Expertise:

Air quality modeling Acid deposition modeling Atmospheric emergency response modeling Long-term soil acidification modeling

Honors:

Publication:

An Junling, Ying Li, Yong Chen, Jian Li, Yu Qu, Yujia Tang (2013) Enhancements of major aerosol components due to additional HONO sources in the North China Plain (NCP) and implications for visibility and haze, Advances in Atmospheric Sciences, 30(1): 57-66. Summary: The Weather Research and Forecasting/Chemistry model (WRF-Chem) was updated by including photoexcited nitrogen dioxide (NO2) molecules, heterogeneous reactions on aerosol surfaces, and direct emissions of nitrous acid (HONO) in the Carbon-Bond Mechanism Z (CBM-Z). Our results indicate that when the three additional HONO sources are included, WRF-Chem can reasonably reproduce the HONO observations. Heterogeneous reactions on aerosol surfaces are a key contributor to concentrations of HONO, nitrates, ammonium, and PM2.5 across the North China Plain. The three additional HONO sources produced a ~10?50% increase in monthly mean concentrations of nitrates and ammonium across large areas of the North China Plain. For the Bohai Bay, the largest hourly increases of nitrates exceeded 90%, of ammonium exceeded 80%, and of PM2.5 exceeded 40%, due to the three additional HONO sources. This implies that the three additional HONO sources can aggravate regional air pollution, further impair visibility, and enhance the incidence of haze in some industrialized regions with high emissions of NOx and particulate matter under favorable meteorological conditions. 　　An Junling, Weiling Xiang, Zhiwei Han, Kaitao Xiao, Zifa Wang, Xinhua Wang, Jianbin Wu, Pingzhong Yan, Jie Li, Yong Chen, Jian Li, Ying Li (2013) Validation of the Institute of Atmospheric Physics emergency response model with the meteorological towers measurements and SF6 diffusion and pool fire experiments, Atmospheric Environment, 81: 60-67. 　　Summary: The urban canopy layer parameterization (UCP), a successive bias correction method, an atmospheric dispersion module for denser-than-air releases, and the emission intensity of chemicals monitored by a Fourier-transform-infrared remote sensor were incorporated into the Institute of Atmospheric Physics emergency response model (IAPERM). IAPERM’s performance was tested in Beijing using the field data collected from a 325-m meteorological tower and sulfur hexafluoride diffusion and pool fire experiments. The results show that the IAPERM simulations of the vertical wind speeds in the urban canopy layer with the UCP perform much better than those with the Monin-Obukhov similarity parameterization scheme, and IAPERM could be a promising tool for passive and dense gas diffusion simulations or forecasts 　　An Junling, Weiling Xiang, Zhiwei Han, Yi Zheng, Zifa Wang, Xinhua Wang, Jianbin Wu, Pingzhong Yan, Jie Li, Yu Qu, Yong Chen, Jiawei Li (2011) An integrated mobile platform for monitoring and forecasting of emergency air pollution, China Environmental Science, 31(8): 1241-1247. 　　Summary: We have developed the first Chinese integrated mobile platform for monitoring and forecasting of emergency air pollution (IMF), which is composed of a monitoring system (e.g., a Fourier-transform-infrared remote sensor and a thermal infrared imaging analyzer), a prediction system (the Institute of Atmospheric Physics emergency response model (IAPERM)), and a database. The database includes hazardous chemicals, early warning indices, and fast-search algorithms in addition to the fundamental data. Screened wiring, seismic hardening, and lightning protection were also carefully considered. The IMF has provided an efficient platform for decision makers to deal with emergency air pollution accidents in a scientific and regularized way. Over 30-day (from July 5 to August 6, 2010) experiments at Yangfang Town, Changping District, Beijing indicate that stable and efficient is the integrated mobile system, which runs approximately 5 minutes from the beginning of monitoring a pool fire to issuing the emergency planning. The successive bias correction method included in the IAPERM can improve the forecasted meteorological fields and maximum forecasted concentrations of black carbon near the surface reasonably agree with observations. 　　An Junling, Wei Zhang, Yu Qu (2009) Impacts of a strong cold front on concentrations of HONO, HCHO, O3, and NO2 in the heavy traffic urban area of Beijing, Atmospheric Environment, 43: 3454-3459. 　　