Improvement of Quantitative Precipitation Forecasts Using a New Microphysical Parameterization

准确预报与破坏性、高影响天气事件相关的降水可以挽救生命和金钱。目前的预报精度受到数值天气预报（NWP）模式中微物理过程表现不佳的影响。本研究的目的是通过更好地制定微物理过程来改善区域尺度模式的定量降水预报（QPF）。该项目的中心假设是，通过一致的暖、冷和混合相云表示，可以显著改善复杂地形下的QPF。对所有生长过程的明确处理将产生更准确的质量分布和下降轨迹，从而导致更准确的雨和雪的空间分布。为了验证中心假设，研究人员将在两个先进的研究数值模型中实施改进的微物理方案，在理想化模拟中进行严格的敏感性研究，使用分析的数据集验证大雨和降雪事件的预测，使用统计上有意义的方法评估QPF和雨雪线预测的改进。测试模型性能，研究实时冬季风暴模拟中云系统的动力学和微物理的相互作用，并确定计算时间的增加与预测改进的比例。降雨和降雪量、多普勒和剖面雷达数据以及来自两个已经完成的实地项目的现场动态和微物理飞机测量数据将用于模型验证。新版本的微物理参数化将提供给科学界和雷诺当地的NWS办公室，在那里它的性能将在操作环境中进行测试。

Accurate forecasts of precipitation associated with disruptive, high-impact weather events can save lives and money. Current forecast accuracy suffers from poor representation of microphysical processes in numerical weather prediction (NWP) models. The goal of this research is to improve quantitative precipitation forecasts (QPF) in regional scale models through better formulation of microphysical processes. The central hypothesis of this project is that significant improvement in QPF in complex terrain can be reached through a consistent representation of warm, cold, and mixed-phase clouds. Explicit treatment of all growth processes will generate more accurate mass distributions and fall trajectories, leading to more accurate spatial distribution of rain and snowfall. To test the central hypothesis, the investigators will implement an improved microphysical scheme in two advanced, research numerical models, perform rigorous sensitivity studies in idealized simulations, validate forecasts of heavy rain and snowfall events using analyzed data sets, evaluate improvement in QPF and rain-snow line forecasts using statistically meaningful methods, test model performance and investigate the interaction of the dynamics and microphysics of cloud systems in real-time winter storm simulations, and determine the ratio of increase in computational time to forecast improvement.Rain and snowfall totals, Doppler and profiler radar data, as well as in situ dynamic and microphysical aircraft measurements from two already completed field projects will be used in model validation. The new version of the microphysics parameterization will be made available to the scientific community and the local NWS office in Reno, where its performance will be tested in an operational environment.