Azimuth angle variations of specular reflection echoes in the lower atmosphere observed with the MU radar
Azimuth angle variations of specular reflection echoes in the lower atmosphere observed with the MU radar
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DOI：
10.1016/s1364-6826(96)00058-2
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发表时间：
1997-05
影响因子：
1.9
通讯作者：
T. Tsuda;W. E. Gordon;Hideya Saito
中科院分区：
文献类型：
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作者：
T. Tsuda;W. E. Gordon;Hideya Saito
我们研究了对流层和平流层下层晴空回波的方位角变化，通过将MU雷达的天线波束转向12个位置来观察，方位角在天顶角为6°时每30°改变一次。回波强度的方位角变化在平流层下部的大高度范围内被识别出来，尽管有时也在对流层中发现它们，对流层近似为相当平滑的正弦曲线，在360°方位角中有一个或两个周期。此外，它们的结构随着时间和高度的变化而不断演变。平流层下部的变化范围一般较大，最大值与最小值之比有时超过 15 dB。大的方位角变化与回波功率的方位敏感性相关，表明它们是由镜面反射特性引起的，而不是局部湍流散射的影响，并表明反射表面呈波纹状，可能是重力波影响的结果。数值模型定性地解释了回波功率与方位角相关的基本行为，假设反射面的垂直位移呈现出由单色重力波的动力效应引起的正弦变化。
We studied azimuth angle variations of clear-air echoes in the troposphere and lower stratosphere, observed by steering the antenna beam of the MU radar into 12 positions, the azimuth angle being changed every 30 ° at a zenith angle of 6 °. Azimuth angle variations of the echo intensity were recognized in a large height range in the lower stratosphere, although they were also sometimes found in the troposphere, which was approximated by a fairly smooth sinusoidal curve, with one or two cycles in 360 ° azimuth angle. Moreover, their structure showed continuous progression with time and altitude. The range of variations was generally greater in the lower stratosphere, the ratio of the maximum to the minimum sometimes exceeding 15 dB. The large azimuth angle variations were associated with the aspect sensitivity of the echo power, suggesting that they were caused by the characteristics of specular reflection rather than the effects of localized turbulence scattering, and suggesting that the reflection surface was corrugated, probably the result of the effects of gravity waves. A numerical model qualitatively explained the fundamental behavior of the azimuth angle dependence of the echo power, it being assumed that the vertical displacement of the reflection surface showed sinusoidal variation caused by the dynamical effects of a monochromatic gravity wave.