Should Interpolation of Radar Reflectivity be Performed in Z or dBZ?
Should Interpolation of Radar Reflectivity be Performed in Z or dBZ?
复制标题
雷达反射率插值应在 Z 轴还是 dBZ 轴上进行？
DOI：
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发表时间：
2019
影响因子：
2.2
通讯作者：
A. Protat
中科院分区：
文献类型：
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作者：
R. Warren;A. Protat
将数据从原始球面坐标映射到笛卡尔网格时，需要对地面雷达测量进行插值。对于反射率，出现的问题是是否应以 Z (mm6 m−3) 或 dBZ 为单位执行此处理。这项研究使用来自三个雷达的一年数据来解决这个问题，这些雷达在澳大利亚不同的气候下运行。对于每个雷达，都会处理 800 个体积扫描的子集，以识别三个坐标方向（距离、方位角和仰角）中每个方向上的“三元组”（具有有效数据的三个连续门的组）。对于每个三元组，中央栅极的反射率是通过在 Z 和 dBZ 的外部两个栅极之间进行线性插值来估计的。然后将所得值与中央门处的真实反射率进行比较，以量化插值误差。对于所有三个站点和所有三个坐标方向，我们发现 Z 轴插值平均而言更准确，特别是在高反射率和强反射率梯度的区域（即对流核心）。然而，在低且单调增加/减少反射率的区域中，以 dBZ 为单位的插值效果更好。因此，建议在插值之前将反射率从 dBZ 转换为 Z，除非识别回波顶部高度或其他低反射率边界。
Interpolation of ground-based radar measurements is required when mapping data from their native spherical coordinates to a Cartesian grid. For reflectivity the question arises as to whether this processing should be performed in units of Z (mm6 m−3) or dBZ. This study addresses this question using one year of data from three radars, operating in diverse climates across Australia. For each radar, a subset of 800 volume scans is processed to identify “triads”—groups of three consecutive gates with valid data—in each of the three coordinate directions: range, azimuth, and elevation. For every triad, the reflectivity at the central gate is estimated by linearly interpolating between the outer two gates in both Z and dBZ. The resulting values are then compared with the true reflectivity at the central gate to quantify the interpolation errors. For all three sites and in all three coordinate directions, we find that interpolation in Z is more accurate on average, especially in regions of high reflectivity and strong reflectivity gradient (i.e., convective cores). However, interpolation in dBZ is better in regions of low and monotonically increasing/decreasing reflectivity. It is therefore recommended that reflectivities be converted from dBZ to Z prior to interpolation except when identifying echo-top height or other low-reflectivity boundaries.