The latest research progress of international dual-angle, multi-angle and polarization aerosol satellite remote sensing inversion algorithms are reviewed. As a special case of multi-angle remote sensing, the core idea of inversion algorithm for dual-angle aerosol remote sensing can also be applicable to the situation where two sensors are observing the same area almost simultaneously. Taking the dual-angle observation along-track scanning radiometer (ATSR) series sensor as an example, the algorithm principles and latest research progress of the typical aerosol inversions, including ATSR dual view (ADV), Swansea University (SU) and Oxford-RAL aerosol and cloud (ORAC) optimal estimation inversion algorithms, are summarized systematically. On this basis, taking the current international spaceborne and airborne sensors with multi-angle observations as examples, the latest research progress of spaceborne multi-angle scalar inversion algorithms and spaceborne and airborne multi-angle polarization inversion methods are further summarized and discussed, respectively. By this means, the application advantages and potential of satellite and airborne multi-angle (including dual-angle) sensors in aerosol remote sensing research are explored and demonstrated, which provides an effective reference and key support for the design and development of multi-angle and polarization remote sensing inversion algorithms in China.

A transported dust case was investigated by using the data of PM2.5 and PM10 from ground monitoring stations and the observation results with 532 nm polarization lidar. Entrainment and convective mixing processes, which were found to play an important role in re-distributing the dust particles, were depicted in detail. At the early stage of the dust episode, dust particles were lifted above 1 km. After the evolution of planetary boundary layer at daytime, the dust particles were entrained into the boundary layer and evenly distributed by convective mixing. At the end of the dust case, the pollution from North China Plain arrived at Wuhan bringing about 4300 tons of anthropogenic aerosols, which is about ten times of the total content of urban aerosols in Wuhan during the 7th CISM Military World Games.

In the rough sublayer of the urban boundary layer, the local similarity theory is usually used to describe the characteristics of the average field and the turbulence field. However, Monin-Obukhov similarity theory is still used in many occasions. By acquiring the wind speed and temperature data at two different heights in a rough sublayer of Hefei city, China, the difference between the Monin-Obukhov similarity theory and the local similarity theory is analyzed. At the same time, the universal function of the normalized standard deviation of wind speed and temperature with the local atmospheric stability varying with height is also focused. The statistical results show that the friction speed u* at two heights differs by more than 13%, and the characteristic temperature T* differs by less than 2%. It is also shown that the universal function of wind speed and temperature of the local atmospheric stability in surface layer of the flat underlying surface can be adopted here, however, the fitting coefficients are not the same as those in surface layer of the flat underlying surface and different at two height. It shows that the location of this experiment has the characteristics of a general rough sublayer, which is quite different from the flat and uniform underlying surface near the ground layer.

To accurately predict the aerosol optical depth (AOD) of typical urban agglomerations in eastern China, based on MODIS data from 2010 to 2019, the spatial and temporal differences of AOD between Beijing-Tianjin-Hebei region, Yangtze River Delta and Pearl River Delta and within them were analyzed. The AOD prediction model based on the combination of wavelet transform and BP neural network was built to predict AOD in typical urban agglomerations. The results show that: 1) the peak value of aerosol concentration in all urban agglomerations occurs in summer, and the average AOD of Beijing-Tianjin-Hebei region is the highest, followed by Yangtze River Delta and Pearl River Delta. 2) the analysis of AOD influencing factors shows that GDP index, population density and temperature are positively correlated with AOD, while normalized difference vegetation index (NDVI), precipitation and wind speed are negatively correlated with AOD. 3) the mean absolute error(MAE) of AOD prediction results in each region is lower than 0.12, error is less than BP neural network and R2 is greater than 0.75, indicating that the model can effectively improve AOD prediction ability compared with BP neural network.

