Extinction-to-backscatter ratio of Asian dust observed with high-spectral-resolution lidar and Raman lidar.
Extinction-to-backscatter ratio of Asian dust observed with high-spectral-resolution lidar and Raman lidar.
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DOI：
10.1364/ao.41.002760
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发表时间：
2002-05
期刊：
影响因子：
1.9
通讯作者：
Zhaoyan Liu;N. Sugimoto;T. Murayama
中科院分区：
文献类型：
--
作者：
Zhaoyan Liu;N. Sugimoto;T. Murayama
消光与后向散射比或激光雷达比是后向散射激光雷达反演问题的关键参数。 1998 年和 1999 年春季，使用高光谱分辨率激光雷达和拉曼弹性反向散射激光雷达组合观测了亚洲沙尘的激光雷达比。大多数情况下，测量值范围为 42 至 55 sr，平均值为 51 sr。这些值明显大于 Mie 计算所预测的值，该计算结合了测量的亚洲灰尘尺寸分布和折射率范围（典型值为 1.55-0.005i）。球体颗粒的 T 矩阵计算和许多其他理论研究表明，激光雷达比的提高主要是由于尘埃颗粒的非球形性。此外，城市气溶胶可能的污染也可能在光学薄的情况下有所贡献。米氏理论虽然可以很好地描述球形颗粒散射，但不足以代表亚洲尘埃等不规则颗粒的散射特性，特别是当尺寸参数较大时，在大于约90度的方向上。
Extinction-to-backscatter ratio or lidar ratio is a key parameter in the issue of backscatter-lidar inversions. The lidar ratio of Asian dust was observed with a high-spectral-resolution lidar and a combined Raman elastic-backscatter lidar during the springs of 1998 and 1999. The measured values range from 42 to55 sr in most cases, with a mean of 51 sr. These values are significantly larger than those predicted by the Mie computations that incorporate measured Asian dust size distributions and a range of refractive index with a typical value of 1.55-0.005i. The enhancement of lidar ratio is mostly due to the nonsphericity of dust particles, as indicated by the T-matrix calculations for spheroid particles and a number of other theoretical studies. In addition, possible contamination of urban aerosols may also contribute somewhat in optically thin cases. Mie theory, although it can well describe spherical particle scattering, will not be sufficient to represent the scattering characteristics of irregular particles such as Asian dust, especially in directions larger than approximately 90 degrees when the size parameter is large.