via TRACK – 6 events: 3 20 th century climate, 3 21 st 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 km 2 area around peak precipitation Adrian Champion EGU, Vienna, 3 rd – 8 th April 2011

Outline Global Climate Model Limited Area Model Downscaling Conclusions Adrian Champion EGU, Vienna, 3 rd – 8 th April 2011

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 Adrian Champion EGU, Vienna, 3 rd – 8 th April 2011