Summary: Much rain and strong winds caused by a cold front occurred in Beijing during the period of Sep. 27 to Oct. 4, 2004 and led to sharp drops in maximum and mean concentrations of HONO, HCHO, O3, and NO2, i.e., the maximum concentrations were reduced by 5.9, 21.3, 45.6, and 44.4 ppb, respectively, and the mean concentrations were decreased by 4.0, 5.5, 30.3, and 32.3 ppb, respectively. For daily HOx production rates HONO photolysis was the largest contributor and over 90% contributions were from photolysis of HONO and HCHO. 　　An Junling (2006) Ozone production efficiency in Beijing area with high NOx emissions, Acta Scientiae Circumstantiae, 26(4): 652-657. 　　Summary: A cold frontal system passed Beijing and caused strong winds and much rain in Beijing in Sep. 27 to Oct. 4, 2004. The ozone production rate (PO3) and ozone production efficiency (OPE) were calculated before and after the frontal system by a photochemical box model, constrained with observed concentrations of long-lived chemical species taken from the field experiment in the NOx heavily polluted urban area of Beijing. The results indicated OPE was within the range of 1.5~6.0, with an average of 3.0, and minor changes in the OPE were found before and after the frontal system. 　　An Junling, Hiromasa Ueda, Kazuhide Matsuda, Hisashi Hasome, Motokazu Iwata (2003) Simulated impacts of SO2 emissions from the Miyake Volcano on concentration and deposition of sulfur oxides in September and October of 2000, Atmospheric Environment, 37(22): 3039-3046. 　　Summary: A regional air quality Eulerian model was run for 2 months (September and October of 2000) with and without SO2 emissions from the Miyake volcano to investigate effects of the changes in the volcanic emissions on SO2 and sulfate concentrations and total sulfur deposition around the surrounding areas. Simulations indicate that emissions from the Miyake volcano lead to increases in SO2 and sulfate concentrations in the surrounding areas downwind in the PBL by up to 300% and 150%, respectively, and those in SO2 levels in the area found ~390 km north away from the Miyake site in the free troposphere (FTR) by up to 120%. Total sulfur deposition amounts per month are also increased by up to 300%. Daily SO2 concentrations in different model layers display strong variability (10–450%) at sites significantly influenced by the volcano. 　　An Junling, Hiromasa Ueda, Zifa Wang, Kazuhide Matsuda, Mizuo Kajino, Xinjin Cheng (2002) Simulations of monthly mean nitrate concentrations in precipitation, Atmospheric Environment, 36(26): 4159-4171. 　　Summary: Monthly mean nitrate concentrations in precipitation over East Asia (10–55°N, 75–155°E) in April, July, September, and December of 1999 were simulated by using a regional air quality Eulerian model (RAQM) with meteorological fields four times per day taken from National Centers for Environmental Prediction. The distribution of the nitrate concentration in precipitation depends significantly on the emission patterns of nitrogen oxides (NOx = NO + NO2) and volatile organic compounds (VOC) and seasonal precipitation variability. Highest concentrations are found in the industrialized regions, i.e., the coastal area of the Mainland of China, the Bay of the Huanghai Sea and the Bohai Sea, Korea, and Southern Japan. Long-range transport may cause elevated concentrations in remote areas downwind of the industrialized regions under favorable meteorological conditions, e.g., low precipitation. 　　An Junling, Ling Zhou, Meiyuan Huang, Hu Li, Tsunehiko Otoshi, Kazuhide Matsuda (2001) A literature review of uncertainties in studies of critical loads for acidic deposition, Water, Air and Soil Pollution, 130: 1205-1210. 　　Summary: Uncertainties in the assessment of critical loads for acidic deposition are caused by the choice of biological indicators (BI), critical chemical values (CCV), the current methods used to determine critical loads for an ecosystem, and deficient field data. This paper focuses on the present steady-state mass balance (SSMB) approach, dynamic models and the importance of changes in atmospheric base-cation deposition (BCD), particularly in China. It is argued that 1) for the SSMB approach much uncertainty may come from the choice of BI and the related CCV, and long-term and large-scale monitoring data on weathering rates and growth uptake are urgently needed, especially in China, 2) significant uncertainty may be caused by changes in BCD during SO2 emission controls, particularly in China, 3) constructing a mechanistic Al submodel may be a promising direction for dynamical models, and 4) the nutrient cycle in the vegetation through biogeochemical processes should be incorporated into dynamic models but the input requirements should be moderate for broad application considerations. 　　An Junling, Meiyuan Huang (2000) Impacts of uncertainties in base-cation deposition on the assessment of critical loads for acidic deposition, Journal of Environmental Science and Health, A35(10): 1915-1921. 　　