为了实现对降水粒子尺度、形状、速度等微物理特征的同步测量, 提出了一种基于单帧双脉冲成像的降水粒子测量方法, 并搭建了降水微物理特征测量仪样机, 该样机由脉冲光源、面阵图像传感器、以数字信号处理(DSP)芯片为核心的采集与控制单元、数据处理单元组成。然后研究了利用点扩散函数进行图像复原的方法, 以及利用曝光参数进行粒子捕获概率修正的方法, 并利用定标小球进行了检验。最后使用该仪器在南京地区进行了降雨外场实验, 并与OTT雨滴谱仪进行对比。实验结果表明: 仪器可以同步测量雨滴的形状、轴比、速度与尺度等微物理特征, 与经验模型具有良好的一致性; 与OTT雨滴谱仪的雨滴谱分布和降雨强度有很好的一致性, 二者测量降雨强度的标准偏差为1.57 mm/h, 相关系数达到96 %。该仪器对降水微物理特征具有更好的测量效果, 可以在野外长期无人值守运行, 在大气物理研究、数值天气预报模式、水文学研究等领域有着广阔的应用前景。

In order to realize synchronize measurement of size, shape, fall velocity and other micro-physical characteristics of precipitation particles, an imaging method based on the double exposures in one frame was proposed, and a Precipitation Micro-physical Characteristics Sensor (PMCS) was established. The PMCS prototype consisted of pulse light source, planar array image sensor, signal processing and control unit with a Digital Signal Processor (DSP) as the core and data processing unit. Then an image restoration method based on the point spread function and capture probability correction approach using exposure parameters were investigated and verified with calibration balls. Finally, the PMCS was employed to field experiments in Nanjing, where the measurement results were compared with the one of OTT distrometer. The results indicate that the PMCS is able to measure the shape, axis ratio, size and fall velocity of raindrops effectivity accurately and synchronously. The measured values of those characteristics are hihly consistent with empirical models. The raindrop size distribution and rainrate measured by PMCS and OTT disdrometer show good consistency for the average error of rainrate is 1.57 mm/h and the correlation coefficient can reach 96 %. The proposed instrument can provide comprehensive measurement of micro-physical features and realize unattended long-term stable operation, thus having a promising prospect in the fields such as atmospheric physics, numerical weather forecasting model, hydrological research and etc.