Improved Precipitation Typing Using POSS Spectral Modal Analysis
Improved Precipitation Typing Using POSS Spectral Modal Analysis
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DOI：
10.1175/jtech-d-20-0075.1
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发表时间：
2021-01
影响因子：
2.2
通讯作者：
B. Sheppard;M. Thurai;P. Rodriguez;P. Kennedy;D. Hudak
中科院分区：
文献类型：
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作者：
B. Sheppard;M. Thurai;P. Rodriguez;P. Kennedy;D. Hudak
降水发生传感器系统（POSS）是一个小型的X波段多普勒雷达，测量传感器附近小体积降水的多普勒速度谱。该传感器记录的速度和功率的发生在1分钟内测量的每个频谱的模式的2D频率矩阵。这些模式的分布的质心，沿着与其他光谱参数，定义了一个数据向量输入到一个多判别分析（MDA）的降水类型的分类。这需要先验确定不同类型、粒度分布（PSD）和风速条件的训练集。一个软件模型结合POSS系统参数，粒子散射截面，和终端速度模型，模拟实时多普勒信号测量系统为不同的PSD和风速。这以与系统硬件相同的方式处理，以产生MDA训练集的模态质心分布的引导样本。MDA的结果进行了比较，从多角度雪花相机（MASC）在MASCRAD网站附近的伊斯顿，科罗拉多，并从格里利，科罗拉多的CSU-CHILL X波段雷达观测图像。在四个案例研究中，POSS成功地确定了降水过渡通过一系列的类型（雨，霰，有边的树突，聚集体，unrimed树突）。此外，还报告了两次单独的冰雹事件，并得到了图像的证实。
The Precipitation Occurrence Sensor System (POSS) is a small X-band Doppler radar that measures the Doppler velocity spectra from precipitation falling in a small volume near the sensor. The sensor records a 2D frequency of occurrence matrix of the velocity and power at the mode of each spectrum measured over 1 min. The centroid of the distribution of these modes, along with other spectral parameters, defines a data vector input to a multiple discriminant analysis (MDA) for classification of the precipitation type. This requires the a priori determination of a training set for different types, particle size distributions (PSDs), and wind speed conditions. A software model combines POSS system parameters, a particle scattering cross section, and terminal velocity models, to simulate the real-time Doppler signal measured by the system for different PSDs and wind speeds. This is processed in the same manner as the system hardware to produce bootstrap samples of the modal centroid distributions for the MDA training set. MDA results are compared to images from the Multi-Angle Snowflake Camera (MASC) at the MASCRAD site near Easton, Colorado, and to the CSU–CHILL X-band radar observations from Greeley, Colorado. In the four case studies presented, POSS successfully identified precipitation transitions through a range of types (rain, graupel, rimed dendrites, aggregates, unrimed dendrites). Also two separate events of hail were reported and confirmed by the images.