Short-Range Ensemble Forecasting of Quantitative Precipitation

9612487马伦美国天气研究计划(USWRP)是一个跨部门活动，旨在开展和实施必要的研究，以改善向国家提供的天气服务。根据这一计划，国家科学基金会和国家海洋和大气管理局正在联合评估和支持USWRP高度优先的研究。众所周知，大气是一个混沌系统。因此，随着预报的发展，任何数值天气预报模式的初始条件中的小误差都会放大。由于大气状态永远不能准确测量，初始条件总是包含误差，这些误差的大小和结构只能被估计。因此，存在一个可能的初始条件的无限谱，所有这些都与分析的不确定性一致。定义预测不确定性范围和改进预测的程序称为集合预测(EF)。EF涉及同时运行多个预报，但从不同的、同样可能的初始条件开始。首席研究员将讨论中尺度定量降水预报(QPF)短期预报的四个基本方面：估计当前业务预报模式对QPF的可预报性界限；调查稳健估计QPF概率密度函数预报演变所需的最小集合数量；对于QPF预报，确定模式差异相对于初始条件中的不确定性的相对重要性；确定在较低分辨率下使用短期集合预报相对于单一、高分辨率确定性预报的相对优点。首席调查员将与国家海洋和大气管理局内的科学家合作开展这项工作。这项研究的成功完成可能会大大提高预报降水的能力。***

9612487 Mullen The U.S. Weather Research Program (USWRP) is an interagency activity designed to perform and implement the research necessary to improve the delivery of weather services to the nation. Under this Program, the National Science Foundation and the National Oceanic and Atmospheric Administration are jointly evaluating and supporting research of high priority to the USWRP. It is well known that the atmosphere is a chaotic system. As a consequence, small errors in the initial conditions of any numerical weather prediction model amplify as the forecast evolves. Because the atmospheric state can never be measured exactly, initial conditions will always contain errors whose magnitude and structure can only be estimated. Hence an infinite spectrum of plausible initial conditions exists, all of which are consistent with analysis uncertainty. A procedure for defining the scope of forecasting uncertainty and improving forecasts is known as ensemble forecasting (EF). EF involves running multiple forecasts starting at the same time, but from different, equally-likely initial conditions. The Principal Investigator will address four fundamental aspects of short-range EF of quantitative precipitation forecasting (QPF) at the mesoscale: Estimate limits of predictability for QPF by current operational forecast models; Investigate minimum number of ensembles needed to robustly estimate forecast evolution of probability density function of QPF; For QPF forecasts, determine relative importance of model differences verses uncertainties in initial conditions; Determine the relative merit of using short range ensemble forecast at a lower resolution verses a single, high resolution deterministic forecast. The Principal Investigator will collaborate in this effort with scientists within the National Oceanic and Atmospheric Administration. Successful completion of this research could lead to substantial improvements in abili ty to forecast precipitation. ***