Does Northern Hemisphere Snow Cover Influence Mid-latitude Cyclone Trajectories? Weather System Implications for a Changing Climate

冬季风暴对北美的社会和经济产生了重大影响。50多年来，气象预报员已经注意到，先前存在的积雪覆盖的南部范围的位置似乎会影响随后风暴的路径和强度。然而，无论是有效性，也没有这种预测经验法则的物理机制进行了严格的调查。了解这些风暴如何以及在哪里形成，无论是现在还是将来，与雪线的关系，需要大尺度气候动力学理论和模型的进步。该项目将对北美洲中部/东部更广泛的积雪和气旋观测进行全面的统计分析，并利用数值模型模拟评估有关基本机制的假设。这些研究结果将用于解决这一过程如何在气候模型中体现的问题，并确定中纬度雪线过去和预测的后退和前进所引起的中纬度风暴轨迹的变化，更好地了解地球系统的特征，特别是积雪如何在天气系统中表现出来，将导致天气和气候预报的改进，并有利于天气灾害的风险管理。关于积雪和中纬度风暴轨迹的新数据库将免费向公众提供。该项目支持一名博士生和两名本科生，他们将在天气-气候界面的新兴领域接受培训。

Winter storms have significant societal and economic impacts in North America. For over 50 years, forecasters have noted that the location of the southern extent of pre-existing snow cover appears to affect the tracks and intensity of storms that follow afterwards. However, neither the validity nor the physical mechanisms underlying this forecasting rule-of-thumb have been rigorously investigated. Understanding how and where these storms form, both currently and in the future, in relation to the snow line, requires advances in theories and models of large-scale climate dynamics. This project will conduct a comprehensive statistical analysis of a greater range of snow cover and cyclone observations in central/eastern North America, and evaluate hypotheses of the underlying mechanisms using numerical model simulations. These findings will then be used to address how this process is represented in climate models and identify changes to mid-latitude storm trajectories arising from past and projected retreats and advances of the mid-latitude snow line.Better understanding of how features of the Earth system, particularly snow cover, manifest in weather systems, will lead to improvements in both weather and climate forecasting and benefit risk management of weather hazards. New databases on snow cover and mid-latitude storm tracks will be made publicly and freely available. This project supports a PhD student and two undergraduate students who will be trained in the emerging field of the weather-climate interface.