Winter Precipitation Microphysics with Polarimetric Radar and Explicit Modeling

利用偏振雷达和显式建模进行冬季降水微物理研究

• 批准号: 1143948
• 负责人: Alexander Ryzhkov
• 金额: $ 37.03万
• 依托单位: University of Oklahoma Norman Campus
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-06-15 至 2017-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1143948&HistoricalAwards=false
• 关键词: Winter; Precipitation; Microphysics; Polarimetric; Radar

The advent of more routinely available dual-polarization radar measurements available both via a variety of research radars and operationally (e.g., to be provided by NOAA's upgraded WSR-88D network) offers an important emerging opportunity for cross-comparison of these observations and associated modeling, especially in cool-season environments involving frozen or mixed precipitation that have not been thoroughly studied. The goals of this effort are to document and interpret dual-polarization radar signatures in winter storms and to quantify the impact of various winter microphysical processes on observed patterns of polarimetric radar variables. These goals will be attained by synthesizing polarimetric radar observations and thermodynamic data, 2-D video disdrometer measurements, electromagnetic scattering calculations, and output from spectral (bin) microphysics models. S everal unique datasets of winter precipitation events scanned contemporaneously with polarimetric radars operating at S-, C- and X-band wavelengths have already been collected that reveal new signatures which hold great scientific and practical promise. One of these signatures, heretofore undocumented but repeated in several winter storm cases, involves development of a "secondary" bright-band signature that is apparently caused by ice crystals generated or associated with the refreezing of melted or partially-melted hydrometeors into ice pellets. Additionally, future winter storms will be observed using the polarimetric prototype WSR-88D radar in Norman, Oklahoma (KOUN), the newly-installed narrow beam University of Oklahoma Polarimetric Radar for Innovations in Meteorology and Engineering (OU-PRIME), and a mobile X-band polarimetric radar (NOXP) shared by NOAA's National Severe Storms Laboratory and the University of Oklahoma. Two major objectives will be addressed in the study. First, polarimetric observations of winter storms from multiple radars operating at diverse wavelengths will be combined with thermodynamic data from soundings and numerical weather model analyses to describe and interpret observed polarimetric signatures, and repetitive signatures will be documented to develop a more complete polarimetric portrait of winter storms. Second, one- and two-dimensional explicit "bin" and bulk microphysics models will be constructed to explore and quantify the role of microphysical processes such as depositional growth, aggregation, riming, melting, and refreezing in winter precipitation, and in-turn to better determine their representation by radar-observed variables. These bin models will be applied in an effort to quantitatively reproduce observed winter storm structure by pairing model output with electromagnetic scattering calculations. The Intellectual Merit of this effort will rest in improved understanding of the roles of dendritic growth, particle riming and aggregation aloft, processes including melting and re-freezing near the surface, which will contribute to improved bulk microphysics parameterizations used in numerical models. In turn, this will lead to better quantitative precipitation forecasts and forecasts of winter weather hazards. Improved interpretation of ground-based remote sensing of winter clouds and precipitation physics, including the melting layer, may help NASA satellite precipitation estimation and climate studies. Additionally, a better understanding of polarimetric radar measurements in winter storms may lead to an improved hydrometeor classification algorithm for winter weather. Broader impacts will include improved diagnosis and discrimination of contrasting winter precipitation types and their diagnosis via both ground-based and satellite-borne remote sensing techniques. These advances will in-turn have considerable value to the surface and aviation transportation communities, and thus contribute toward improved public safety.

更常规可用的双极化雷达测量的出现可通过各种研究雷达和操作（例如，由NOAA的升级WSR-88 D网络提供）提供了一个重要的新兴机会，这些观测和相关的模拟，特别是在冷季环境中，涉及冻结或混合降水，尚未得到彻底的研究。 这项工作的目标是记录和解释冬季风暴中的双极化雷达特征，并量化各种冬季微物理过程对观测到的极化雷达变量模式的影响。 这些目标将通过合成极化雷达观测和热力学数据，2-D视频disdrometer测量，电磁散射计算，并从光谱（箱）微观物理模型的输出。已经收集了与S-，C-和X-波段波长的偏振雷达同时扫描的冬季降水事件的几个独特的数据集，这些数据集揭示了具有巨大科学和实用前景的新特征。 其中一个迄今没有记录但在几个冬季风暴案例中重复的特征是发展出一个“次级”亮带特征，这显然是由融化或部分融化的水凝物重新冻结成冰粒所产生的冰晶造成的。 此外，未来的冬季风暴将使用偏振原型WSR-88 D雷达在诺曼，俄克拉荷马州（KOUN），新安装的窄波束俄克拉荷马州偏振雷达气象学和工程创新（OU-PRIME），和移动的X波段偏振雷达（NOXP）由NOAA的国家严重风暴实验室和俄克拉荷马州大学共享。 这项研究将涉及两个主要目标。 首先，从多个雷达在不同波长下运行的冬季风暴的偏振观测将与来自探测和数值天气模式分析的热力学数据相结合，以描述和解释观测到的偏振特征，并将记录重复的特征，以开发更完整的冬季风暴偏振肖像。 第二，一维和二维显式的“箱”和散装微物理模型将被构建，以探索和量化的作用，如沉积增长，聚集，霜，融化，并在冬季降水再冻结的微物理过程，并反过来，以更好地确定其代表性的雷达观测变量。 这些箱模型将应用于定量再现观测到的冬季风暴结构配对模型输出与电磁散射计算。这一努力的智力价值将在于提高对树枝状生长，颗粒边缘化和聚集的作用的理解，包括表面附近的熔化和重新冻结的过程，这将有助于改进数值模型中使用的大量微观物理参数化。 反过来，这将导致更好的定量降水预报和冬季天气灾害预报。 改进对冬季云层和降水物理学（包括融化层）的地面遥感的解释，可能有助于美国航天局的卫星降水估计和气候研究。此外，更好地了解偏振雷达测量在冬季风暴可能会导致一个改进的水凝物分类算法的冬季天气。 更广泛的影响将包括改进对对比鲜明的冬季降水类型的诊断和区分，以及通过地面和卫星遥感技术对这些类型的诊断。 这些进步将反过来对地面和航空运输界产生相当大的价值，从而有助于改善公共安全。