Validating Precision Estimates in Horizontal Wind Measurements from a Doppler Lidar
Validating Precision Estimates in Horizontal Wind Measurements from a Doppler Lidar
复制标题
验证多普勒激光雷达水平风测量的精度估计
DOI：
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发表时间：
2016
期刊：
影响因子：
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通讯作者：
J. Lundquist
中科院分区：
文献类型：
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作者：
R. Newsom;W. Brewer;J. Wilczak;D. Wolfe;S. Oncley;J. Lundquist
抽象的。最近的一次现场活动的结果用于评估多普勒激光雷达风检索算法产生的风速和风向精确估计的准确性。该算法基于传统的速度方位角显示 (VAD) 技术，假设输入数据（即径向速度）受到随机零均值误差的影响，使用标准误差传播技术估计风速和风向测量精度。在本研究中，激光雷达被配置为在 6 周的部署期间每 12 分钟执行一次 8 光束计划位置指示器 (PPI) 扫描。使用不同的方案进行了几次风反演试验，以估计径向速度测量的精度。将所得的风速和风向精度估计值与 VAD 算法和附近 300m 塔上的声波风速计测量之间的风速和风向差异进行比较。所有试验都产生了质量相似的风场，偏差可以忽略不计，但风速和风向精度场却有很大不同。当直接计算沿 PPI 扫描的每个指向方向和距离门的径向速度标准偏差来确定径向速度精度时，可以获得最准确的风速和风向精度。相比之下，当假设仪器测量精度是对径向速度精度的唯一贡献时，反演结果导致风速和风向精度偏差过低，并且数据质量指标较差。
Abstract. Results from a recent field campaign are used to assess the accuracy of wind speed and direction precision estimates produced by a Doppler lidar wind retrieval algorithm. The algorithm, which is based on the traditional velocity-azimuth-display (VAD) technique, estimates the wind speed and direction measurement precision using standard error propagation techniques, assuming the input data (i.e., radial velocities) to be contaminated by random, zero-mean, errors. For this study, the lidar was configured to execute an 8-beam plan-position-indicator (PPI) scan once every 12 min during the 6-week deployment period. Several wind retrieval trials were conducted using different schemes for estimating the precision in the radial velocity measurements. The resulting wind speed and direction precision estimates were compared to differences in wind speed and direction between the VAD algorithm and sonic anemometer measurements taken on a nearby 300 m tower. All trials produced qualitatively similar wind fields with negligible bias but substantially different wind speed and direction precision fields. The most accurate wind speed and direction precisions were obtained when the radial velocity precision was determined by direct calculation of radial velocity standard deviation along each pointing direction and range gate of the PPI scan. By contrast, when the instrumental measurement precision is assumed to be the only contribution to the radial velocity precision, the retrievals resulted in wind speed and direction precisions that were biased far too low and were poor indicators of data quality.