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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.

Fine particles (PM2.5) affect human life and activities directly; the detection of PM2.5 mass concentration profile is very essential due to its practical and scientific significance (such as the quantification of air quality and its variability as well as the assessment of improving air quality forecast). But so far, it has been difficult to detect PM2.5 mass concentration profile. The proposed methodology to study the relationship between aerosol extinction coefficient and PM2.5 mass concentration is described, which indicates that the PM2.5 mass concentration profile could be retrieved by combining a charge-coupled device (CCD) side-scatter lidar with a PM2.5 sampling detector. When the relative humidity is less than 70 %, PM2.5, mass concentration is proportional to the aerosol extinction coefficient, and then the specific coefficient can be calculated. Through this specific coefficient, aerosol extinction profile is converted to PM2.5 mass concentration profile. Three cases of clean night (on 21 September 2014), pollutant night (on 17 March 2014), and heavy pollutant night (on 13 February 2015) are studied. The characteristics of PM2.5 mass concentration profile at the near-ground level during the cases of these 3 nights in the western suburb of Hefei city were discussed. The PM2.5 air pollutant concentration is comparatively large close to the surface and varies with time and altitude. The experiment results show that the CCD side-scatter lidar combined with a PM2.5 detector is an effective and new method to explore pollutant mass concentration profile at the near-ground level.

A Multi Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) instrument was deployed in May and June 2016 at a monitoring station (37.18° N, 114.36° E) in the suburban area of Xingtai (one of the most polluted cities in China) during the Atmosphere-Aerosol-Boundary Layer-Cloud (A2BC) and Air chemistry Research In Asia (ARIAs) joint experiments to derive tropospheric vertical profiles of NO2, SO2, HONO, HCHO, CHOCHO and aerosols. Aerosol optical depths derived from MAX-DOAS were found to be consistent with collocated sun-photometer measurements. Also the derived near-surface aerosol extinction and HCHO mixing ratio agree well with coincident visibility meter and in situ HCHO measurements, with mean HCHO near-surface mixing ratios of ~ 3.5 ppb. Underestimates of MAX-DOAS results compared to in situ measurements of NO2 (~ 60 %), SO2 (~ 20 %) are found expectedly due to vertical and horizontal inhomogeneity of trace gases. Vertical profiles of aerosols and NO2, SO2 are reasonably consistent with those measured by a collocated Raman Lidar and aircraft spirals over the station. The deviations can be attributed to differences in sensitivity as a function of altitude and substantial horizontal gradients of pollutants. Aerosols, HCHO, and CHOCHO profiles typically extended to higher altitudes (with 75 % integrated column located below ~ 1.4 km) than did NO2, SO2, and HONO (with 75 % integrated column below ~ 0.5 km) under polluted condition. Lifted layers were systematically observed for all species, (except HONO), indicating accumulation, secondary formation, or long-range transport of the pollutants at higher altitudes. Maximum values routinely occurred in the morning for NO2, SO2, and HONO, but around noon for aerosols, HCHO, and CHOCHO, mainly dominated by photochemistry, characteristic upslope/downslope circulation and PBL dynamics. Significant day-to-day variations are found for all species due to the effect of regional transport and changes in synoptic pattern analysed with HYSPLIT trajectories. Low pollution was often observed for air masses from the north-west (behind cold fronts), and high pollution from the southern areas such as industrialized Wuan. The contribution of regional transport for the pollutants measured at the site during the observation period was estimated to be about 20 % to 30 % for trace gases, and about 50 % for aerosols. In addition, agricultural burning events impacted the day-to-day variations of HCHO, CHOCHO and aerosols.

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.

[ABSTRACT]Aerosol radiative properties are retrieved from the observed data using a ground based sky radiometer. The seansonal variations are discussed after a good validation using another sunphotometer. The derived results as input parameters are used to calculated aerosol radiative forcing (RF). The comparison between the measured flux and the modeled flux shows a good agreement at the surface. The mean values of RF due to aerosol at SFC, TOA, and in ATM during 2007 to 2010 are -33.9, -23.1, and 10.8 Wm-2, respectively. Because of high value in SSA, the relative RF kept in ATM is not so much though the large value of AOD over Hefei.

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.

[ABSTRACT]Cirrus clouds play an important role in Earth-atmosphere radiation budget through absorbing long-wavelength outgoing radiation from the earth and scattering short-wavelength incoming solar radiation which determined by their optical property. The optical parameters such as scattering and extinction of the cirrus clouds are related to their microphysical properties such as the complex refractive index, shape, and size distribution. A three-wavelength lidar is built in Hefei in China to study the optical and microphysical properties of the cirrus clouds which is a bistatic lidar system transmitting three laser beams at 355nm, 532nm and 1064nm wavelength simultaneously with a receiving Cassegrainian 14-inch telescope in diameter.

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.