毫米波测云雷达的特点及其研究现状与展望

云在大气的能量分配、辐射传输，尤其是水循环系统中有不可忽视的作用。云探测对云物理、人工影响天气、气候变化和航空航天等领域有重要意义，是大气科学研究的热点之一。尽管目前已经发展了很多种遥感设备对云进行观测(如激光雷达、卫星、云幂仪等)，但这些设备无法得到高时空分辨率的云水平和垂直结构，而毫米波雷达是云三维精细结构探测的重要工具。由于毫米波雷达具有更接近小粒子尺度的短波长，因此更适合用来探测弱云，同时毫米波雷达也存在衰减严重的缺点。介绍了毫米波雷达的特点以及其探测小粒子的优势；对比分析了其与新一代多普勒天气雷达、晴空风廓线雷达的差异，得出：毫米波雷达具有高时空分辨率，能够更精确地反映云的垂直和水平结构，比普通天气雷达更适合监测云的变化。概括了国内外毫米波测云雷达的发展现状以及在云物理研究方面的情况，并展望了国内毫米波雷达未来研究的方向。

Characteristics about the Millimeter-Wavelength Radar and Its Status and Prospect in and Abroad

With the recent emphasis on understanding the role of clouds in the global radiation budget, cloud detection becomes more and more important. Although there are optical remote sensing techniques (e.g., satellite lidar, ceilometer, etc.) to measure cloud properties, optical signals cannot penetrate into thick cloud to observe the cloud′s horizontal and vertical dimensions and its internal structure. The scope of radar meteorology has expanded to include measurements of cloud properties and structure for radar′s wavelength is close to cloud′s diameter. Millimeter wavelength radar is recognized as having the potential to provide a more sensitive probe of cloud particles ranging from a few micrometers in diameter to precipitation drops. Since the backscatter cross section of tiny drops (i.e., several tens of micrometers in diameter) increases in proportion to λ 4, where  λ is the radar wavelength, cloud drops are more easily detected by radars of millimeter rather than centimeter wavelengths. On the other hand, attenuation of millimeter waves is much stronger, and the λ 4 advantage gained using millimeter waves is offset by the strong attenuation these waves experience. The 10 cm wavelength radar, used principally for storm warnings, cannot detect weak and no precipitation clouds well, compared with the mm radars. Compared to normal weather radar, millimeter wavelength radar has following superiorities in observing clouds: ①strong capability in detecting small particles like cloud, fog and dust; ②better resolution and precision of Doppler velocity; ③high special resolution result from its narrow beamwidth. In this paper, the status about cloud radar in and abroad about radars′ technology and application on clouds′ micro and macrophysics research, airports safe flight are introduced. Also present is a prospect on millimeter wavelength radar.