Summary: Less attention has been paid to changes in the concentration and the deposition amounts of base cations. This has brought about great uncertainty in the determination of critical loads for acid deposition. The paper utilized a newly developed long-term soil acidification model (LTSAM), to simulate the effects of atmospheric base cations on the critical load of red earth in Wenzhou, Zhejiang Province. Results showed that great changes in atmospheric base-cation deposition decreased the critical load by 68%. This suggested that by only reducing sulfur deposition without considering changes in the atmospheric base-cation deposition, would substantially overestimate the critical load of soils. Therefore, more attention should be focused on changes in base cations during reductions of SO2 emissions, and the long-term monitoring of base cation deposition needs to be strengthened, especially in China. 　　An Junling, Meiyuan Huang (1999) Long-term soil acidification model (LTSAM) development and application for analyzing soil responses to acidic deposition, Water, Air and Soil Pollution, 110(3-4): 255-272. 　　Summary: A long-term soil acidification model (LTSAM) which can describe calcareous and noncalcareous soil responses to acidic deposition is developed based on the conservation of alkalinity and Ulrich buffer ranges. The model which considers nine major ions of atmospheric deposition, has focused on certain soil processes (weathering of carbonates, silicates, and aluminum (Al) oxides or hydroxides, cation exchange, anion retention, and CO2 solubility). The modelling results indicate that increase or decrease in atmospheric deposition of base cations and not only changes in deposition of sulfate and H+ must be considered in assessment of critical loads both for red earth and calcareous drab soil. 　　Li Ying, Junling An, and Ismail Gultepe (2014) Effects of additional HONO sources on visibility over the North China Plain, Advances in Atmospheric Sciences, doi: 10.1007/s00376-014-4019-1(in press). 　　Summary: The objective of the present study was to better understand the impacts of the additional sources of nitrous acid (HONO) on visibility, which is an aspect not considered in current air quality models. Simulations of HONO contributions to visibility over the North China Plain (NCP) during August 2007 using the fully coupled Weather Research and Forecasting/Chemistry (WRF/Chem) model were performed, including three additional HONO sources: (1) the reaction of photo-excited nitrogen dioxide with water vapor; (2) the NO2 heterogeneous reaction on aerosol surfaces; and (3) HONO emissions. When the additional HONO sources were included in the simulations, the visibility was occasionally decreased by 20%–30% (3–4 km) in local urban areas of the NCP. In urban areas, monthly-mean accumulation-mode number concentrations (AMNC) and surface concentrations of aerosols were enhanced by 15%–20% and 10%–20%, respectively. Overall, the results suggest that increases in concentrations of PM2.5, its hydrophilic components, and AMNC, are key factors for visibility degradation. A proposed conceptual model for the impacts of additional HONO sources on visibility also suggests that visibility estimation should consider the heterogeneous reaction on aerosol surfaces and the enhanced atmospheric oxidation capacity due to additional HONO sources, especially in areas with high mass concentrations of NOx and aerosols. 　　Li Ying, Junling An, Min Min, Wei Zhang, Feng Wang, Pinhua Xie (2011) Impacts of HONO sources on the air quality in Beijing, Tianjin and Hebei Province of China, Atmospheric Environment, 45(27): 4735-4744. 　　Summary: Incorporated into the WRF-Chem model are the three HONO sources, i.e., the reaction of photo-excited NO2 with water (NO2* chemistry), heterogeneous reactions on aerosol surfaces, and HONO emissions. Four case simulations were performed in Beijing, Tianjin, and Hebei Province (BTH region) in August of 2007. Results indicate that the NO2* chemistry yields 30-50 ppb enhancements in daily maximum 1-h surface O3 concentrations in major cities and 3-10 ppb increases in monthly-mean daily maximum 8-h surface O3 concentrations in most areas of the BTH region. Heterogeneous reactions on aerosol surfaces lead to 5-20 ppb decreases in monthly mean NOy (total reactive nitrogen-containing compounds) concentrations in major cities over the BTH region. Heterogeneous reactions and HONO emissions are the largest, and the second largest contributor, accounting for ~59% and 26% of simulated HONO concentrations, respectively. The three HONO sources produce enhancements in monthly-mean daytime (10:00-17:00) concentrations of NOy, NO2, HNO3, HONO, and