A3. Storm track changes in future climate

Projected changes in weather storminess over Canada are expected to contribute to changes in weather extremes and hydro-meteorological hazards, through an interrelation of large-scale and regional-scale physical processes. The main objective of this project is to improve our understanding of the regional features of storm changes and the links between storm activities, including blocking events and weather extremes, and assessment of the effects of storminess changes on various timescales, from seasonal to decadal scales, for several regions across Canada. Storm tracks, frequency, intensity, duration and displacement of storms will be analysed using 1000 hPa vorticity maxima, following the approach of Sinclair (1997). Recent work by Mesquita et al. (2008) has shown that the mean sea level pressure (MSLP) field is often unable to identify the early stages of cyclogenesis, while vorticity field detects features much earlier than the MSLP field. This storm tracking has already been applied to identify the links between storm occurrences and the 1999-2005 drought episodes over the Canadian Prairies (e.g., Hanesiak et al., 2011), and to analyze the effects of storm events on storm surge and coastal processes in the Nunavik coastlines area. The storm tracking will be extended to analyse mesoscale systems in high-resolution simulations. The links between storm characteristics and extremes will be identified using the self-organizing map (SOM) algorithm (e.g. Cassano et al., 2006) to link the synoptic patterns and extreme events over land and coastal areas of Canada, as well as Singular Value Decomposition and Principal Component Analysis techniques. The storms and extremes analysis will be done using both reanalysis products (global: NCEP/NCAR, NCEP/DOE, ERA-Interim, MERA; regional: NARR), and available simulations of GCMs and RCMs for current and future periods, from NARCCAP, CORDEX, ESCER/UQAM, Ouranos and Canadian Centre for Climate modelling and analysis (CCCma). The extremes and hydro-meteorological hazards will encompass cold/hot waves, floods/droughts, and high wind speed events.

As storms can severely impact human and natural systems, this project will overall contribute to the improvement of alert systems developed at Environment Canada, and in the development of adaptation strategies at both national and provincial levels. One of the questions this project will try to answer is: What is the minimal model resolution required for an accurate simulation of storm intensity and tracks? This will contribute to reducing the uncertainties associated with key components of storminess, and extremes changes at the regional scale, i.e. at the scale relevant for impact studies and applications such as health, infrastructure, agriculture and hydrology.