Grant: Canada Research Chairs

The frequency and intensity of extreme weather events may increase over the next few decades due to climate change. During the cold season, these high-impact events usually involve temperatures near 0°C that can lead to hazardous precipitation types such as ice pellets, freezing rain and wet snow. The occurrence of such conditions will likely change in warmer conditions but given the importance of temperatures at near 0°C, further research is needed to better anticipate those changes. It is essential to better understand the physical processes associated with precipitation, particularly mixed phase precipitation, to develop reliable methods to predict and measure its occurrence. Given these challenges, this research program will fill gaps in the field of extreme winter weather events. The overall goal is to improve our understanding of the factors responsible for extreme winter weather events, such as the type, intensity, and duration of precipitation to better anticipate their evolution with climate change. This will be addressed through 3 research themes: (1) the identification of the key atmospheric conditions and factors leading to high-impact winter events; (2) the investigation of the fine-scale characteristics of hazardous precipitation types, including precipitation phase transitions; and (3) the study of the changes in storm severity in a changing climate. To do so, multiple research tools will be used. These are targeted field experiments, automatic measurements, manual observations, and atmospheric modelling tools. Threshold atmospheric conditions triggering precipitation during the storms will be investigated. State-of-the-art measurements of winter precipitation types will also be conducted to improve their detection and to better understand the processes leading to their formation. These points are crucial to improve the representation of hazardous precipitation types cloud and precipitation microphysics scheme used in atmospheric, including very-high resolution convection-permitting climate models. Current models use a horizontal resolution in the order of kilometers, which allows the investigation of fine-scale mechanisms associated with cloud and precipitation formation. Overall, this research program will address the fundamentals of the key factors affecting the severity of storms, which are essential to anticipate the occurrence of extreme winter events in a context of ongoing and future climate changes.