Atmospheric Structure and Radar Backscattering in Clear Air
Atmospheric Structure and Radar Backscattering in Clear Air
复制标题
晴空中的大气结构和雷达后向散射
DOI：
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发表时间：
1969
期刊：
影响因子：
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通讯作者：
H. Óttersten
中科院分区：
文献类型：
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作者：
H. Óttersten
本文总结了晴空中折射率不规则性的雷达后向散射及其与大气结构和湍流的关系。雷达气象学的这门新学科起源于雷达角度研究和解释这些神秘回波的努力。镜面大气雷达反射的意义现在看来是有限的，因此，这项研究完全致力于雷达后向散射的湍流波动在晴朗的空气折射率。大气湍流分为两种状态：（1）在对流域中，来自水汽波动的后向散射勾勒出与浮力潮湿空气包相关的规则三维晴空结构;（2）在稳定状态中，水平分层晴空回波源于由于风切变产生的湍流混合在静态稳定性增强的区域中引起的水汽和/或温度扰动。给出了一般情况下，各向同性的情况下，和惯性子范围的雷达反射率和折射率的微观结构之间的理论关系。的微观结构和大气平均场之间的连接示出了一个简化的情况下，在稳定的制度，这种关系提供了洞察雷达后向散射从晴空湍流（CAT）。它的结论是，强CAT将与区域的折射率变化和增强的雷达回波。本文简要介绍了雷达方法在晴空研究中的应用，并总结了晴空结构的特征。
This study summarizes advances in radar backscattering from refractive index irregularities in the clear air and its relationship to atmospheric structure and turbulence. This recent discipline of radar meteorology originated from radar angel studies and the efforts to explain these mysterious echoes. The significance of specular atmospheric radar reflections now appears limited, and consequently this study is devoted entirely to radar backscattering from turbulent fluctuations in the clear-air refractive index. Two regimes of atmospheric turbulence are distinguished: (1) in the convective domain, backscattering from water vapor fluctuations outlines regular, three-dimensional clear-air structures associated with buoyant, moist air parcels; (2) in the stable regime, horizontally stratified clear-air echoes originate from water vapor and/or temperature perturbations due to wind-shear-generated turbulent mixing in zones of enhanced static stability. Theoretical relationships are given between the radar reflectivity and the refractive index microstructure for the general case, for the isotropic case, and for the inertial subrange. The connection between the microstructure and the atmospheric mean fields is illustrated for a simplified situation in the stable regime; this relationship provides insight to the radar backscattering from clear-air turbulence (CAT). It is concluded that strong CAT will be associated with zones of increased refractive index variability and enhanced radar returns. A brief resume of experimental work illustrates the application of radar methods in clear-air research and summarizes characteristic features of clear-air structures.