Search

As the non-spherical particles could be distinguished from spherical particles easily from polarization lidar measurement, polarization lidar was widely employed in the atmospheric measurements. However, it is very difficult to retrial the particle properties quantitatively from depolarization measurement due to the complex vector scattering model and the calibration of depolarization measurement. In this paper, a method for depolarization calibration of polarization lidar was introduced, and the offset angle of the half-wave plate and gain ratio could be determined exactly by using fitting method. The simulation and lidar measurements indicate that the polarization lidar could be calibrated well by using this method.

Aerosol and water vapor are two important atmospheric parameters. The accurate quantification of diurnal variation of these parameters are very useful for environment assessment and climate change studies. A moveable, compact and unattended lidar system based on modular design is developed for aerosol extinction coefficients and water vapor mixing ratios measurements. In the southern suburbs of Beijing, the continuous observation was carried out by this lidar since the middle of the year of 2017. The lidar equipment is presented and the case study is also described in this paper. The observational results show that the lidar kept a very good status from the long-time continuous measurements which is suitable for networking especially in meteorological research field.

The Raman lidar has been developed and installed in the Beijing from November to December in 2014 for the observation of the spatial and vertical characteristics of aerosol and water vapor in the planetary boundary layer. During the experiments, the Raman lidar operates in the automatic and continuous mode with the spatial resolution of 7.5 m and the temporal resolution of 15 min. The observation results show that the aerosol extinction always increases along with the greater content of water vapor and the lower height of planetary boundary layer. It implies that the decrease of air quality in Beijing is associated with the water vapor in the air and the height of planetary boundary layer beside the enrichment of local and transported aerosols.

A high spectral resolution lidar(HSRL) based on injection-seeded laser and iodine absorption filter has been developed. The basic principle, data processing method and configuration of HSRL were introduced. The HSRL measurement of atmospheric transmission in cloud and dust cases were presented,and compared with the results retrieved by the traditional Fernald method. Due to the nonidentity in physical and optical properties of different aerosols and cloud, the lidar ratio assumed in Fernald method cannot agrees well with the real atmosphere and produces considerable error in atmospheric transmission. Utilizing different spectral width of molecular scattering and particle scattering, the HSRL could separate two kinds of signals with iodine filter. Therefore, HSRL can measure the atmospheric transmission quantitatively without the additional assumption of lidar ratio.

In this paper, Take R companies,which is located in Wuhan Economic and Technological Development Zone, for a example, through the employee type and design of the empirical analysis of welfare programs, noting that demand for workers type on the different effects of welfare programs, and through analysis of various types of employee benefits needs of the specific requirements in order to welfare programs designed to guide enterprises.

A method for the retrieval of the aerosol scattering coefficient profiles in boundary layer is presented.A bistatic lidar system(CCD Lidar)with charge coupled device(CCD)as the detector and laser as transmitter is constructed.Aerosol scattering images of a horizontal laser beam and a vertical laser beam from ground to 1.2 km are imaged based on the CCD lidar system.The relative atmospheric scattering phase function(SPF)can be obtained by the aerosol scattering image of the horizontal laser beam,and the aerosol extinction coefficient(AEC)profile is inverted using the relative SPF.The AEC measured by CCD lidar has shown good agreement with that measured by double wavelength polarization lidar(DWPL)in 400 m and 600 m.Four nighttime AEC profile contours observed in Hefei are given.CCD lidar needs no overlap correction,it has a high spatial resolution of 0.032 m/pixel,and is expected as a potential technique of aerosol detection in boundary layer.