[Characteristics of Aerosol Vertical Distribution over the Yangtze River Delta Region of China in 2018].

Based on the lidar data provided by cloud-aerosol lidar and infrared pathfinder satellite observations (CALIPSO) from December 2017 to November 2018, the temporal and spatial variation characteristics of 532 nm aerosol extinction coefficient, aerosol depolarization ratio, aerosol color ratio, and various types of aerosols in the troposphere over the Yangtze River Delta region of China were analyzed in detail. The altitude variation of aerosol optical parameters showed that the extinction ability of aerosols was generally stronger in the lower troposphere than that in the upper troposphere, the shape of particles was generally more regular in the lower troposphere than that in the upper troposphere, and the size of particles was generally smaller in the lower troposphere than that in the upper troposphere. The seasonal variation of aerosol optical parameters showed that the extinction ability of aerosols in the upper troposphere was generally stronger in summer and autumn than that in winter and spring, the shape of particles below 2 km was generally more regular in summer and autumn than that in winter and spring, and the size range of particles in the upper troposphere was generally larger in summer and autumn than that in winter and spring. The occurrence frequency of polluted dust aerosols over the Yangtze River Delta throughout the year was the highest (37.4816%). The occurrence frequency of smoke aerosols, polluted continental aerosols, and clean marine aerosols in the troposphere was higher in summer and autumn than that in winter and spring. However, the occurrence frequency of dust aerosols in summer and autumn was relatively low.

[Characteristics Analysis of the Surface Ozone Concentration of China in 2015].

Surface ozone concentration data from 189 cities in China in 2015 were processed by ArcGIS software in order to obtain the characteristics of the surface ozone concentration, such as time and space, topographical features, temperature, etc. The trend for surface ozone concentration was a decrease followed by an increase in China in 2015. The concentrations during the four seasons followed the order:summer > autumn > spring > winter, and the maximum appeared in July. The ozone pollution of East China, South China, and North China were more serious than other regions in China. The variation of longitude had a small influence on the ozone concentration, while the influence of latitude is significant. According to the analysis contrasting three different topographies in the same latitude, the influence of topography on ozone concentration was negligible. Furthermore, the research found a significant positive correlation between surface ozone concentration and temperature.

A new eye-safe lidar design for studying atmospheric aerosol distributions.

This paper presents the design, eye-safe characteristics, and performance of a new eye-safe infrared lidar system for studying city fog. It includes a compact infrared (1574 nm) transmitter, a telescope receiver, and a computer to acquire, store, and process and analyze the measurement data. The development of such a system makes it possible for routine aerosol monitoring in a populated area using lidar technology. A simulation study and a field test show that the system was capable of aerosol monitoring in cities. This lidar system will be used to study the distribution of aerosol over an urban area of 100-200 km(2) and will be useful for routine multidimensional aerosol measurements with high resolution in an urban environment.

Trace atmospheric SO2 measurement by multiwavelength curve-fitting and wavelength-optimized dual differential absorption lidar.

We present a new differential absorption lidar (DIAL) method for atmospheric trace SO2 using multi-wavelength curve fitting. With this method we use five wavelengths around a SO2 absorption peak and obtain SO2 and O3 concentrations by fitting their absorption cross sections to measured DIAL and null results. A SO, concentration of 6 parts in 10(9) (ppb) was obtained for an altitude of 1050 m with 150-m range resolution. In addition, we optimized the wavelengths for dual-DIAL SO2 measurement and demonstrated a high sensitivity of <0.5 ppb with 300-m range resolution. Comparison of these two methods is also presented.

Sum-frequency-generation system for differential absorption lidar measurement of atmospheric nitrogen dioxide.

A sum-frequency-generation system for differential absorption lidar measurement of atmospheric nitrogen dioxide in the lower troposphere was developed. The system uses a combination of a pair of KD*P crystals and a tunable dye laser with LDS 765 dye pumped by the second harmonic of a Nd:YAG laser to generate lambdaon and lambdaoff alternatively. Compared with the conventional system that uses Coumarin 445 dye pumped by the third harmonic, the output energy and long-term stability were improved. By use of this system, atmospheric NO2 concentrations of approximately 10-50 ppb were measured, with an instrumental error of approximately 7 ppb.