零度层亮带的成因理论模拟与分析研究

Radar bright band has become an important basis for the identification of precipitation nature when weather radar detects precipitation .It is not only one of the main criteria in distinguishing freezing rain,but also an important symbol to the dissipation of a thunderstorm.And the band may lead to overestimation of precipitation and VIL. But comprehensive and quantitative research on radar bright band to take into account the multiphase non-spherical particles has long been obstructed because the calculation of the multiphase non-spherical particle's scattering characteristics has been too complicated to be realized. Therefore, it is of great significance in further research on radar bright band. The proposal is raised up for this, based on our achivements including a software called SimRAD( simulating radar detection and data processing) resulted from our last NSFC project，to create a comparitively thorough, simulative, microphysical study on the formation of a radar bright band. That is, non-spherical and inhomogeneous particle's scattering characteristics will be taken into account in the calculation and analysis of the cloud microphysical factors of the formation of radar bright band. The results obtained from simulation will be compared with the actual detections with dual-polarization Doppler radar and radiosonde. The effects of parameter settings on calculation, the formation mechanism, influencing factors and characteristics of the radar bright band are all to be discussed. It is hoped that the results will provide a promising perspective for theories and methods for radar detection and applications.

零度层亮带，在天气雷达观测中已成为降水性质识别的重要依据，也是冻雨识别的主要判据和雷暴云消散的重要标志，而且零度层亮带会引起雷达对降水量和VIL的过高估计。零度层亮带内部含有多相态、非球形粒子群，但因其散射特征计算复杂而一直难以在零度层亮带成因研究中全面定量计算。因此，零度层亮带的成因理论模拟与分析研究具有重要的理论意义和应用价值。本课题以课题组已结题NSFC项目开发的雷达探测及其数据处理仿真软件SimRAD为平台，把课题组多年来对非球形、非均质粒子散射特征和双线偏振多普勒天气雷达探测的研究成果，创新性地应用于零度层亮带形成的云微物理学因素模拟计算分析，并与双线偏振多普勒天气雷达资料及探空资料等实际探测资料相结合，检验模拟效果，探讨参数设置对模拟计算的影响，分析零度层亮带的形成机制、影响因素和特征，为利用雷达监测降水和VIL、识别冻雨、研究雷暴云消散过程中的微物理特征等提供理论依据和方法。

零度层亮带，是雷暴云即将消散的重要标志，又是识别冻雨的主要判据之一，而且“零度层亮带”会引起雷达对降水量的过高估计。因为在零度层亮带成因的定量研究中需要多相态、非球形粒子群散射特征等复杂计算而一直难以进行。因此，零度层亮带的成因理论模拟与分析研究具有重要的理论意义和应用价值。本项目以课题组已结题NSFC项目开发的雷达探测及其数据处理仿真软件SimRAD为平台，分析亮带形成的原因，同时把课题组多年来对非球形、非均质粒子散射特征、离散偶极子近似算法（DDA）和边缘粘连粒子的概念等研究成果创新性地融入到SimRAD平台来用于“零度层亮带”形成的云微物理学因素模拟计算分析，并与双线偏振多普勒天气雷达资料及探空资料等实际探测资料相结合，检验模拟效果、探讨参数设置对模拟计算的影响，分析零度层亮带的形成机制、影响因素和特征，为进一步提高雷达在雷暴云探测、冻雨识别、降水量监测等应用中的效果提供理论依据和方法。与此同时，在完善后的SimRAD平台的基础上，设计出层状云降水过程中基于天气雷达反射率因子进行雨滴谱的反演计算方案，在现有的实测雷达数据和滴谱数据下，分析检验并讨论该方法的适用性，这为进一步开发已有雷达观测数据的应用潜力提供技术支持。