[Characteristics of Ozone Concentration in Shanghai and Its Associated Atmospheric Circulation Background During Summer Half-years from 2006 to 2021].

It is of great importance to scientifically evaluate the impact of weather and climate conditions on the occurrence of O3 pollution in order to improve the accuracy of O3 pollution forecasts， as well as to reasonably control and reduce the adverse effects of O3 pollution. The characteristics of O3 concentration and climate background were analyzed based on daily O3 concentration data， meteorological factors， and NCEP/NCER reanalysis data from 2006 to 2021 in Shanghai. In addition， the differences in atmospheric circulation situations during years with anomalous O3 concentrations were compared and diagnosed from the perspective of climatology. Additionally， the monthly O3 concentration prediction model （seasonal autoregressive integrated moving average with exogenous regressors， SARIMAX） was further established by adding the key meteorological factors. The results indicated that both the whole-year average and summer half-year average O3 concentrations in Shanghai were increasing with fluctuation， and the summer half-year average was much higher than the annual average， up to 36.2%. Furthermore， there was a significant negative correlation between O3 concentration and wind speed （correlation coefficient of -0.826） and a significant positive correlation with the frequency of static wind and the number of days in which the low cloud cover was less than 20% （correlation coefficients of 0.836 and 0.724， respectively）. The monthly mean O3 concentration had a clear periodicity， showing a pattern with a high concentration in the middle period （April to September） and a low concentration at the beginning and end of the periods. High O3 concentration years （2013-2021） were accompanied by more polluted days， lower average wind speed， more small wind （≤1.5 m·s-1） days， more days of low cloud cover of less than 20%， more days of high temperature， higher direct solar radiation， and more sunshine hours. When the location of the stronger West Pacific subtropical high was westward and southward in the summer half-year， Shanghai was influenced by an anomalous westerly wind， which was not conducive to the transportation of clean air from the sea to Shanghai and thus led to the high concentration of O3 pollution. When the long wave radiation emitted from the ground was low in the summer half-year， it was favorable for the increase in ground temperature and caused a high concentration of O3 pollution. Adding direct solar radiation， maximum temperature， and wind speed as exogenous variables to the monthly O3 forecast model could significantly improve the effectiveness of the monthly forecast， with the root mean square error decreasing by 47.7% （from 22 to 11.5） and the correlation coefficient increasing by 11.2% （from 0.819 to 0.911）， which could be applied to the practical prediction of monthly O3 concentration.

[A Comparison Study on Multiple Modeling Approaches for Air Pollutant Geographic Model Development in Shanghai].

Geostatistical models have been widely used in the exposure assessment of ambient air pollutants. However, few studies have focused on comparisons of modeling approaches and their prediction results. Here, we collected the NO2 and PM2.5 monitoring data from 55 sites in Shanghai from 2016 to 2019 and the geographic variables, such as road network, points of interest of emission locations, and satellite data were included. We used partial least squares regression (PLS), supervised linear regression (SLR), and random forest (RF) algorithms to develop spatial models and used ordinary kriging (OK) to develop a two-step model. We evaluated the models using a 5-fold cross validation method and selected the best model structure for each modeling approach between one-or two-step models that had been developed with or without OK. The results revealed that the best NO2 models were the RF-OK (Rmse2 was 0.70-0.82) and PLS-OK (Rmse2 was 0.78-0.84) models; the PLS model for PM2.5(Rmse2 was 0.62-0.71) outperformed the other PM2.5 models. We used the best models to predict annual exposures in Shanghai at a 1 km spatial scale and conducted the correlation analysis among the predictions of the best models. The results demonstrated that the NO2 predictions had higher correlation coefficients (r was 0.82-0.91) compared with those of the PM2.5 models (r was 0.66-0.96). Based on the exposure results predicted using the three models in 2019, we evaluated the cumulative population exposure concentrations for NO2 and PM2.5 in Shanghai.

Study on Tungsten Metallization and Interfacial Bonding of Silicon Nitride High-Temperature Co-Fired Ceramic Substrates.

