Abstract:An online tracer-tagged method coupled into a chemical transport model was described. Without the errors caused by the non-linear character of O3 photochemistry, the online tracer-tagged method can be used to estimate the contributions from the photochemistry over various regions to the total O3 concentrations in the targeted region in one simulation. To evaluate the results, taking the contributions from the photochemistry over the tagged northern and southern parts of China as an example, the online tracer-tagged method was compared with the revised sensitivity analysis. The comparison suggested that the online tracer-tagged method can reproduce the horizontal and vertical distributions of the contributions from two tagged regions to the O3 concentrations in East Asia, and also capture the typical heavy regional transport episode. This indicated the tracer-tagged method in this study can be used to quantitatively assess the impact of the regional transport on the tropospheric O3. The analysis also showed that the photochemistry in the southern and northern parts of China had a noticeable impact on O3 in East Asia, and varied with the seasons.

Abstract:The Nested Air Quality Prediction Modeling System (NAQPMS) has been applied to the routine air quality forecast in Beijing during the Olympic Games. Monte Carlo method is used to analyze the uncertainty of ozone simulation of NAQPMS during the Olympic Games, from 8 to 24 Aug 2008. Latin hypercube sampling has been used for multi-variables sampling, and 50 ensemble runs have been made with 154 parameter uncertainties being considered together. By the temporal average, the most important parameter to the surface ozone output uncertainty in Beijing is the local precursor emissions during the day time. Other important factors include NO2 photolysis coefficient, wind direction, precursor emissions from the surrounding areas of Beijing, and vertical diffusion coefficient. The wind direction and precursor emissions from the surrounding areas of Beijing have the greatest impact on the uncertainty of daytime ozone simulation at higher levels (above about 150 m). The main uncertainty factors in ozone simulation at night are local NOx emissions and vertical diffusion coefficient. Given the predefined input uncertainties, the average uncertainty of ozone simulation is 19 ppb, ranging from 2 ppb to 49 ppb.

Abstract:CBM-Z chemical mechanism was used to simulate ozone diurnal concentration at 325-m meteorological tower in the Institute of Atmospheric Physics, Chinese Academy of Sciences, and evaluated the influences of meteorological conditions, control measures, and precursors of ozone on concentration of surface ozone. The results show that CBM-Z chemical mechanism reproduces diurnal concentration of ozone, nitric oxide, and nitrogen dioxide at the 325-m meteorological tower during Beijing Olympics well, there are very similar meteorological conditions while local ozone episodes occur, Volatile Organic Compounds(VOCs) and nitrogen oxides emissions reduced through practicing environmental control measures, which induce apparent reduction of surface ozone concentration, and the key factors which affecting the concentration of ozone are VOCs and carbon monoxide.

Abstract:A very-short-range Interactive Prediction System (VIPS) has been set up and used at several important Olympic venues by Beijing Meteorological Bureau (BMB) during the 2008 Beijing Olympic and Paralympics Games. The application of this system played an important role in enhancing the capacity of weather services. Taking the weather services of Paralympics Games Opening Ceremony rehearsal as a case, this paper discuss the implementation of acquiring real-time monitoring, early-warning information, and other forecasting products which can be easily and rapidly analyzed onsite, and then timely and accurate weather forecast information based on GIS(Geographic Information System) can be generated for the command center in order to avoid or reduce the impact of severe weather like heavy rainfalls. This research provides an important experience and strategy for future major events as well as very-short-range forecasting operation.

Abstract:For the purpose of providing high temporal and spatial forecast for 2008 Olympic weather service, a new system named as Very-short-range Interactive Prediction System (VIPS) for weather warning making and dissemination was developed. The design，development, and function of VIPS system were introduced. Based on the opening concept, VIPS was developed using open source community resources like Java and OpenMap, and it is easy to migrate and upgrade. Also, it is possible to combine data from observations like regional Doppler Radar mosaic, automatic weather stations, lightning detection system, and forecasting products from radar echo extrapolation and storm cell tracking, together with 3 km resolution Numerical Weather Prediction (NWP) products with layered data technology support. VIPS can be used to help forecasters to review realtime weather information with the detail GIS(Geographic Information System) information as a background and make a rational composite analysis according to the data sources focusing on nowcasting warning issues. Forecasters can then make a warning based on the analysis. After circling the warning area, venue information can be easily extracted from GIS layer and then with the support of XML(eXtensible Markup Language) templates predefined, different kinds of warning and specified products (like webpage, PDF file, text file) can be generated according to users requirement. Effective actions can then be taken with combination of accuracy and specificity in time and space. VIPS system played a successful role in the 2008 Olympics weather service and was used as an operational platform after the Olympics.

