Cirrus cloud has an important effect on the radiation balance between the earth’s surface and the atmosphere. The vertical structures, optical depth and effective lidar ratio of cirrus cloud detected by Mie scattering-polarization-Raman lidar system in Beijing from April 11 to December 31, 2012 are analyzed. The results show that the cloud height in Beijing is lower in spring and higher in autumn, with a mean value of about 8km. The mean of cloud thickness is 0.74km. The mean of optical depth is 0.092, and most observed cirrus cloud is thin while optical depth is less than 0.3. The effective lidar ratio of cirrus is lower in summer and higher in winter, inversely related to local temperature, with a mean value of 32.29Sr.
The atmospheric temperature is an important meteorological parameter. The rotational Raman lidar temperature measurement system is usually used for retrieval of atmospheric temperature according to the echo signal intensity ratio. UV double grating monochromator (DGM) is a kind of spectroscopical equipment for extracting the rotational Raman's spectra. The UV DGM consists of optical fibers , focal plates , lenses and gratings. Correct parameters of the gratings, lenses, fibers are essential to the successful development of DGM. First, a suitable grating is selected according to the grating diffraction theory. Second, the diameter and focal length of lens are chosen according to ruled area and blaze angle of grating, the numerical aperture of fiber and how difficult machining is . Finally, the range of fiber core diameter is chosen according to the distance between the sixth and the twelfth spectral line on the focal plane. In order to compare the different fiber core diameter's statistical temperature error, and suppression ratio of elastic scattering light, some numerical calculations are conducted. The simulation results show that the measurement accuracy increases in the evening and approximately decreases during daytime with the increase of input fiber core diameter .As the input fiber core diameter increases, the rejection ratio is decreasing ,but they are all more than 7 orders of magnitude. It is preferable to choose input fiber with core diameter of 300um during the daytime and 600um at night. The correct parameters of grating, lens and fiber provide theoretical basis for the development of the UV DGM.
Raman frequency shifter is a useful method extending laser wavelength the first Stokes of CH<sub>4</sub>, H<sub>2</sub>, and D<sub>2</sub> pumped by the fourth harmonic of Nd:YAG laser can be used in DIAL measurement of the trace gases. The stability and energy of SRS are related to focal length of lens active gas pressure input energy buffer gas elements and pressure. We detect the stability and energy of the first Stokes line under pure active and mixture with Ar or He. From our experiment the stability of pure CH<sub>4</sub>, H<sub>2</sub> are almost same under different pressure however the stability of pure D<sub>2</sub> changes with pressure. The energy conversion efficiency on Si is different among pure gas (CH<sub>4</sub>, H<sub>2</sub>, D<sub>2</sub>). Furthermore the optimal output energy of the first Stokes line of CH<sub>4</sub>, H<sub>2</sub>, D<sub>2</sub> are got independently at moderate active gas pressure mixing with moderate buffer pressure.
A new applied differential absorption lidar system for measurement of SO<sub>2</sub> and O<sub>3</sub> in the lower troposphere is developed. The emission wavelengths 289.04, 288.38 and 299.05 nm are obtained by stimulated Raman shifting of a Nd:YAG laser. The concentrations of SO<sub>2</sub> and O<sub>3</sub> have been measured quasi-simultaneously by use of the three wavelengths for compensating measurement results each other. The lidar measurements agree with in situ measurements. The measurement errors, which are primarily attributable to statistical error and variations in atmospheric backscattering intensity during the experiment, are discussed.