HOx being -1 to -5 ppb, -1 to -3 ppb, -0.3 to 0.5 ppb, 20-50 ppt, and 1-3 ppt, respectively. Comparison with observations shows that inclusion of the three HONO sources into the WRF-Chem model can considerably improve HONO and O3 simulations in the BTH region. For HONO the mean, the normal mean bias, the root mean square error, and the correlation coefficient is greatly improved from 0.04 to 0.56 ppb, from -97% to -39%, from 1.10 ppb to 0.51 ppb, and from -0.56 to 0.86, respectively, by comparison with the gas chemical mechanism only considered in the WRF-Chem model. This suggests that the three important HONO sources be included in air quality models, particularly in the areas with high emissions of NOx and particulate matter. 　　Qu Yu, Junling An, Jian Li, Yong Chen, Ying Li, Xingang Liu, and Min Hu (2014) Effects of NOx and VOCs from five emission sources on summer surface O3 over the Beijing–Tianjin–Hebei Region, Advances in Atmospheric Sciences, 31(4): 787–800. 　　Summary: The impacts of emissions from industry, power plant, transportation, residential, and biogenic sources on daily maximum surface ozone (O3DM) over the Beijing–Tianjin–Hebei (BTH) region in North China in the summer of 2007 were examined in a modeling study. The modeling system consisted of the Weather Research and Forecasting (WRF) model and the photochemical dispersion model, CAMx. The factor separation technique was used to quantify the effect of individual emission source types and the synergistic interactions among two or more types. The industry, power plant, and transportation emission source types were found to be the most important in terms of their individual effects on O3DM. The key contributor to high surface O3 was power plant emissions, with a peak individual effect of 40 ppbv in the southwestern BTH area. The individual effect from the biogenic emission category was quite low. The synergistic effects from the combinations of each pair of anthropogenic emission types suppressed O3 formation, while the synergistic effects for combinations of three were favorable for O3 formation when the industrial and power plant emission source types coexisted. The quadruple synergistic effects were positive only with the combination of power plant, transportation, residential, and biogenic sources, while the quintuple synergistic effect showed only minor impacts on O3DM concentrations. These results suggested that the synergistic impacts among emission source types should be considered when formulating emission control strategies for O3 reduction. 　　Wang Feng, Junling An, Ying Li, Yujia Tang, Jian Lin, Yu Qu, Yong Chen, Bing Zhang, Jing Zhai (2014) Impacts of uncertainty in AVOC emissions on the summer ROx budget and ozone production rate in the three most rapidly-developing economic growth regions of China, Advances in Atmospheric Sciences, doi: 10.1007/s00376-014-3251-z (in press). 　　Summary: High levels of uncertainty in non-methane volatile organic compound (NMVOC) emissions in China could lead to significant variation in the budget of the sum of hydroxyl (OH) and peroxy (HO2, RO2) radicals (ROx = OH + HO2+ RO2) and the ozone production rate [P(O3)], but few studies have investigated this possibility, particularly with three-dimensional air quality models. We added diagnostic variables into the WRF-Chem model to assess the impact of the uncertainty in anthropogenic NMVOC (AVOC) emissions on the ROx budget and P(O3) in the Beijing–Tianjin–Hebei region, Yangtze River Delta, and Pearl River Delta of China. The WRF-Chem simulations were compared with satellite and ground observations, and previous observation-based model studies. Results indicated that 68% increases (decreases) in AVOC emissions produced 4–280% increases (2–80% decreases) in the concentrations of OH, HO2, and RO2 in the three regions, and resulted in 35–48% enhancements (26–39% reductions) in the primary ROx production and ?65% decreases (68–73% increases) of the P(O3) in Beijing, Shanghai, and Guangzhou. For the three cities, the two largest contributors to the ROx production rate were the reaction of O1D + H2O and photolysis of HCHO, acetaldehyde, and others; the reaction of OH + NO2 (71–85%) was the major ROx sink; the major contributor to P(O3) was the reaction of HO2 + NO (?65%). Our results showed that AVOC emissions in 2006 from Zhang et al. (2009) have been underestimated by ?68% in suburban areas and by >68% in urban areas, implying that daily and hourly concentrations of secondary organic aerosols and inorganic aerosols could be substantially underestimated, and cloud condensation nuclei could be underestimated whereas local and regional radiation was overestim

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