The black carbon (BC) aerosol data of Baoji City, China were continuously monitored online from February 4 to 26, 2019 using AE-31 Aethalometer in this work, and then combined with the data of PM2.5 mass concentration, wind speed and direction, the variation of BC mass concentration and its sources during the pollution in this region were investigated by cluster analysis. The results shows that the average mass concentration of BC during the observation period is 2.8 μg·m－3, ranging from 0.4 to 8.0 μg·m－3, the average mass concentration of PM2.5 is 119.9 μg·m－3, ranging from 17.3 to 221.9 μg·m－3, and the average mass concentrations of BC and PM2.5 during heavy pollution are 3.4 μg·m－3 and 176.4 μg·m－3, respectively. When the air quality is "good", the daily variation of BC mass concentration has obvious peak; when the air quality is "light pollution", the daily variation of BC mass concentration is "double peak and double valley" type; when the air quality is "moderate and heavy pollution", the daily variation of BC mass concentration shows a trend of low during the day and high at night. It is alsoshown that southeast and northeast wind directions have a strong influence on BC. Under gusty and non-gusty conditions, when the air quality is good, light, moderate and heavy pollution, the BC mass concentrations are 1.9 and 1.5 μg·m－3, 2.4 and 2.2 μg·m－3, 3.5 and 3.0 μg·m－3, 3.7 and 3.3 μg·m－3, respectively. It shows that the heavier the pollution, the greater the BC concentration, and the pollutants tend to accumulate under static wind conditions. Furthermore, backward trajectory clustering analysis shows that the air mass from the east of Baoji and the blocking effect of Qinling Mountains have a greater influence on the concentration of BC in Baoji.

Based on the ozone (O3) concentration data of 10 national control stations in Hefei City, China in 2019, the spatial and temporal distribution characteristics of O3 and the influence of meteorological factors were studied by using mathematical statistics and regression analysis. The results show that: (1) the hourly and monthly average concentration of O3 is unimodal, and the monthly average concentration of O3 reaches the peak in June. (2) The contribution rate of O3 in Dongpu reservoir and High Tech Zone to polluted weather is relatively high, and the contribution rate is more than 10%. (3) The stations with more times of exceeding the standard in 2019 are mainly located in Dongpu Reservoir and High Tech Zone, and appear in summer. (4) Temperature, relative humidity and total solar radiation are positively correlated with O3 concentration, and O3 concentration reaches the highest value when temperature is 30～35 °C, relative humidity is 40%～50% and total solar radiation is 800～1000 W·m－2. When the wind speed is 4～4.5 m·s－1, the exogenous transportation is strong and the O3 concentration is high. In addition, precipitation has the scavenging effect on O3 precursor, and the higher O3 concentration, the more obvious the removal effect of precipitation.

In view of the challenge that the National Ambient Air Quality Monitoring Station (NAAQMS) is not suitable for large area distribution due to its large volume and high cost, a miniature air quality monitoring system is developed to monitor the concentrations of CO, NO2, O3, SO2, PM2.5 and PM10 in atmosphere. Electrochemical gas sensors and optical particle counter are adopted to measure the concentration of air pollutants andparticles respectively in the system. Considering that the sensor is vulnerable to the influcence of temperature and humidity of atmosphere when measuring the concentration of pollutants, the measurement results are modified through the temperature and humidity compensation algorithm based on the multi-sensor fusion technology. Then the modified measurement results are compared with the data released by NAAQMS, and it is shown that there is a strong correlation between the two data. Compared with the data obtained from NAAQMS, the correlation coefficient for 10 days monitoring data obtained from the developled system is better than 0.7. After the algorithm correction, the correlation coefficient of some pollutants, such as PM2.5, can even be improved to 0.9. The air quality monitoring system is robust and small in size, which is suitable for long-term and large area distributed network monitoring of environmental air pollutants.

In order to achieve high-precision building information extraction, a rule-based object-oriented method is adopted, and a technical process of image preprocessing, multi-scale segmentation, construction of rule information, and feature extraction is proposed. Two sample areas in Yangzhou City, China (Jiajia Garden Community and Lianyi Nanyuan Community) based on the domestically produced GF-2 satellite are used for experimental validation of the method. It is shown that compared with the traditional method, the new method has better extraction effect and higher accuracy, with a recognition accuracy of 97.7% and a Kappa coefficient of 0.93.

An angle measurement system of a two-channel rotary transformer for spaceborne equipment is designed. For the purpose of obtaining high precision motor rotation angle value, the principle, error analysis, data combination algorithm and the software and hardware design of the angle measurement system are studied, and FPGA is used to detect and calculate the angular displacement of the stepping motor. In order to verify the accuracy of the designed two-channel angle measurement system, a Heidenhain photoelectric encoder with higher resolution is used to collect the data at the same time. By comparing the two data, it is shown that the error of the designed angle measurement system is within 30 ″, which meets the design accuracy requriements.