Global climate modelling
Past and future climate change
Statistical downscaling for precipitation
Current / Recent Research
PLEIADES: Statistical downscaling for precipitation extremes
Extreme precipitation events constitute major natural hazards. Reliable estimates of precipitation changes are required at local scales where impacts are most keenly felt. However, the limited spatial resolution and the systematic errors of precipitation simulated in General Circulation Models (GCMs) make direct estimates of future daily precipitation from GCMs unrealistic. As part of the international research project PLEIADES (funded by the Volkswagen Foundation) we aim to develop a correction approach based on Model Output Statistics (MOS) to downscale GCM-simulated daily precipitation distributions. Skilful downscaling models will be applied to GCM simulations for the 21st century in order to produce more meaningful projections of local- and regional-scale precipitation, including extreme events.
Collaborators: Dr Martin Widmann, Dr Geraldine Wong (GEOMAR, Kiel), Dr Douglas Maraun (GEOMAR, Kiel), Dr Mathieu Vrac (LSCE-IPSL, Gif-sur-Yvette).
VALUE: Validating and Integrating Downscaling Methods for Climate Change Research (EU COST Action ES1102)
Understanding the skill of methods used to downscale future scenarios is a crucial component of climate change science. However, many aspects of downscaling methods, including the representation of extreme events and spatial coherence, have not been systematically validated. The COST Action VALUE (2011-2015) provides a research network across Europe and facilitates the interaction of various research communities with stakeholders. Over the course of four years, VALUE will deliver an assessment of end-user needs, a benchmark dataset and a comprehensive validation of a suite of downscaling methods. Jonathan is a member Working Group 4, which specifically aims to review, validate and improve methods to downscale extremes.
Validation of GCM-simulated precipitation
The reliability of General Circulation Model (GCM) projections of future precipitation is usually based simply on the degree of consensus amongst multiple GCMs. More meaningful projections should ideally consider the errors and biases associated with each GCM. We conduct ‘nudged’ simulations of the ECHAM5 GCM on the University of Birmingham’s BlueBEAR Linux cluster in which the circulation and temperature fields are forced towards corresponding quasi-observations. In forcing the large-scale climatic state into temporal phase with the observed record, it is possible to compare the sequence of events in observed and simulated precipitation, and thus identify regions where performance in representing temporal variability is strong.
Collaborators: Dr Martin Widmann, Dr Sebastian Rast (Max Planck Institute for Meteorology, Hamburg), David Grawe (University of Hamburg).
Climate reconstruction and predictability in Ethiopia
Speleothems have been shown to provide high resolution archives of climate information. Previous work has demonstrated that speleothem proxy reconstructions of precipitation for the Ethiopian highlands are able to capture signals of annual and seasonal climate variability. As part of this NERC-funded project, we aim to assess the plausibility of our speleothem reconstruction by comparing its consistency with General Circulation Model (GCM) simulations.
Additionally, there is much to be understood about the links between African climate and large-scale atmospheric and oceanic variations. We aim to identify the large-scale climate anomalies that control the Ethiopian precipitation. By statistically linking long-term observational records with gridded sea-surface temperature and reanalysis fields, we aim to establish the predictability of the spring and summer precipitation regimes in Ethiopia.
Collaborators: Dr Martin Widmann, Prof. Ian Fairchild, Dr Catherine Jex (University of New South Wales), Prof. Andy Baker (University of New South Wales).
Eden, J.M., Widmann, M., Wong, G., Maraun, D., Vrac, M. and Kent, T. MOS downscaling of RCM- and GCM-simulated daily precipitation (in preparation).
Eden, J.M. and Widmann, M. Downscaling of GCM-simulated precipitation using Model Output Statistics, Journal of Climate (submitted).
Eden, J.M., Widmann, M. and Evans, G.R. Pacific SST influence on spring precipitation in Addis Ababa, Ethiopia, International Journal of Climatology (in press).
Eden, J.M., Widmann, M., Grawe, D. and Rast, S. 2012. Skill, correction and downscaling of GCM-simulated precipitation, Journal of Climate, 25 (11), 3970-3984.
Jex, C.N., Baker, A., Eden, J.M., Eastwood, W.J., Fairchild, I.J., Leng, M.J., Thomas, L. and Sloane, H.J. 2011. A 500 year speleothem derived reconstruction of late autumn-winter precipitation, North East Turkey, Quaternary Research, 75 (3), 399-405.
Selected conference presentations
Eden, J.M., Widmann, M., Wong, G., Maraun, D., Vrac, M. and Kent, T. MOS downscaling of RCM- and GCM-simulated daily precipitation, EGU General Assembly, Vienna, Austria, 07-12 April 2013.
Eden, J.M., Widmann, M., Wong, G., Maraun, D., Vrac, M. and Kent, T. MOS correction of GCM- and RCM-simulated daily precipitation, International Symposium on Extreme Events: Modelling, Analysis and Prediction, Hanover, Germany, 13-15 February 2013.
Eden, J.M. and Widmann, M. Downscaling precipitation projections using event-wise MOS correction of GCM simulations, International VALUE Conference on "End User Needs for Regional Climate Change Simulations", Kiel, Germany, 07-09 March 2012.
Eden, J.M. and Widmann, M. Statistical downscaling of future changes in European precipitation using Model Output Statistics, AGU Fall Meeting, San Francisco, USA, 13-17 December 2010.
Eden, J.M. and Widmann, M. Estimating future changes in daily precipitation distribution from GCM simulations, 11th International Meeting on Statistical Climatology, Edinburgh, UK, 12-16 July 2010.
Eden, J.M. and Widmann, M. Statistical downscaling of GCM-simulated precipitation using Model Output Statistics. EGU General Assembly, Vienna, Austria, 02-07 May 2010.
Eden, J.M., Widmann, M., Grawe, D. and Rast, S. Validating simulated precipitation in GCMs. 4th International Verification Methods Workshop, Helsinki, Finland, 4-10 June 2009.