Variability and changes in high impact hydrometeorological events

气候变化是一个不可避免的全球现象，将对加拿大产生重大影响。在加拿大的北极和亚北极地区，与海冰和积雪覆盖的区域变化相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方和东北部观察到的那样。这些变化也将影响当地和偏远南部地区的高影响天气事件，因为这些事件取决于这些区域反馈，这些反馈通过气象系统与向极的热量传输强烈相互作用。然后，需要在区域尺度上更好地预测不断变化的气象学（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部或区域尺度影响之间的耦合的理解。事实上，与单一变量模拟相关的许多关键过程都已被理解，但研究只是开始关注联合或组合变量的预测，特别是在涉及个别数量的极端或可变性时。在这种情况下，研究计划的总体目标是开发关于气候和天气极端和水文气象灾害的新知识，并提高社会管理与这些事件未来变化相关的风险的能力。拟议的科学方法将包括：1）配置新的区域气候模式运行，其中包含当前和未来时期的各种大气和海洋边界条件（来自再分析、全球气候模式以及新的高分辨率海面温度和海冰产品）; 2）开发新的诊断变量和多变量标准。拟议研究的独创性和创新性方面将是：1）提高我们目前对大规模大气环流变化与区域地表条件变化之间复杂联系的理解，以及它们对加拿大关键地区发生高影响风暴和极端事件的影响，2）根据对人类健康和自然或受干扰的生态系统的特殊影响，确定综合大气变量，3）制定新的和有针对性的区域尺度极端情况和水文气象灾害情景，在加拿大各地的适应战略中使用。拟议的研究将有助于培训HQP（3名硕士，2名博士和2名博士后研究员），以支持加拿大努力了解极端气候/天气或水文气象灾害将如何影响加拿大的人类，社会经济和自然系统。这也将有助于利益攸关方和公共机构发展预警系统，减少预期恶劣天气条件造成的伤害，从而有助于减少风险。

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.**