Abstract:A comprehensive system was developed to meet the demand of the security guarding during the 2008 Beijing Olympic Games. In the system, meteorological models, namely, MM5 and RAMS6.0, and a poisonous Clouds Diffusion Model over complex terrain (CDM) were configured in a one-way off-line nested way. In the system, MM5 runs were performed in a real-time operational way with a horizontal resolution of 3 km, which took the output from a global scale model，that is T213 from the Chinese Meteorological Administration（CMA), as the initial and boundary conditions, and the output from MM5 was used to drive the RAMS6.0 runs to provide a 36-hour prediction with a horizontal resolution of 500〖CD*2〗1000 m. The wind and turbulent field outputs from RAMS6.0 were sequentially used to drive CDM runs, which can provide the prediction of the concentration field and the dose field of the chemical clouds. During the 2008 Beijing Olympic Games, the system was used to provide the scenario prediction results and the security target was set as the National Stadium (known as the Bird’s Nest), and the quantitative analysis of the hazard risk was performed based on the scenario prediction results.

Abstract:Using the air pollution and meteorological data in Beijing, weather charts from Korea Meteorological Administration (KMA) and NCEP reanalysis data, the characteristics of the air pollution of Particulate Matter with particle size below 10 μm (PM10) in Beijing and its cause of formation during the 2008 Olympic Games period (from July to September) are analyzed, types of synoptic situations are classified according to being or not helpful to dispersion of pollutants, and typical synoptic situations and meteorological conditions in PM10 air pollution episodes are studied. The results are that: 1) There were eight days with PM10 air pollution in Beijing during the whole period, including a persistent PM10 air pollution. But no PM10 air pollution occurred during the Olympic Games and Paralympic Games, which mainly resulted from more rainfall in August and September of 2008. 2) Synoptic situations not helpful to pollutants dispersion (e.g. south wind with low speed, high air temperature and relative humidity, and persistent vertical inversion in low layer) were frequent, but they did not cause typical PM10 air pollution by a possible reason of the pollution control measures. 3) Most PM10 air pollutions were related with northwestward-moving typhoon or tropical cyclone, which would block synoptic system influencing North China to move eastward.

Abstract:Back Propagation neural network model (BP model) was applied to the Olympic air quality forecasting. By using MATLAB neural network toolbox, assembled air quality modeling forecasting system was combined with nearly real-time observations to fit BP neural network forecasting results. The measurements were made from 7 July to 26 August 2008 in the Peking University Health Science Center. Using these data, the performance of the BP neural network results is assessed. The results show that BP neural network can significantly improve the simulation results, with the average error rate decreasing by 34.7% and the correlation coefficient increasing by 39%. The advantage of BP neural network is more obvious when the original simulation results are poor. The sensitivity experiment of BP neural network sample size indicates that the number of samples is not the decisive factor in deciding fitting effect, and the stability of mapping relationship in samples plays a crucial role in raising the effect of prediction.

Abstract:The effect of air pollution control in Beijing and its surrounding areas during the 2008 Beijing Olympic Games was evaluated by using the analysis of aerosols extinction vertical distribution (from lidar) and aerosol backward trajectory. The results indicated:1) In general，aerosol extinction coefficients decrease within various altitudes (notably below 600 m and within 1200－4000 m) in 2008 compared to trends in 2007. 2) Statistical analysis of the different types of the extinction coefficient showed that high pollutant concentrations in 2008 mainly occurred in the vicinity of the boundary layer confirming the decrease of the extinction coefficients near the ground. Description of the aerosols backward trajectory showed that the aerosols (mainly transported from Beijing surrounding areas) displayed the extinction coefficient decrease by about 18.1% below 400 m. This highlighted significant impact of air pollution control efficiency in the surrounding areas on the air quality improvement in Beijing.

Abstract:Monthly mean NO2 concentrations in both urban and suburban areas of Beijing generally decreased in August from 2002 to 2008, with a decreasing rate of about 10% during the first five years and nearly 40% in 2008. Based on sensitivity studies with a Nested Air Quality Prediction Modeling System(NAQPM/IAP), quantitative assessments of the impacts of weather conditions and pollutant controlling measures on decreases in NO2 concentrations were made during Beijing Olympic Games in 2008. The impact of area and point emission controlling measures on NO2 concentrations was compared. The results indicates that pollutant controlling measures play a key role in decreases in NO2 concentrations during Beijing Olympic Games while the August weather condition in 2008 is more favorable for dispersion and scavenging of air pollutants compared with that in 2006. Area emission controlling measures are more effective than point emission controlling measures for decreases in NO2 concentrations.

