Squall line is a kind of common mesoscale disaster weather. At present, there are few studies on the elaborate detection of squall line by dual polarization radar. With the dual polarization upgrade of weather radar network, we need to study the relationship between squall line echoes of base data and polarization data to reveal new echo phenomena and formation mechanisms. The relationship between radar parameters and atmospheric physical processes also need to be examined. Based on the NUIST CDP radar, a squall line in the Yangtze and Huaihe River basin that occurred from July 30 to 31, 2014 is analyzed. The results show that polarization parameters have obvious advantages in the characteristics analysis of size, phase state, shape and orientation of the water condensate particles. The phase states of water condensate particles in convection cell can be distinguished through comparative discussion. Several phase states exist in the squall line, including small, medium and large raindrops, melting hails, dry hails and ice crystal particles and the Z_DR column can be used to identify the location of the main updraft. In addition, the polarization parameters are more sensitive to the melting layer. The gust front is presented as a narrow linear echo in Z affected by strong turbulence. It is an obvious velocity convergence line in V and approximately 0.70 in ρ_HV. The Z_DR can be used as a criterion to distinguish the horizontal and vertical scale of turbulence. The deforming turbulence, which is affected by environmental airflow, will cause an abnormally high Z_DR in the gust front and a negative Z_DR before and after the gust front. The variation of Z_DR depends on the turbulence arrangement, orientation and relative position between turbulence and radar. These dual polarization parameter characteristics offer insights into understanding the structure and evolution of the squall line.

线是一种常见的中尺度灾害天气。目前，关于双极化雷达精细探测线的研究很少。随着气象雷达网络双极化的升级，我们需要研究基础数据线回波与极化数据之间的关系，以揭示新的回波现象和形成机理。还需要检查雷达参数与大气物理过程之间的关系。基于NUIST CDP雷达，分析了2014年7月30日至31日发生在长江流域和淮河流域的线。结果表明，极化参数在冷凝水颗粒尺寸，相态，形状和取向特征分析中具有明显的优势。通过比较讨论可以区分出对流池中水凝结物颗粒的相态。qua线中存在几种相态，包括小，中和大雨滴，融化的冰雹，干冰雹和冰晶颗粒以及Z _DR列可用于标识主上升气流的位置。另外，偏振参数对熔融层更敏感。阵风锋表示为受强烈湍流影响的Z中狭窄的线性回波。它是一个明显的速度收敛线V在ρ和大约0.70 _HV。所述ž _DR可以用作一个准则，以区分紊流的水平和垂直缩放。受环境气流影响的变形湍流将导致阵风前沿的Z _DR异常高，而阵风前沿前后的Z _DR为负。Z的变化_DR取决于湍流的布置，湍流与雷达之间的方向和相对位置。这些双极化参数特性为了解understanding线的结构和演变提供了见识。