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

窄冷锋雨带（NCFR）是在中纬度气旋中观测到的几种中尺度雨带之一。先前的研究表明，nfrs有可能产生非常强的降雨和大风。主要研究人员将利用先进的数值中尺度天气模式来模拟NCFR的动力学和微物理。NCFR沿着天气尺度的母锋嵌入，以明显的中尺度到微尺度结构为主，具有准周期性间隔的降水核，由很少或没有降雨的间隙隔开。以前的NCFR研究表明，雪晶的边缘对高空的霰生长和地面降雨非常重要。数值模型配置为模拟线对流，并包括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基于最近的观测证据，即上层风切变影响锋后雪带的霰生长，以及NCFR降水核的深度、雷达反射率和它们之间的距离之间存在很强的正相关关系。如果成功，这项研究将增加我们对这些能够产生恶劣天气的系统的基本物理学的理解。这可能最终导致更好的预测。* * *

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. ***