Warm season diurnal precipitation over the plains east of the Rockies

落基山脉以东平原的暖季日降水量

• 批准号: RGPIN-2017-06229
• 负责人: Li, Yanping
• 金额: $ 1.6万
• 依托单位: University of Saskatchewan
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=657524
• 关键词: Warm; season; diurnal; precipitation; over

The plains east of the Rockies are central to global grain production and known as the Breadbasket of the World. These regions are subjected to a high frequency of extreme rainstorms with summer flooding frequently associated with heavy precipitation generated by convective and synoptic weather systems. However the rainfall diurnal cycle especially the nighttime rainfall maximum observed over the plains is poorly understood. The eastward propagating of the convective systems is also largely under-represented in current numerical weather prediction models. Compared to the US Great Plains, the summertime diurnal precipitation over the Canadian Prairies is relatively unexplored. ******My objectives are to address the following questions: 1) What are the dominant physical mechanisms that control the convection initiation, the peak time of the diurnal precipitation, as well as its systematic eastward propagation over the plains east of the Rockies in summer time? How can we incorporate these physical mechanisms to improve short-range, model-based forecasts of warm-season rainfall? 2) How can we appropriately reproduce the remote connection between the convection over the tropical western Pacific and the summer season precipitation over the Canadian Prairies in the model to improve the sub-seasonal climate prediction?******To achieve these goals, two PhD and one MSc students will be recruited to conduct comprehensive studies using field observations and remote sensing analysis, physical theory, as well as cutting-edge numerical modeling. ******The two PhD students will work on understanding the convective mechanisms and the eastward propagation of the precipitation over the plains in warm season. Specifically, one will focus on testing our novel Potential Vorticity hypothesis and exploring the effects of surface processes such as evapotranspiration on diurnal convection and convection initiation. The other will focus on the forecasting model calibration.******The MSc student will investigate the remote influence of the convection over the tropical Pacific Ocean on the warm season precipitation over the Prairies. With the appropriate representation of the tropical coupled ocean–atmosphere dynamics, the forecasting model will be able to reproduce this remote connection appropriately.******This work will advance the weather and climate forecast of warm-season precipitation over the Canadian Prairies. The improved prediction has the potential to inform operational practice through translating precipitation to surface hydrology and flooding information. This will improve our ability in planning for water resources distribution, water supply changes and disaster management, which will further benefit regional agriculture and food security as well as ecosystem sustainability. All of which have significant economic consequences. *****

落基山脉以东的平原是全球粮食生产的中心，被称为世界粮仓。这些地区遭受极端暴雨的频率很高，夏季洪水往往与对流和天气系统产生的强降水有关。然而，人们对平原上观测到的降雨日循环，特别是夜间最大降雨量知之甚少。在目前的数值天气预报模式中，对流系统的向东传播在很大程度上也没有得到充分的体现。与美国大平原相比，加拿大大草原的夏季日降水量相对较少。******我的目标是解决以下问题：1)控制对流开始的主要物理机制是什么，日降水的高峰时间，以及它在夏季在落基山脉以东平原上系统的向东传播？我们如何结合这些物理机制来改进暖季降雨的短期、基于模式的预报？2)如何在模式中适当再现热带西太平洋对流与加拿大草原夏季降水的远程联系，以改进亚季节气候预测？******为了实现这些目标，将招募两名博士和一名硕士学生，利用实地观测和遥感分析、物理理论以及前沿的数值模拟进行全面的研究。******两位博士研究生将研究暖季平原降水的对流机制和向东传播。具体来说，我们将重点测试我们的新位涡假设，并探索地表过程如蒸散发对日对流和对流起始的影响。二是预测模型的标定。******硕士学生将研究热带太平洋对流对大草原暖季降水的远程影响。通过适当地表示热带海洋-大气耦合动力学，预报模式将能够适当地再现这种远程联系。******这项工作将促进加拿大大草原暖季降水的天气和气候预报。通过将降水转化为地表水文和洪水信息，改进后的预测有可能为业务实践提供信息。这将提高我们规划水资源分配、供水变化和灾害管理的能力，这将进一步有利于区域农业和粮食安全以及生态系统的可持续性。所有这些都有重大的经济后果。＊＊＊＊＊