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.

通过各种研究雷达和操作（例如，由 NOAA 升级的 WSR-88D 网络提供）提供更常规的双极化雷达测量的出现，为这些观测结果和相关建模的交叉比较提供了重要的新兴机会特别是在涉及冰冻或混合降水的冷季环境中，尚未得到彻底研究。 这项工作的目标是记录和解释冬季风暴中的双偏振雷达特征，并量化各种冬季微物理过程对偏振雷达变量观测模式的影响。 这些目标将通过综合偏振雷达观测和热力学数据、二维视频测距仪测量、电磁散射计算以及光谱（bin）微物理模型的输出来实现。已经收集了几个与在 S、C 和 X 波段波长下工作的偏振雷达同时扫描的冬季降水事件的独特数据集，这些数据揭示了具有巨大科学和实践前景的新特征。 其中一个特征迄今为止尚未记录在案，但在几个冬季风暴案例中重复出现，涉及“次级”亮带特征的发展，该特征显然是由融化或部分融化的水凝物重新冻结成冰粒而产生或与之相关的冰晶引起的。 此外，未来的冬季风暴将使用位于俄克拉荷马州诺曼 (KOUN) 的偏振原型 WSR-88D 雷达、新安装的俄克拉荷马大学气象与工程创新窄波束偏振雷达 (OU-PRIME) 以及移动X 波段极化雷达 (NOXP) 由 NOAA 国家强风暴实验室和俄克拉荷马大学共享。 该研究将解决两个主要目标。 首先，在不同波长下运行的多个雷达对冬季风暴的偏振观测将与来自探测和数值天气模型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，并且将记录重复的特征，以形成更完整的冬季偏振特征风暴。 其次，将构建一维和二维显式“箱”和体微物理模型，以探索和量化冬季降水中沉积生长、聚集、沸腾、融化和再冻结等微物理过程的作用，进而通过雷达观测变量更好地确定它们的表示。 这些箱模型将用于通过将模型输出与电磁散射计算配对来定量再现观测到的冬季风暴结构。这项工作的智力价值将在于更好地理解枝晶生长、颗粒边缘和高空聚集、包括表面附近的熔化和再冻结在内的过程的作用，这将有助于改进数值模型中使用的体微物理参数化。 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宇航局卫星降水估计和气候研究。此外，更好地了解冬季风暴中的偏振雷达测量结果可能会改进冬季天气的水凝物分类算法。 更广泛的影响将包括改进对对比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进行诊断。 这些进步反过来将为地面和航空运输界带来巨大价值，从而有助于改善公共安全。