多普勒天气雷达双PRF径向速度资料质量控制

Quality Control of Dual PRF Velocity Data for Doppler Weather Radars

双PRF技术可用于扩展多普勒天气雷达不模糊速度的间隔,但是它也会导致径向速度资料受到离散奇异值的污染,在使用径向速度资料之前,需要对其进行质量控制。通过计算每个库的径向速度与其局地中值速度的差值,定量分析了CINRAD-SA、SC、CD和CC型业务多普勒天气雷达在双PRF模式下的径向速度数据质量,在此基础上提出了一种三步式的双PRF径向速度资料质量控制算法,即首先基于回波尺度大小对径向速度资料中的孤立噪声进行过滤,其次基于局地连续性原则对落在扩展不模糊速度间隔之外的模糊速度进行速度退模糊,最后基于已知的双PRF径向速度数据错误特征进行奇异值修正,并利用CINRAD-SA、SC、CD和CC型多普勒天气雷达的双PRF径向速度资料对该算法进行了测试。数据分析结果表明绝大部分点的速度都遵循连续性原则,与其局地中值速度的偏差较小或几乎没有偏差,而那些奇异值点的速度与其局地中值速度的偏差和高、低PRF的最大不模糊速度对应。对算法进行测试的结果表明该算法能有效地处理模糊速度并合理地修正速度奇异值。使用本算法对双PRF径向速度资料进行质量控制后,在保持原有数据空间分辨率不变的情况,径向速度数据质量得到显著提高。

The dual pulse repetition frequency（dual PRF）technique is available to extend the unambiguous velocity interval of Doppler weather radar,but the velocity data are typically contaminated by discrete outliers in large areas of high quality data.The quality control is needed before using the radial velocity data.The radial velocity data from CINRAD-SA,SC,CC and CD type Doppler weather radar running in dual PRF mode have been analyzed quantitatively through calculating the deviations of each radial velocity from its local median velocity.On this basis,a three-step postprocessing algorithm is proposed.First of all,the dual PRF velocity data are filtered based on the size to remove the isolated noise.Secondly,aliased velocity data that fall outside of the extended unambiguous velocity interval are unfolded using local continuity constraints.And lastly,using the known error characteristics of the dual PRF velocity data,velocity outliers are corrected in an efficient way.The algorithm has been tested using dual PRF velocity data from CINRAD-SA,SC,CD and CC type Doppler weather radars.The results of dual PRF velocity data analysis show the vast majority of the analyzed points obeys local continuity with hardly any deviation or small deviation from the local median velocity,the fraction of outliers are centered at different velocity deviations which roughly match the unambiguous intervals of the low PRF and high PRF measurements.The results of the algorithm testing show that it can correct effectively aliased velocities and discrete outliers caused by dual PRF mode.After quality control using this algorithm,high quality velocity data with changeless spatial resolution are produced.