Titre : Candidate au doctorat

Affiliation: Université du Québec à Montréal (UQAM)

Superviseur : Philippe Gachon (UQAM)

Co-superviseur : Alejandro Di Luca (UQAM)

Sujet de recherche : Identification et évaluation des systèmes convectifs à méso-échelle (MCS) dans le nord-est de l’Amérique du Nord et analyse de l’évolution future de leurs caractéristiques sous scénarios de changement climatique

Résumé :

Mesoscale convective systems (MCSs) are important contributors to extreme precipitation in northeastern North America and can pose significant risks through intense rainfall and strong winds. This study investigates the representation of MCSs and their associated precipitation in northeastern North America using observational, satellite, reanalysis, and model-based products, with a particular focus on the Canadian Regional Climate Model version 6 (CRCM6). MCSs are identified and characterized over the 2015–2022 period using a tracking algorithm applied to ERA5, IMERG, STAGE IV, MRMS, and CRCM6 simulations at 12 and 2.5 km horizontal resolution. The results show that lower-resolution products generally underestimate MCS occurrence and variability, whereas the 2.5-km convection-permitting configuration better reproduces key MCS characteristics, including occurrence, size, duration, precipitation intensity, diurnal cycle, and contribution to total and extreme precipitation.
Building on this evaluation, future changes in MCS activity are investigated using three CRCM6-GEM5 configurations that differ in horizontal resolution and convection treatment: 12 km with Kain–Fritsch convection, and 2.5 km with either Kain–Fritsch or explicit convection. Future conditions are represented using a pseudo-global warming approach based on SSP5-8.5 climate perturbations. The simulations indicate an overall intensification of MCS activity, with increases in frequency, size, precipitation intensity, and total precipitation volume, as well as an expansion of MCS occurrence into new areas. The relative contributions of frequency, area, and precipitation intensity to changes in total MCS precipitation volume differ among model configurations, highlighting the role of horizontal resolution in shaping the response of MCSs to climate change. In addition to precipitation changes, changes in maximum and extreme winds associated with MCSs will also be investigated under future climate conditions to assess potential changes in the wind-related hazards associated with these systems.

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. https://doi.org/10.1007/s00382-026-08102-6.  

Alpizar Tirzo, Milena, Alejandro Di Luca, and Philippe Gachon. 2026. “Mesoscale Convective Systems over Northeastern North America (MCS-NENA) Catalogue.” Borealis. https://doi.org/10.5683/SP4/WGF82T.

Alpizar M., Gachon P., Di Luca A. (2026). Future changes in Mesoscale Convective Systems and associated precipitation over Northeastern North America using a convection-permitting climate model. (Manuscript in progress)