WINTER PRECIPITATION TYPES AND THEIR OCCURRENCE

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Precipitation affects us all and this research focuses on one of its aspects, freezing rain which is often associated with ice pellets. The icing from this precipitation can lead to catastrophic consequences, such as during December 2013 in Toronto. We still have many uncertainties about such precipitation ranging from gaps in understanding its fundamental features and driving mechanisms to our ability to monitor it and to anticipate its future occurrence. The objective of this component of my overall research program is to better understand freezing rain/ice pellets and to apply this insight through an examination of four sub-objectives. The research will be the focus for 1 PhD student, 3 MSc students, and 5 undergraduate students. ******The features of the precipitation will be studied using hands on' observations and model simulations. Special attention will be paid to documenting ice pellet features at the University of Manitoba (Winnipeg) and Churchill, Manitoba (western Canada's freezing precipitation capital) and the formation of aggregated ice pellets will be modelled to assess their role in reducing freezing rain through collection of supercooled drops aloft. ******Storm conditions leading to freezing rain/ice pellets in three locations will be contrasted and synthesized using observational and model information. Events occurring over Winnipeg and Churchill will be investigated collectively with major freezing rain events affecting Toronto (including the December 2013 event). As well, the trajectories of falling, initial ice particles will be examined to determine what orographic and frontal circulations and temperature fields allow freezing rain to be produced without a vertical temperature profile having an above-freezing layer.******Trends and variability in the occurrence of the freezing rain/ice pellets will be examined using operational surface and sounding information but also incorporating insight on precipitation formation mechanisms. A key issue is linking such issues with the changing climate and this will consider the tendency of extratropical systems to be moving slower over the Canadian Prairies and the impact of nearby lake/ocean ice cover variations. ******Insight from the preceding three activities will be applied to monitoring at the surface and through remote sensing, to the prediction of hazardous icing conditions, and to projections of future conditions in our changing climate. ******Overall, the freezing rain/ice pellet focus of this component of my research program enhances our understanding of the formation, detection and occurrence of this precipitation. This knowledge contributes to improved monitoring and prediction that reduce the likelihood of disasters. Students trained through this research will have expertise from precipitation science to its future occurrence so this next generation will be able to tackle the many future precipitation-related challenges.**