Physical insights on future European summer heatwaves
Margot Bador1, Laurent Terray1, Julien Boé1 , Samuel Somot2
1 CERFACS, Toulouse, France 2 CNRM, Meteo-France, Toulouse, France
Motivations • Large literature showing an increase of warm extreme events and
heatwaves over the 21st century in Europe (SREX Report, IPCC, 2012 ; Bador et al. 2015, Clim. Dyn.)
• Dynamical Downscaling to better describe the land-sea contrasts, orography and local processes
Methodology
Physical insights on future European summer heatwaves
Main Question • How can the regional modeling bring physical insights on the future
European summer heatwaves ?
Methodology 1. Select an intense summer heatwave from a climate model
2. Simulate this particular heatwave with the regional model
3. Perform several simulations with constant forcings
Margot Bador
The ALADIN model • Forcings: the CNRM-CM5 climate model (member
r1i1p1), surface and lateral boundary conditions
• EuroCordex version (ALADIN V5.3, Jacob et al. 2013), configuration and domain
• Spatial resolution: 12km
• Spectral nugding: no
Regional climate modeling
Physical insights on future European summer heatwaves Margot Bador
The 2075 heatwave in the CNRM-CM5 simulation • Heatwave Severity Index (Schoetter et al. 2014, Clim. Dyn.)
The most severe heatwave of the last 3 decades of the century :
intense, large spatial extension, very long duration (more than 30 days)
European future intense heatwaves
Physical insights on future European summer heatwaves Margot Bador
A strong control by the large scale circulation and the dynamical processes • Analog analysis based on the large scale
circulation (Deser et al. 2015, sub.)
• Construction of the temperatures due to dynamical processes only
The 2075 heatwave in the CNRM-CM5 simulation
Physical insights on future European summer heatwaves Margot Bador
Configuration of the experiments • Ensemble of 20 simulations
• Duration: from the 1st of June to the 31st of August
• Initialisation: restart from the EuroCordex simulation
• Forcings: the CNRM-CM5 simulation, RCP8.5
The 2075 heatwave in the ALADIN model
Physical insights on future European summer heatwaves Margot Bador
A large spread between the members
Physical insights on future European summer heatwaves Margot Bador
Do the soil-atmosphere interactions play a role in the inter-member spread ?
Physical insights on future European summer heatwaves Margot Bador
Conclusions
Future European intense heatwaves & Regional modeling
• Regional climate modeling can bring some physical insights on heatwaves
Large ensembles are needed: based on the 19 members simulating a similar large scale circulation to the CNRM-CM5 model, a spread up to 7°C exists during the heatwave, in average over Europe
• The soil-atmosphere interactions play a role in the inter-member spread
In the case of the 2075 heatwave, largely controlled by the dynamical processes, the differences in soil moisture content before the heatwave modulate the maximum temperatures up to 5°C during the heatwave, in average over Europe
Thank you for your attention ! [email protected]
Physical insights on future European summer heatwaves Margot Bador
APPENDIX
Selection of future intense heatwaves