Guerrero-Rascado Juan Luis, Costa Maria João, Bortoli Daniele, Silva Ana Maria, Lyamani Hassan, Alados-Arboledas Lucas
Évora Geophysics Centre (CGE), University of Evora, Evora, Portugal.
Opt Express. 2010 Sep 13;18(19):20350-9. doi: 10.1364/OE.18.020350.
The most recent works demonstrate that the lidar overlap function, which describes the overlap between the laser beam and the receiver field of view, can be determined experimentally for the 355 and 532 nm channels using Raman signals. Nevertheless, the Raman channels cannot be used to determine the lidar overlap for the infrared channel (1064 nm) because of their low intensity. In addition, many Raman lidar systems only provide inelastic signals with reasonable signal-to-noise ratio at nighttime. In view of this fact, this work presents a modification of that method, based on the comparison of attenuated backscatter profiles derived from lidar and ceilometer, to retrieve the overlap function for the lidar infrared channel. Similarly to the Raman overlap method, the approach presented here allows to derive the overlap correction without an explicit knowledge of all system parameters. The application of the proposed methodology will improve the potential of Raman lidars to investigate the aerosol microphysical properties in the planetary boundary layer, extending the information of 1064 nm backscatter profiles to the ground and allowing the retrieval of microphysical properties practically close to the surface.
最新研究表明，描述激光束与接收器视场之间重叠情况的激光雷达重叠函数，可利用拉曼信号通过实验确定355纳米和532纳米通道的重叠函数。然而，由于拉曼通道强度较低，无法用于确定红外通道（1064纳米）的激光雷达重叠情况。此外，许多拉曼激光雷达系统仅在夜间提供具有合理信噪比的非弹性信号。鉴于此，本研究提出了该方法的一种改进，基于激光雷达和云幂仪得出的衰减后向散射剖面的比较，以获取激光雷达红外通道的重叠函数。与拉曼重叠方法类似，这里提出的方法无需明确了解所有系统参数即可得出重叠校正。所提方法的应用将提高拉曼激光雷达在研究行星边界层气溶胶微物理特性方面的潜力，将1064纳米后向散射剖面的信息扩展至地面，并允许获取实际接近地表的微物理特性。