Abstract:Black Carbon (BC) concentration at the urban site was measured using Multi-Angle Absorption Photometer (MAAP, Model-5012) around 2008 Beijing Olympic Games, and its temporal variation pattern and controlling factors were investigated according to corresponding meteorological data and traffic controlling policy during and after the Olympic Games period. Frequency analysis indicates that BC concentration for peak frequency before implement of vehicles control policy (before 20 Jul) was 3.4 μg·m-3, and it enhanced to 3.9 μg·m-3 averagely during 20 Jul to 7 Aug. During the Olympic Games period, BC concentration declined to 2.5 μg·m-3, 31% lower than the value before the Olympic Games period. According to meteorological data, the increase of rainfall amount and frequency of northerly wind (from 24.1% to 38.8%) might play an important role in the decrease of BC concentration in Beijing urban area. Motor vehicles monitoring data at Jianxiang Bridge of the Badaling Expressway show that the traffic mount has declined by about 30% during the rushing hours of weekday, which might be another possible contribution to the decrease of BC concentration.

Abstract:A new air pollution emission inventory of Hebei Province during the 2008 Beijing Olympic Games is generated on the basis of previous Beijing real-time forecast emission inventory from Wang et al.(2006), considering updated emission data and pollution control measures. Then with the help of Nested Air Quality Prediction Model System(NAQPMS), regional air quality simulation is processed to evaluate the updated pollution intensity and its effect. After comprehensive comparison between model outputs and measurements such as ground observation and satellite data from space, it is confirmed that the update efforts are resultful to some extent, especially on some primary species such as SO2. And a series of pollution control policies are believed to make a crucial contribution, shown by scenario analysis, to the air quality improvement during the Beijing Olympics.

Abstract:With the meteorological and contaminated information from Beijing 325m meteorological tower in the Institute of Atmospheric Physics, Chinese Academy of Sciences, and the gas dry deposition resistance model, the influencing factors of the dry deposition，the dry deposition rate，and the dry deposition flux in Beijing before and during the Beijing Olympic Games were calculated. The results show: 1）With the variations of the stability，the solar radiation intensity，and the style of the surface, the SO2 and NO2 dry deposition rates change obviously, and the apparent resistance is the main factor impacting the dry deposition rate. 2）The dry deposition rate and flux during the daytime are greater than those during the nighttime. 3）The dry deposition can remove 24 t SO2 and 55.2 t NO2 in Beijing area in one day before the Beijing Olympic Games, and can remove 10.8 t SO2 and 50.4 t NO2 in one day during the Beijing Olympic Games. This means that the emission reduction measures taken by the Chinese government during the Olympic Games have had a significant effect.

Abstract:RAMS-CMAQ, a coupled regional air quality modeling system, is used to analyze the temporal and spatia1 variations of the surface O3 concentration over Beijing and its surrounding areas in August 2008． The result indicates that the model can generally reproduce the main observational feature of O3 and the wind，and the pollution control can reduce the O3 concentration noticeably. On the other hand, analysis of the formation of high O3 concentration indicates that the O3 concentration would be high under the favorable weather condition, for example, on both 2 August and 24 August, when there is convergence in a weak wind field or the southerly wind transports air pollutions. The impact of the pollution control in August is better in the surrounding areas than in the urban districts of Beijing.

Abstract:An investigation of PM10(the synoptic patten and particle matter less than 10 μm) transport variation before and after Beijing Olympics (20 Jul to 24 Aug 2008) was performed through fluxes simulation carried on the Nested Air Quality Prediction Modeling System (NAQPMS). Results showed large magnitude and distribution variations of PM10 fluxes, essentially southerly, southeasterly, and easterly, due to changes in meteorological conditions. Before the Olympics opening ceremony, the most important fluxes transported into Beijing were southerly (55.8%) and southeasterly (29.4%) versus significant changes in a range of 38.1% and 47% respectively during the Olympic games (8－24 Aug 2008) with significant decrease of total flux from 50 t·h-1 to 40.2 t·h-1. Vertically, the strongest PM10 transport occurred in the lower boundary layer before 8 Aug, while an almost homogeneous transport prevailed during the Olympics games. An in-deep analysis was performed on the impact of meteorology and emissions on PM10 transport and air quality over Beijing through substitution between 2006 and 2008 emissions data in NAQPMS model, proved that, in sight of the important role meteorological conditions played in regional PM10 transport, emissions control (environmental restrictions) during the Olympic Games was more effective in improving air quality over Beijing.

