A sodar for profiling in a spatially inhomogeneous urban environment A sodar for profiling in a spatially inhomogeneous urban environment
A sodar for profiling in a spatially inhomogeneous urban environment A sodar for profiling in a spatially inhomogeneous urban environment
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用于在空间不均匀的城市环境中进行剖面分析的声雷达 用于在空间不均匀的城市环境中进行剖面分析的声雷达
DOI：
10.1127/metz/2015/0657
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发表时间：
2015
影响因子：
1.2
通讯作者：
Bradley S
中科院分区：
文献类型：
--
作者：
Bradley S
树冠上方的城市边界层仍然知之甚少。考虑到水平和垂直方向的空间和时间不均匀性，挑战之一是通过在屋顶上方几米以上的地方采样来获取数据。声雷达通常是地面遥感风和湍流的有用工具，但依赖于水平均匀性（如激光雷达）通过对三个或更多空间分离的体积进行采样来建立三分量风矢量。声音传播到 200 米的典型范围并返回所需的时间也是一个限制。研究了一种完全不同设计的声雷达，旨在解决这些问题。它具有单个垂直传输的声音脉冲。使用麦克风从发射波束周围的多个体积接收多普勒频移信号，每个麦克风在稍微偏离垂直的天顶角处具有严格的角度灵敏度。因此，采样体积的空间分布更小。通过比传统声雷达拥有更多的接收麦克风，可以抵消较小天顶角的影响。使用单个垂直发射光束而不是通常的多个光束也可以进行更快速的分析。描述了原型设计以及初始现场测量。研究发现，与预期相比，使用单碟天线的波束形成和声脉冲顺风漂移都会导致性能下降。结论是，虽然新型声雷达原则上可以工作，但设计中出现的妥协意味着预期的优势尚未实现
The urban boundary layer, above the canopy, is still poorly understood. One of the challenges is obtaining data by sampling more than a few meters above the rooftops, given the spatial and temporal inhomogeneities in both horizontal and vertical. Sodars are generally useful tools for ground-based remote sensing of winds and turbulence, but rely on horizontal homogeneity (as do lidars) in building up 3-component wind vectors from sampling three or more spatially separated volumes. The time taken for sound to travel to a typical range of 200 m and back is also a limitation. A sodar of radically different design is investigated, aimed at addressing these problems. It has a single vertical transmitted sound pulse. Doppler shifted signals are received from a number of volumes around the periphery of the transmitted beam with microphones which each having tight angular sensitivity at zenith angles slightly off-vertical. The spatial spread of sampled volumes is therefore smaller. By having more receiver microphones than a conventional sodar, the effect of smaller zenith angle is offset. More rapid profiling is also possible with a single vertical transmitted beam, instead of the usual multiple beams.A prototype design is described, together with initial field measurements. It is found that the beam forming using a single dish antenna and the drift of the sound pulse downwind both give rise to reduced performance compared with expectations. It is concluded that, while the new sodar works in principle, the compromises arising in the design mean that the expected advantages have not been realized