For the first time, Si3N4 HTCC has been prepared using W as the metal phase by high-temperature co-firing (1830 °C/600 KPa/2 h) as a potential substrate candidate in electronic applications. It was discovered that the addition of Si3N4 to the W paste has a significant impact on thermal expansion coefficient matching and dissolution wetting. As the Si3N4 content increased from 0 to 27.23 vol%, the adhesion strength of W increased continuously from 2.83 kgf/mm2 to 7.04 kgf/mm2. The interfacial bonding of the Si3N4 ceramic and the conduction layer was discussed. SEM analysis confirmed that the interface between Si3N4 and W exhibited an interlocking structure. TEM, HRTEM and XRD indicated the formation of W2C and W5Si3 due to the interface reactions of W with residual carbon and Si3N4, respectively, which contributed to the reactive wetting and good adhesion strength between the interface. Suitable amounts of Si3N4 powder and great interfacial bonding were the main reasons for the tough interfacial matching between the Si3N4 ceramic and the conduction layer.

[Changes and Potential Sources of Atmospheric Black Carbon Concentration in Shanghai over the Past 40 Years Based on MERRA-2 Reanalysis Data].

As an important component of atmospheric aerosols, black carbon (BC) has a great influence on the regional and global radiation balance, climate, and human health due to its small particle size, large specific surface area, and radiative forcing potential. Here, the spatio-temporal characteristics of atmospheric BC were investigated based on modern-era retrospective analysis for research and applications version 2 (MERRA-2) reanalysis data and ground observation data during 1980-2019 in Shanghai, a highly urbanized city in mainland China. The influences of local emissions and regional transmission on regional-scale BC concentrations were examined using the M-K trend test, backward trajectory analysis, and the potential source contribution function (PSCF). The results showed that:① MERRA-2 BC and ground observation datasets showed good consistency (R∈[0.68, 0.72]), indicating that MERRA-2 reanalysis data can be used to reveal long-term changes in ground-level atmospheric BC concentrations; ② Atmospheric BC concentrations in Shanghai over the past 40 years can be divided into three stages:a "low value" stage of slow growth[1980-1986, (1.75±0.17) µg·m-3], a relatively stable "median value" stage[1987-1999, (2.18 ±0.07) µg·m-3], and a fluctuating "high value" stage[2000-2019, (3.07±0.31) µg·m-3]. Seasonally, Shanghai's BC concentrations generally show a "U" pattern with low concentrations in summer and high concentrations in winter. As a result of black carbon emissions from marine diesel engines and other engines used for water transportation, a small peak also occurs in July; ③ The diagnostic quality ratio of air pollutants and the bivariate correlation analysis[R(BC-NO2)>R(BC-CO)>R(BC-SO2)] indicated that traffic emissions were the main sources of atmospheric BC in Shanghai, especially by heavy diesel vehicles; ④ The backward trajectory and PSCF analyses found that the air mass of Shanghai in summer was dominated by a clean sea breeze, accounting for 77.18%. In contrast, during the other seasons, more than 50% of the air mass came from the north. The potential source regions of atmospheric BC in Shanghai are mainly distributed in eastern China, expanding outwards and centering on the Yangtze River Delta, and the expansion direction is consistent with the directions of the backward trajectories.

[Characteristics of Aerosol Particulate Concentrations and Their Climate Background in Shanghai During 2007-2016].

We use daily aerosol particulate matter<10 µm (PM10) concentration data from 2006 to 2016 in Shanghai along with meteorological elements (wind and temperature), atmospheric stability, temperature inversion, and upper atmosphere circulation data, to analyze the variation characteristics of the PM10 concentrations and differences of the winter climate background. We establish a multivariate linear stepwise regression equation, and also compare and analyze differences in the upper atmospheric circulation by selecting the years with the highest and lowest PM10 concentrations. The results showed an oscillating downward trend in the annual average concentrations of PM10 in Shanghai, whereas seasonally, PM10 concentrations were relatively high in winter and showed two peaks with a low in between. PM10 concentrations were negatively correlated with the daily average wind speed and the daily mixing layer height at 20:00, and positively correlated with the frequency of northwest wind, the mean daily temperature, and the frequency of stable weathers and thermal inversion at 20:00. When the 500 hPa height field in the northern part of China was a positive anomaly in winter, a warm winter prevailed and led to high PM10 concentrations. When the 500 hPa height field was a negative anomaly, cold air frequently moved southward to result in relatively low temperatures, which caused relatively low PM10 concentrations. When the wind field at 850 hPa was easterly, the wind speed was relatively large and resulted in relatively low PM10 concentrations.