Abstract:The Nested Air Quality Prediction Model System (NAQPMS) coupled with an on-line pollutant source tracking module is utilized to estimate the contributions of the air pollutants，i.e., SO2 and PM10，from Beijing and its surrounding areas to urban Beijing under the air quality assurance program for Beijing Olympic Games quantitatively. The results indicate that: 1) The contribution of the local emissions of Beijing is predominant in the SO2 and PM10 concentration in all counties except Pinggu County, especially in urban Beijing, where the contribution of Beijing emissions exceeds 80% of the SO2 and PM10 concentrations. 2) Under the pollutant control measures in the air quality assurance program, the contribution of Beijing emissions to the SO2 concentration in urban Beijing reduced significantly, and that of the surrounding areas(Tianjin and Hebei) to SO2 concentration had a slight decline, thus, the SO2 concentration in urban Beijing decreased significantly, but the contribution per unit emission of Beijing local emissions increased. 3) The contribution of Beijing emission to primary PM10 concentration in urban Beijing decreased significantly while the surrounding contributions had a slight increase, and therefore the PM10 concentration also decreased under the air quality assurance program.

Abstract:Using the precipitation data in Beijing during 1961－2007, statisitcs rate of the climatic tendency, polynomial curve fitting, and Morlet wavelet method, the climatic characteristics and the trends of the climatic change of rainstroms in Beijing were analysed. The results show that: 1）Rainstorm has obvious monthly variation characteristics, the first 10 days of August(before and after the Beijing Olympic Games opening ceremony)are the most evident stage of the rainstorm days in Beijing. 2）The general trend of the annual rainstorm days has slowly decreased with fluctuation in Beijing during 1961〖CD*2〗2007, the descending rate of the annual rainstorm days at Shahe station is the slightest, that at the Xijiao station is second, and that at Nanyuan station is the most marked among the three stations. 3）The variations of the incremental and reduced rainstorm days have periodic characteristics, and there are absolutely opposite variation trends at Nanyuan station before 1990, in comparison with Shahe station and Xijiao station. 4）The variations of the annual rainstorm days have multiple periodicity in Beijing. Different periodic oscillations of the annual rainstorm days exist at Nanyuan station, Shahe station, and Xijiao station.

Abstract:Monte Carlo ensemble forecast method is employed to establish a surface ozone ensemble forecast system in Beijing. The ensemble forecast system is constituted by 50 forecast members with 154 model input parameters of Nesting Air Quality Prediction Model System (NAQPMS) perturbed. The forecast skill of the surface ozone ensemble forecast system is evaluated over three days’forecast (11－13 Aug 2008) during Beijing Olympics 2008. Analysis is performed on probabilistic forecast skill, deterministic forecast skill and on how to represent forecast uncertainty. Results indicate that, compared with single model, ensemble forecast significantly improves accuracy of ozone hourly concentration and daily maximum prediction. By selecting sub-ensemble with smaller error, the root mean square error of forecast is reduced by over 10%.

Abstract:A continuous heavy fog process and air pollution occurred in East China during 7〖CD*2〗11 January 2008. Based on the synoptic data, NCEP/NCAR reanalysis data set and MM5 model outputs, the surface circulation, water vapor condition, dynamic factor, temperature stratification, and air quality are analyzed in detail. It is concluded that the surface moisture flux divergence, vertical velocity, and the divergence difference between 1000 hPa and 500 hPa are not significantly correlative with the visibility, while the relative humidity near the surface is significantly negatively correlative, the temperature lapse rate（γ）near the surface is significantly positively correlative with the visibility, therefore, RH≥85%、γ＜0.2 ℃·（100 m）-1 could be regarded as the necessary conditions of fog formation. In addition, the lowest visibility in Shanghai Hongqiao International Airport during the period of 0400 UTC on the previous day to intraday 0300 UTC is intensely negatively correlative with the Air Pollution Index （API） in the meantime. The API rising up to 150 could be an important criterion of fog formation in Shanghai Hongqiao International Airport.

Abstract:A heavy pollution case in December 2006 in Lanzhou was simulated using the Nested Air Quality Prediction Model System (NAQPMS). The diurnal variations of the air pollutants and its mechanism were discussed. The results showed that NAQPMS can reproduce the temporal and spatial variations of the air pollution under complex terrain conditions. The concentrations of the pollutants presented a pattern with daytime maximum and night minimum, which can be explained by the daytime nearsurface temperature inversion layer.