Special Topic | Application of LiDAR Technology in Atmospheric Detection

Atmospheric lidar

Atmospheric lidar is an application specific to lidar, which uses the interaction of Laser light with atmospheric components for detection. A radar with a laser as a light source, a photodetector as a receiving device, and an optical telescope as an antenna. The working principle of lidar monitoring the ambient atmosphere is: the laser emits laser pulses, and generates backscattering signals after interacting with aerosols and various components in the atmosphere. The detectors in the system receive echo signals and process and analyze them. In order to obtain the required atmospheric physical elements.

As the upstream component of lidar, laser is an important part of lidar. The performance, cost, and reliability of lidar products are closely related to the performance, cost, and reliability of lasers. There are many types of lasers with different parameters and performances. Which laser to choose as a radar radiation source often needs to be considered in combination with various factors, such as: wavelength, atmospheric transmission characteristics, single pulse energy/power requirements, volume, and reliability. sex and so on.

The lidar technology used to detect atmospheric particles is mainly meter scattering detection technology and polarization detection technology. The lidar using these two technologies is called meter scattering lidar and polarization lidar respectively. The echo signals received by these two types of lidar are elastic scattering signals, that is, the wavelength of the atmospheric backscatter echo is the same as that of the emitted laser pulse, and the detection height is about 0-20km.
The meter-scattering lidar mainly uses the back-scattering echo signal of the atmospheric aerosol to detect the distribution of its extinction coefficient or back-scattering coefficient. By solving the meter scattering lidar equation, the extinction coefficients of atmospheric aerosol particles and cloud particles at corresponding heights can be retrieved.
Polarization lidar is an effective tool to study the morphology of atmospheric non-spherical particles such as cirrus clouds and dust aerosols by detecting the depolarization ratio of the backscattered light of non-spherical particles to study their morphology. At the same time, polarized lidar also has the function of general meter scattering lidar, which can use the parallel component of detected atmospheric backscattered light to retrieve the vertical profile of cirrus and atmospheric aerosol extinction coefficient and the optical thickness of atmospheric aerosol.