Variability and changes in high impact hydrometeorological events

气候变化是一个不可避免的全球现象，将强烈影响加拿大。在加拿大的北极和亚北极地区，与海冰和积雪的区域变化有关的反馈将放大预期的地表变暖，正如过去三十年在加拿大北部和东北部观测到的那样。这些变化还将影响当地和南部偏远地区的高影响天气事件，因为这些天气事件依赖于这些通过气象系统与向极地热输送强烈相互作用的区域反馈。然后，需要在区域尺度上更好地预测变化的气象（基于天气事件的发生、持续时间和强度），以及联合气候变量的相关变化，以提高我们对与大气环流驱动机制相互作用的局地或区域尺度影响之间耦合的理解。事实上，与单变量模拟有关的许多关键过程已被了解，但研究才刚刚开始集中于开发联合或组合变量的预测，特别是在涉及个别数量的极端或变异性时。

Climate change is an unavoidable global phenomenon that will strongly affect Canada. Over Arctic and subarctic regions of Canada, feedbacks associated with regional changes in sea-ice and snow cover will amplify anticipated surface warming, as observed over the last three decades in northern and northeastern Canada. These changes will also affect high impact weather events, locally and over remote southern regions, as those depend on these regional feedbacks that strongly interact with poleward heat transports through meteorological systems. Then, better projections of the changing meteorology (based on occurrence, duration and intensity of weather events) at regional scales are needed, as well as pertinent changes in joint climatic variables to improve our understanding on the coupling between local or regional-scale influences that interact with atmospheric circulation driven mechanisms. In fact, many of the key processes relevant to the simulation of single variables are understood, but studies are only starting to focus on developing projections of joint or combined variables, especially when extremes or variability in the individual quantities are concerned. In this context, the overall objective of the research program is to develop new knowledge on climate and weather extremes and hydro-meteorological hazards, and to improve society's ability to manage risks associated with future changes of these events. The proposed scientific approach will consist to 1) configure new Regional Climate Models' runs with various atmospheric and oceanic boundary conditions (from reanalysis, global climate models, and new sea surface temperatures and sea-ice products available at high resolution) over current and future periods, and 2) develop new diagnostic variables and multivariate criteria. The originality and innovative aspects of the proposed research will be to 1) improve our current understanding on the complex links between the large-scale atmospheric circulation variability and the changes in regional surface conditions and their effects on the occurrence of high impact storms and of extreme events over key Canadian areas, 2) define combined atmospheric variables based on their particular impacts on human health and natural or perturbed ecosystems, and 3) develop new and oriented regional scale scenarios of extremes and hydro-meteorological hazards, for their uses in adaptation strategies across Canada. The proposed research will contribute to train HQPs (3 Msc, 2 PhDs and 2 Post-Doctoral fellows) in order to support Canada's effort to understand how climate/weather extremes or hydro-meteorological hazards will affect Canada's human, socio-economic and natural systems. This will also help stakeholders and public institutions to develop early warning systems that could reduce injuries due to anticipated severe weather conditions, thus contributing to risk reduction.