Sakai Tetsu, Nagai Tomohiro, Nakazato Masahisa, Mano Yuzo, Matsumura Takatsugu
Japan Society for the Promotion Science, Meteorological Research Institute, Nagamine 1-1, Tsukuba, Ibaraki 305-0052, Japan.
Appl Opt. 2003 Dec 20;42(36):7103-16. doi: 10.1364/ao.42.007103.
The tropospheric particle extinction-to-backscatter ratio, the depolarization ratio, and the water-vapor mixing ratio were measured by use of a Raman lidar and a polarization lidar during the Asian dust seasons in 2001 and 2002 in Tsukuba, Japan. The apparent (not corrected for multiple-scattering effects) extinction-to-backscatter ratios (Sp) showed a dependence on the relative humidity with respect to ice (RHice) obtained from the lidar-derived water-vapor mixing ratio and radiosonde-derived temperature; they were mostly higher than 30 sr in dry air (RHice < 50%), whereas they were mostly lower than 30 sr in ice-supersaturated air (RHice > or = 100%), where the apparent extinction coefficients were larger than 0.036 km(-1). Both regions showed mean particle depolarization ratios of 20%-22%. Comparisons with theoretical calculations and the previous experiments suggest that the observed dependence of Sp on RHice is attributed to the difference in the predominant particles: nonspherical aerosols (mainly the Asian dust) in dry air and cloud particles in ice-supersaturated air.
在2001年和2002年日本筑波的亚洲沙尘季节期间，利用拉曼激光雷达和偏振激光雷达测量了对流层粒子消光与后向散射比、退偏比和水汽混合比。表观（未校正多次散射效应）消光与后向散射比（Sp）显示出对从激光雷达导出的水汽混合比和无线电探空仪导出的温度得到的相对于冰的相对湿度（RHice）的依赖性；在干燥空气中（RHice < 50%），它们大多高于30 sr，而在冰过饱和空气中（RHice≥100%），它们大多低于30 sr，其中表观消光系数大于0.036 km-1。两个区域的平均粒子退偏比均为20%-22%。与理论计算和先前实验的比较表明，观测到的Sp对RHice的依赖性归因于主要粒子的差异：干燥空气中的非球形气溶胶（主要是亚洲沙尘）和冰过饱和空气中的云粒子。
