Titre : Candidate au doctorat

Affiliation: Université du Québec à Montréal (UQAM)

Sujet de recherche : Identification et évaluation des tempêtes à méso-échelle (MRCC6 à 12 km et 2,5 km.)

Superviseur : Philippe Gachon (UQAM)

Co-superviseurs : Alejandro Di Luca (UQAM)

Abstract:

Climate change is expected to increase temperatures and intensify extreme weather phenomena such as heavy rainfall, droughts, and flooding. In eastern Canada, several extreme events have already occurred in recent years, including severe storms and intense rainfall, from both synoptic and mesoscale weather events. Mesoscale Convective Systems (MCSs) play a major role among the systems responsible for heavy precipitation. This study investigates how climate change may modify the contribution of MCSs to mean and extreme precipitation over north-eastern North America. Two 11-year simulations performed with the CRCM6-GEM5 regional climate model for present and future climates are analyzed, both perform using horizontal grid spacing of 12 km and 2.5 km. Future climate conditions were simulated using the pseudo-global warming (PGW) framework, where a climate change perturbation derived from differences between the 1990–2014 and 2076–2100 periods under the SSP5-8.5 scenario are added to historical atmospheric conditions. An identification and tracking algorithm was used to examine MCSs characteristics and assess future changes. Preliminary results suggest that MCSs may become more intense under future conditions. However, the nature of these changes appears to be sensitive to the horizontal resolution of the model. In the 12-km simulations, the projected increase in MCS-related precipitation appears to be primarily due to an increase in the number of detected storms. As the PGW framework preserves historical large-scale circulation, this increase is likely reflecting thermodynamic effects in the precipitation and brightness temperature fields. In contrast, the changes in the 2.5-km simulations appear to be more strongly related to increases in storm intensity, likely reflecting the improved representation of convective processes at convection-permitting resolutions. The differences in the diurnal cycle and the contribution of MCSs to extreme precipitation are also examined.

Publications:
Alpizar M., Di Luca A., Gachon P. and Roberge F. (2026). Mesoscale Convective Systems in Northeastern North America: identification and evaluation with the convection-permitting version of the Canadian Regional Climate Model. Climate Dynamics, 64, 129 (2026). https://doi.org/10.1007/s00382-026-08102-6.