Fundamentals of winter precipitation: theory and measurements

冬季降水的基础知识：理论和测量

• 批准号: RGPIN-2019-06654
• 负责人: Thériault, Julie
• 金额: $ 2.62万
• 依托单位: Université du Québec à Montréal
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=686640
• 关键词: Fundamentals; winter; precipitation; theory; measurements

Near-freezing temperatures and a mixture of precipitation types such as snow, freezing rain and wet snow are often linked to cold season high-impact events. One example is the 1998 Ice Storm where up to 100 mm accumulated at the surface. The difficulty in both their simulation and their detection arises because the precipitation types reaching the surface depend on the atmospheric conditions and they can be formed of liquid, solid or a mixture. The long-term objective is to improve the fundamental representation of winter precipitation type formation into models, including their detailed characteristics, as well as their interactions with other particles and the environment. This research program will fund 11 highly qualified personals (HQPs). They will use a combination of numerical experiments using high-resolution atmospheric models, field measurements and theoretical approaches to address the following three key issues. First, the key formation processes will be studied theoretically and by using well-observed storms. In particular, the processes leading to the freezing of falling precipitation particles will be investigated to differentiate between ice pellets and freezing rain. Second, the detailed characteristics of precipitation particles in various regions of Canada will be assessed using information on the particles' sizes and fall speeds measured in the field by an optical detector of precipitation particles. Long-term datasets will be analysed to compare the characteristic of the particles in different climatic regions of Canada (ex: Alberta and southern Québec). This information will be used to determine the performance of automatic snow gauges. Third, the precipitation type characteristics in the context of climate change over southern Québec will be evaluated. Targeted high-resolution climate simulations, which include the formation of freezing rain, will be conducted. Threshold values of the precipitation particle characteristics such as their sizes and falls peed will be assessed and linked to the storms atmospheric conditions. Overall, the issue of winter precipitation is of major importance to Canada where winter storms are often experienced across the country. Precipitation is one of the most important factors as the specific type of precipitation and intensity can have catastrophic consequences on the environment and on infrastructures. Each weather event contributes to the regional climatology, hence, further investigation on winter storms and associated precipitation will be a key step to bridge the gap with climate studies and better anticipate their changes in the future. The outcome of this research program will serve to a broad community such as hydrology, policy makers for risk assessment, and the private sector, in particular electrical utilities, to develop mitigation plan.

接近冰点的温度和雪、冻雨和湿雪等降水类型的混合往往与寒冷季节的高影响事件有关。其中一个例子是1998年的冰风暴，在表面积累了100毫米。由于到达地表的降水类型取决于大气条件，它们可以由液体、固体或混合物形成，因此在模拟和探测方面都存在困难。长期目标是改进冬季降水类型形成模型的基本表示，包括其详细特征，以及它们与其他粒子和环境的相互作用。该研究计划将资助11名高素质人员（HQP）。他们将结合使用高分辨率大气模型的数值实验、实地测量和理论方法来解决以下三个关键问题。首先，将从理论上和通过使用观测良好的风暴来研究关键的形成过程。特别是，将研究导致降水粒子冻结的过程，以区分冰球和冻雨。第二，将利用光学降水粒子探测器实地测量的粒子大小和下落速度的信息，评估加拿大各地区降水粒子的详细特征。将对长期数据集进行分析，以比较加拿大不同气候区域（例如：阿尔伯塔和魁北克南部）的颗粒特征。这些信息将用于确定自动雪量计的性能。第三，魁北克省南部气候变化背景下的降水类型特征将进行评估。将进行有针对性的高分辨率气候模拟，包括冻雨的形成。将评估降水粒子特征的阈值，如它们的大小和福尔斯速度，并将其与风暴的大气条件联系起来。总体而言，冬季降水问题对加拿大至关重要，全国各地经常经历冬季风暴。降水是最重要的因素之一，因为特定类型的降水和强度可能对环境和基础设施造成灾难性后果。每一次天气事件都对区域气候学有贡献，因此，对冬季风暴和相关降水的进一步研究将是弥合与气候研究的差距并更好地预测未来变化的关键一步。这项研究计划的成果将服务于广泛的社会，如水文，风险评估的决策者，和私营部门，特别是电力公司，制定缓解计划。