[First Long-Term Study of Atmospheric New Particle Formation in the Suburb of Shanghai from 2015 to 2017].

In this study, long-term continuous monitoring of atmospheric new particle formation was conducted from 2015 to 2017 in the Shanghai suburbs using a scanning mobility particle sizer (SMPS). Combined with meteorological parameters, gaseous pollutants, and PM2.5 chemical composition data, the characterization of new particle formation was analyzed. The results of data analysis showed there were 172 new particle formation (NPF) days in the Shanghai suburbs, accounting for 18.3% of the total effective days (942 d). Typical new particle formation days (Event) and new particle growth-shrinkage (Shrinkage) days were 150 d and 32 d, respectively. The frequency of NPF occurrence was the highest in spring and summer, followed by autumn and winter. Compared with non-new particle formation (Non-NPF) days, Event and Shrinkage days had higher temperature and wind speed, lower humidity, less rainfall, and stronger solar radiation. The ratio of Event days was the highest when the prevailing wind was southerly, southwesterly, or westerly, and when the air masses were mainly from the vegetation cover and agricultural planting areas in the Taihu Lake Basin. The prevailing wind directions for Non-NPF and Shrinkage days were northeasterly and easterly to southeasterly. On the Event days, SO2 and O3 were higher than that on the Non-NPF days, indicating gaseous sulfuric acid and photochemical reactions were key contributors to new particle formation. Higher PM10 concentration was detected on the Event days than on the Non-NPF days, which may be attributed to the photocatalytic reaction. All the pollutant concentrations were the lowest on Shrinkage days, except that of O3. The average concentrations of inorganic components of PM2.5, such as NH4+, SO42-, and NO3- were higher on Event than on Non-NPF days in fall, whereas the opposite results were observed in other seasons. The average concentration of organic carbon on Event days was higher than that on Non-NPF days in each season. The concentrations of PM2.5 components on Shrinkage days were the lowest. However, the ratio of organic carbon on Shrinkage days was higher than that on Non-NPF days in spring, summer, and winter. The higher ratio of organic carbon on the NPF days than on the Non-NPF days suggested an important role of organic matter in the formation and growth of new particles in the suburbs of Shanghai.

[Characteristics and sources of organic carbon and elemental carbon in PM2.5 in Shanghai urban area].

Organic carbon (OC) and elemental carbon (EC) in PM2.5 samples collected in Shanghai urban area during June 2010 to May 2011 were analyzed with IMPROVE-TOR protocol. The results showed that the annual average concentrations of OC and EC in PM2.5 were 8.6 µg.m-3 ± 6.2 µg.m-3 and 2.4 µg.m-3 ± 1.3 µg.m-3 respectively, accounting for 20% of PM2.5 mass concentration. The seasonal average concentrations of OC and EC were highest in winter and lowest in summer. And the percentages of OC and EC in PM2.5 were highest in autumn. The annual average OC/EC ratio was 3. 54 ± 1. 14. The concentrations of secondary organic carbon (SOC) were evaluated by the minimum OC/EC ratio method and the annual average concentration of SOC was 3.9 µg.m(-3) ±4.2 µg.m(-3), accounting for 38.9% of OC. In summer, the concentrations of SOC were relatively low and were correlated well with the maximum hourly concentrations of ozone, which indicated that the photochemical reaction was an important way of SOC formation. In autumn and winter when the west wind direction was predominant, the concentrations of SOC were higher than that in windless condition, which meant the transportation of SOC. The carbonaceous components were associated with source contributions using the principal component analysis (PCA) with eight thermally-derived carbon fractions, OC1, OC2, OC3, OC4, EC1, EC2, EC3 and OPC. Motor vehicle, coal-fired units, biomass burning and road dust were four main sources of OC and EC in PM2.5 in Shanghai urban area, which contributing 69. 8% - 81. 4% of carbonaceous aerosols. The contribution of motor vehicle was high throughout the year. Biomass burning contributed about 15% -20% of OC and EC. The influence of road dust was relatively obvious in spring and autumn. And the contribution of coal-fired units was higher in winter than those in other seasons.

[Secondary aerosol formation through photochemical reactions estimated by using air quality monitoring data in the downtown of Pudong, Shanghai].

