Data from: Radar wind profilers and avian migration - a qualitative and quantitative assessment verified by thermal imaging and moon watching

1. Radars of various types have been used in ornithological research for about 70 years. However, the potential of radar wind profiler (RWP) as a tool for biological purposes remains poorly understood. The aim of this study is to assess the suitability of RWP for ornithological research questions.
2. A 1290 MHz RWP at the southeastern coast of the Bay of Biscay has been known to exhibit seasonally occurring nocturnal signals attributed to migrating birds. As a first step to verify the origin of these seasonal patterns, historical radar data from 2010-2012 were analysed, and both bird patterns and temporal occurrence were identified in RWP data at different levels of the signal processing. A thermal-imaging (TI) camera in conjunction with moon watching was used as verification systems at the radar site to confirm the ornithological origin of the radar echoes. The simultaneous data on spring migration served as a basis for the identification of biological signatures (qualitative parameters) on time series level (raw data) and to derive quantitative migration parameters (flight altitude, migration traffic rates) thereof. Finally the quantitative measurements of the TI camera and the radar were compared considering meteorological conditions.
3. The approach allowed identifying reproducible criteria based on time series to calculate migration traffic rates and altitudinal flight distribution. General flight directions were only available in the final wind data. In clear weather conditions the calibration methods coincided well with the wind profiler data.
4. Findings show that wind profiler raw data offers reliable information on migration intensity, flight altitudes and flight directions in a variety of meteorological conditions. The method presented can be applied as a complement to present efforts to use weather radars for large-scale bird monitoring. Furthermore it is also interesting for the meteorological community to refine signal-processing methods.

1. 各类雷达应用于鸟类学研究已有约70年历史。然而，雷达风廓线仪（Radar Wind Profiler, RWP）作为生物学研究工具的潜力仍未得到充分认知。本研究旨在评估RWP在鸟类学研究相关问题中的适用性。
2. 位于比斯开湾东南海岸的一台1290 MHz雷达风廓线仪，曾观测到季节性出现的夜间信号，该信号被认为源自迁徙鸟类。为验证这类季节性信号的来源，研究团队分析了2010-2012年的历史雷达数据，并在信号处理不同层级的RWP数据中识别出鸟类活动模式与时间分布特征。研究人员在雷达站部署热成像（TI）相机配合月球观测作为验证系统，以确认雷达回波的鸟类学起源。同时获取的春季迁徙同步数据，被用于在时间序列层面（原始数据）识别生物特征（定性参数），并据此推导定量迁徙参数（飞行高度、迁徙交通率）。最后，结合气象条件，对比了热成像相机与雷达的定量测量结果。
3. 本研究方法可基于时间序列确立可复现的判别准则，用于计算迁徙交通率与飞行高度的空间分布。仅在最终的风场数据中可获取鸟类的整体飞行方向。在晴朗天气条件下，校准方法与雷达风廓线仪的观测数据吻合度较高。
4. 研究结果表明，雷达风廓线仪的原始数据可在多种气象条件下，提供关于迁徙强度、飞行高度与飞行方向的可靠信息。本文提出的方法可作为现有利用天气雷达开展大规模鸟类监测工作的补充手段。此外，该研究对于气象学界优化信号处理方法亦具有参考价值。