Dynamics and Microphysics of Narrow Cold-Frontal Rainbands as Investigated with a Three-Dimensional Cloud Model

用三维云模型研究窄冷锋雨带的动力学和微物理

• 批准号: 9633424
• 负责人: Pao-Kuan Wang
• 金额: $ 30.07万
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-04-01 至 2001-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9633424&HistoricalAwards=false
• 关键词: Dynamics; Microphysics; Narrow; Cold; Frontal

9633424 Wang The narrow cold frontal rainband (NCFR) is one of several types of mesoscale rainbands observed in mid-latitude cyclones. Previous studies have shown that NCFRs have the potential to produce very heavy rains and high winds. The Principal Investigators will utilize an advanced numerical mesoscale weather model to simulate the dynamics and microphysics of NCFR. Imbedded along the synoptic-scale parent front, NCFR's are dominated by well-marked mesoscale to microscale structure with quasi-periodically spaced precipitation cores separated by gaps containing little or no rain. Previous NCFR studies have shown that riming of snow crystals is highly important to graupel growth aloft and thus to surface rainfall. The numerical model is configured to simulate line convection and includes a three-class ice microphysics parameterization. Initial parameters of main interest will be mid- to upper-level environmental wind shear and the length of mesoscale waves perturbing the leading edge of the cold air. The choice of these two parameters is motivated by recent observational evidence that upper wind shear affects graupel growth in postfrontal snowbands and that strong positive correlations exist among the depth of NCFR precipitation cores, their radar reflectivity and the separation between them. If successful, this research will increase our understanding of the fundamental physics of these systems which are capable of producing severe weather. This may eventually lead to better predictions. ***

9633424 WANG窄冷锋雨带是中纬气旋观测到的几种中尺度雨带之一。以前的研究表明，NCFR有可能产生非常大的暴雨和大风。首席调查员将利用先进的中尺度数值天气模式来模拟NCFR的动力学和微物理。NCFR沿天气尺度母锋面嵌入，以明显的中尺度到微尺度结构为主，准周期间隔的降水中心由少雨或无雨的空隙隔开。NCFR之前的研究表明，雪晶的边缘对于高空的碎屑生长非常重要，因此对地表降雨也是如此。该数值模式被配置为模拟线对流，并包括一个三级冰微物理参数化。主要关注的初始参数将是中高层环境风切变和扰动冷空气前缘的中尺度波的长度。这两个参数的选择是因为最近的观测证据表明，高空风切变影响了锋后雪带的涡旋增长，NCFR降水核心的深度、雷达反射率和它们之间的间隔之间存在着很强的正相关关系。如果成功，这项研究将增加我们对这些系统的基本物理的理解，这些系统能够产生恶劣天气。这可能最终会带来更好的预测。***