European cold winter 2009-2010: How unusual in the instrumental record and how reproducible in the ARPEGE-Climat model?

International audienc

Heat waves analysis over France in present and future climate: Application of a new method on the EURO-CORDEX ensemble

AbstractCurrently, the analysis of heat waves and the representation of such events in a comprehensible and accessible way is a crucial challenge for climate services, in particular for delivering scientific support to policy makers. In order to fulfil this need, a new method for analysing the heat waves in France has been defined. Heat wave detection is based on the high quantiles of daily temperature distributions, and can be applied on any series of temperature. The heat waves are characterised by their duration, maximal temperature and global intensity. Their characteristics are calculated for historical and future climate based on the EURO-CORDEX regional multi-model ensemble, under two different Representative Concentration Pathway scenarios: RCP4.5 and RCP8.5. The historical simulations are evaluated against the SAFRAN reanalysis data. The EURO-CORDEX ensemble simulates heat waves which characteristics are consistent with the events detected from the SAFRAN thermal indicator between 1971 and 2005. Models are able to simulate waves as intense as the 2003 outstanding event. Under future climate conditions, whatever the considered scenario, the heat waves become more frequent and have higher mean duration and intensity. Moreover, heat waves could occur during a larger part of summer. The 2003 event corresponds to a typical event at the end of the century, and its duration and intensity are much lower than the strongest waves that could occur over the last 30years of the 21st century. However, the intensity of the evolution during the end of the century will strongly depend on climate policies

Diurnal temperature cycle deduced from extreme daily temperatures and impact over a surface reanalysis system

Due to the evolution of the observation network, hourly 2 m temperature analysis performed by reanalysis systems shows temporal inhomogeneities. The observation network gap is less present for extreme daily temperature observations. In order to reduce inhomogeneities and enable a climatological use of temperature analysis, information from extreme temperatures could be useful. In this study, the diurnal temperature cycle has been reconstructed for stations which only record extreme temperatures. These new "pseudo" hourly temperature observations are then provided to the analysis system. Two methods have been used to deduce hourly temperatures from extremes and compared to real observations. The results have shown that using those new pseudo-observations as an input for two different reanalysis systems enables reducing the bias in temperature analysis

Regional climate downscaling over Europe: perspectives from the EURO-CORDEX community

The European CORDEX (EURO-CORDEX) initiative is a large voluntary effort that seeks to advance regional climate and Earth system science in Europe. As part of the World Climate Research Programme (WCRP) - Coordinated Regional Downscaling Experiment (CORDEX), it shares the broader goals of providing a model evaluation and climate projection framework and improving communication with both the General Circulation Model (GCM) and climate data user communities. EURO-CORDEX oversees the design and coordination of ongoing ensembles of regional climate projections of unprecedented size and resolution (0.11° EUR-11 and 0.44° EUR-44 domains). Additionally, the inclusion of empirical-statistical downscaling allows investigation of much larger multi-model ensembles. These complementary approaches provide a foundation for scientific studies within the climate research community and others. The value of the EURO-CORDEX ensemble is shown via numerous peer-reviewed studies and its use in the development of climate services. Evaluations of the EUR-44 and EUR-11 ensembles also show the benefits of higher resolution. However, significant challenges remain. To further advance scientific understanding, two flagship pilot studies (FPS) were initiated. The first investigates local-regional phenomena at convection-permitting scales over central Europe and the Mediterranean in collaboration with the Med-CORDEX community. The second investigates the impacts of land cover changes on European climate across spatial and temporal scales. Over the coming years, the EURO-CORDEX community looks forward to closer collaboration with other communities, new advances, supporting international initiatives such as the IPCC reports, and continuing to provide the basis for research on regional climate impacts and adaptation in Europe.We acknowledge all participating institutions for their voluntary effort and contribution to EURO-CORDEX. We also thank the developers and maintainers of the ESGF-nodes who make it possible to store and distribute EURO-CORDEX data. S.S. acknowledges the support of NOTUR/NORSTORE projects NN9280K/NS9001K and the Research Council of Norway and its basic institute support of the strategic project on Climate Services. E.K. acknowledges the support of the Greek Research & Technology Network (GRNET) for provision of technical support and facilities (HPC-ARIS). L.S. and I.G. acknowledge the support of Croatian Science Foundation project CARE (2831) and Ministry of Environment and Energy project TF/HR/P3-M1-O1-0101 (www.prilagodba-klimi.hr). J. F. acknowledges support from the Spanish R+D Programme through grant INSIGNIA (CGL2016-79210-R), co-funded by ERDF/FEDER, and the Altamira Supercomputer at Instituto de Física de Cantabria (IFCA-CSIC), member of the Spanish Supercomputing Network. P.T. acknowledges support from the Belgian Science Policy (BELSPO) within the CORDEX.be (BR/143/A2) project, and the VSC (Flemish Supercomputer Center), funded by the Research Foundation - Flanders (FWO) and the Flemish Government – department EWI.M.A.G. acknowledges support from the Spanish R+D Programme through grants CGL2013-47261-R and CGL2017-89583-R, co-funded by the European Regional Development Fund. RF acknowledges support provided by ICHEC (Irish Centre for High End Computing) and the Irish Environmental Protection Agency. K.G. and S.K. gratefully acknowledge the computing time granted through JARA-HPC on the supercomputers JUROPA and JURECA at Forschungszentrum Jülich. M.B. and T.H. acknowledge support by The Ministry of Education, Youth and Sports from the Large Infrastructures for Research, Experimental Development and Innovations project “IT4Innovations National Supercomputing Center – LM2015070” and the INTER-EXCELLENCE program LTT17007, and support by Charles University from the PROGRES Q16 program. We acknowledge the approval and support of the two Flagship Pilot Studies (the FPS on Convective phenomena at high resolution over Europe and the Mediterranean and the FPS on Land Use and Climate Across Scales) by WRCP CORDEX. We thank Merja Tölle for providing simulation CCLM5-0-9-JLU as contribution to the CORDEX-FPS “Convective phenomena at high resolution over Europe and the Mediterranean”. D. M., M.P., and H.T. gratefully acknowledge the support received via the projects HighEnd:Extremes, SPIRIT, and reclip:convex, funded by the Austrian Climate Research Programme (ACRP) of the Klima- und Energiefonds (nos. B368608, B960272, and B769999, respectively), as well as the Jülich Supercomputing Centre (JSC) for compute time on JURECA through the grant JJSC39 and the Vienna Scientific Cluster (VSC) through the grants 70992 and 7119