Analyses of diurnal patterns of PM10 in the downtown of Pudong, Shanghai have been performed in this study at different daily ozone maximum concentrations (O(3,max)) from May to October, 2010. In order to evaluate secondary aerosol formation at different ozone levels, CO was used as a tracer for primary aerosol, and 0(3, max) was used as an index for photochemical activity. Results show that along with increasing of O3 concentration, the concentration of primary and secondary aerosol was increased respectively from 0. 036 to 0.044 mg x m(-3) and from 0.018 to 0.055 mg x m(-3). The ratio of secondary to primary aerosol was increased from 49.8% to 124.5%. Furthermore, along with the increase of O(3, max) the forming time of O(3,max) and secondary aerosol was changed respectively from 13:00 to 14:00 and from 11:00-20:00 to 09:00-20:00. At the same time, the chemical composition of PM2.5 was different at different photochemical levels. PM(2.5) was composed of 12.0% organic carbon (OC), 18.7% sulfate (SO4(2-1)), 13.1% nitrate (NO3-) and 4.5% element carbon (EC) when O(3, max) was < 0.10 mg x m(-3) and PM2.5 was composed of 20.0% organic carbon (OC), 22.9% sulfate, 23.1% nitrate and 4.7% element carbon (EC) with O(3, max) > 0. 20 mg x m(-3). These results approved that the photochemical reactivity promoted the production of SO4(2-), NO3- and OC.

[Correlation analysis between the PM2.5, PM10 which were taken in the hazy day and the number of outpatient about breathing sections, breathing sections of pediatrics in Shanghai].

In order to explore the correlation between the concentration of PM10, PM2.5 which were taken during the day of haze pollution and the average number of outpatient service, pediatrics. Based on the date with the number of pediatric outpatient and the concentration of PM2.5, PM10 which were taken form the haze days on 1 January 2009 - December 31 in 6 hospital in shanghai such as xinhuan hospital, we analyzed the data and executed the risk evaluation. The results showed that: in the haze day, when the average concentration of PM10 increase 50 microg/m3, the average number of the outpatient service and pediatric clinic increased 3% and 0.5%, when the average concentration of PM2.5 increase 34 microg/m3, the average number of the outpatient service and pediatric clinic increased 1.9% and 3.2%, Also, the pollution of PM10 and PM2.5 has a larger cumulative effects on the number of outpatient service. And the accumulation effect will be To maximize after 6 days behind the haze pollution. Thus, PM2.5, PM10 which were taken during the haze of pollution in shanghai, has certain influence on the average number of outpatient service, pediatric clinic.

[Characteristics of ambient VOCs and their role in O3 formation: a typical air pollution episode in Shanghai urban area].

The concentration, speciation and chemical reactivity of ambient volatile organic compounds (VOCs) in shanghai city were analyzed and measured by using online gas chromatography with flame ionization detection systems (GC-FID) during a typical air pollution episode (from Oct. 30th to Nov. 2nd, 2010) and 55 kinds of VOCs were detected. The results show that averaged concentrations of VOCs was 27 x 10(-9) before the episode, and then dramatically increased by 3 times (87 x 10(-9)) in the episode than the former, the main components were alkanes (35.2 x 10(-9)), aromatics (30.0 x 10(-9)), alkenes (21.6 x 10(-9)). Furthermore, the maximum ozone formation potential (PhiOFP) is analyzed and showed that PhiOFP (in the episode) > PhiOFP (after the episode) PhiOFP (before the episode). Before the episode, the percent of PhiOFP for aromatics 53.0% , alkenes 36. 1% and alkanes 11.7%; in the episode, the percent of PhiOFP for aromatics 54.7%, alkenes 36.7% and alkanes 9.8%; after the episode, the percent of PhiOFP for alkenes 52.7%, aromatics 36.0% and alkanes 13.2%. Alkenes (C2-C4) and aromatics (C6-C8) are the main components for the ozone formation, namely toluene, m,p-xylene, 1,3-butadiene, propene, ethene et al. In addition, the relationship is negative and nonlinear between the O3 and PhiOFP. And efficiencies of PhiOFP formed into O3 are below 20. 0% in different stage of episode. This is very important and meaningful for the quantitative evaluate the influence of VOCs towards O3.