ABSTRACT
The global occurrence of cirrus clouds can reach as high as 30%, whose scattering properties are essential impact on the climatic model, radiative transfer, and remote sensing. Their scattering properties are determined by the ice crystal shape, size distribution, refractive index and so on. Retrieval of the backscattering color ratios of cirrus cloud using a 355, 532 and 1 064 nm three-wavelength lidar, combined with the simulation of the three backscattering color ratios of different ice crystal shape, the shape of the lidar-measured ice crystal can be estimated. The results indicate that the shape of cirrus cloud over Hefei city is mostly composed by aggregates.
ABSTRACT
It is a new skill to use SRS rays as emitting waves for the lidar monitoring CO2 gas, and the nonlinear Raman lidar based on the SRS process was devised. The third harmonic Nd: YAG laser wave (354.7 nm) was injected into the Raman cells filled with higher pressure gases, CO2 and N2. The first Stokes (S1) line 371.66 nm (CO2) and 386.7 nm (N2) were generated by stimulated Raman scattering. The variable S1 energy was measured by changing the gas pressure in the Raman cell andthe Nd:YAG laser system output energy. The optimum pressures of the CO2 and N2 in the Raman cell were achieved. Moreover, the principles of this physical process were put forward. This skill has been applied to the lidar for monitoring the CO2 gas.
