Unique characteristics of regional and urban ozone formation in China
Economic growth and associated pollution emissions in China are concentrated over three connected plains
to the east. The convergence of pollutant emissions and population over the vast stretch of the geographically
flat plains of East China makes the region susceptible to high-ozone exposure. We applied a regional
chemical transport model (REAM) to simulate an episode of highly elevated ozone over East China on June 9-
14, 2004. During this episode, the East China plains are under a high pressure system, which suppresses the
ventilation of pollutants from the boundary layer. Simulated ozone concentrations over a major fraction of East
China reach high levels, all the way down to the Pearl River Delta region in the southern border. Model results
indicate that controlling anthropogenic NOx emissions effectively reduces the area with high-ozone exposure.
We also analyzed the full suite of atmospheric pollutants measured at on a building roof top in Peking
University during the summer CAREBEIJING Experiment (August, 2007). A 1-D photochemical model is
applied to analyze these measurements. Observed concentrations of PAN and HNO2 are much higher than
expected from the model. Large amount of methylglyoxal appears to play a key role in the formation of PAN. The
high abundances of PAN and HNO2 indicate that oxidant levels are much higher than simulated in standard
photochemical models; the high oxidant levels have significant ramifications on ozone formation and the
effectiveness of emission control in Beijing.
Pollution, Climate and Their Potential Interactions in China
As the largest, most populated and fastest developing country of the world, China is most susceptible to
pollution and climate changes. Some preliminary model studies have implied significant effects, but few of the
studies were founded on actual observational data. By modulating atmospheric heating profile, surface energy
balance and cloud microphysics, atmospheric pollutants, especially aerosols (particle pollutants) have been
hypothesized to interact with the Asian monsoon system and play a significant role in observed changes in
precipitation, temperature and atmospheric circulation. Testing the hypotheses requires extensive and reliable
measurements concerning their properties, radiative fluxes, cloud microphysics, precipitation, and other
atmospheric variables, which is the primary goal of two major ongoing field campaigns conducted before,
during and after the Beijing Olympic Games under the East Asian Study of Tropospheric Aerosols: an
International Regional Experiment (EAST-AIRE) and the ARM Mobile Facility deployment in China (AMF-China).
In my talk, I will review the status of the two observation campaigns; present some preliminary findings;
elaborate the potential usage of the data in dealing with the aforementioned issues.
Measurements of Volatile Organic Compounds and Gaseous Sulfuric Acid During the 2008 CAREBEIJING Campaign
Air quality in Beijing has been a hot topic recently, because Beijing hosted the 2008 summer Olympics. To combat the problem, China ordered numerous factories shut down or used only sporadically during the games to limit air pollution in the area. Another major step involved ordering about one-half of the city's 3.3 million vehicles off the road during the games, allowing only cars on roads with odd or even-numbered license plates on alternate days until the games were over. In addition, China has implemented new auto emission standards since March 2009 with regulations that are similar to those used throughout Europe. Our team at the Texas A&M participated in the 2008 CAREBEIJING campaign, with the objectives of studying the complex chemistry of the air in Beijing, looking at emission controls and their effectiveness, studying the surrounding air from other regions and how it can affect Beijing's air, and comparing all of our findings with air quality in other cities we have examined, such as Mexico City and Houston. In this talk, preliminary results of measurements of volatile organic compounds (VOCs) and gaseous sulfuric acid will be presented to discuss the trends of VOCs and new particle formation associated with the traffic control.
Measurement of Urban Air Quality by an Open-Path Quantum Cascade Laser Absorption Spectrometer in Beijing During Summer 2008
The 2008 Olympic Games focused attention on the air quality of Beijing, China and served as an important test-bed for developing, deploying, and testing new technologies for analysis of air quality and regional climate in urban environments. Poor air quality in urban locations has a significant detrimental effect on the health of residents while also impacting both regional and global climate change. As a result, there exists a great need for highly sensitive trace gas sensors for studying the atmosphere of the urban environment. Open-path remote sensors are of particular interest as they can obtain data on spatial scales similar to those used in regional climate models. Quantum cascade lasers (QCLs) can be designed for operation in the mid-infrared (mid-IR) with a central wavelength anywhere between 3 to 24 μm and made tunable over a wavelength interval of over 0.1 μm. The Quantum Cascade Laser Open-Path System (QCLOPS) is a mid-infrared laser absorption spectrometer that uses a tunable, thermoelectrically cooled, pulsed Daylight Solutions Inc. QCL for measurement of trace gases. The system is aimed at applications with path lengths ranging from approximately 0.1 to 1.0 km. The system is designed to continuously monitor multiple trace gases [water vapor (H2O), ozone (O3), ammonia (NH3), and carbon dioxide (CO2)] in the lower atmosphere. A field campaign from July to September 2008 in Beijing used QCLOPS to study trace gas concentrations before, during, and after the Olympic Games in an effort to capture changes induced by emissions reduction methods. QCLOPS was deployed at the Institute of Atmospheric Physics - Chinese Academy of Sciences on the roof of a two-story building, at an approximate distance of 2 miles from the Olympic National Stadium ("The Bird's Nest.") QCLOPS operated with an open-path round trip distance of approximately 75 m. The system ran with minimal human interference, twenty-four hours per day for the full campaign period. In order to collect data over numerous absorption peaks belonging to the target gases of H2O, NH3, O3, and CO2, measurements were made at 317 different wavelengths within the full tuning range of the laser (1020 - 1070 cm-1). We present the design of this novel sensor which was successfully built, deployed, and operated with minimal operator intervention for the three month field campaign period. Furthermore, we present the results of the field campaign and the capabilities of the QCLOPS system to measure fluctuations of the trace gases at parts-per-billion levels. The time series data illustrate the changing levels of the trace gases over the campaign period. In addition, data from commercial sensors simultaneously deployed at the field site are presented as a validation of the capabilities of the QCLOPS system. This work was supported by MIRTHE (NSF-ERC #EEC-0540832).
Atmospheric Particulate Matter Pollution During The 2008 Beijing Olympics
To assess the particulate matter (PM) pollution during the 2008 Beijing Olympic games, size fractionated PM samples of >PM10, PM2.5-PM10, and <PM2.5 were collected at Peking University in Northwestern Beijing for a 2 week time period prior to the Olympics, during the 2 week period of the Olympics, and for a 4 week time period following the Olympics. These time periods included 6 weeks with source control and 2 weeks without source control measures. Our SumPM10 (PM2.5-PM10 + <PM2.5) concentrations were a factor of 1.3 times higher than the Beijing Environmental Protection Bureau's PM10 concentrations at near-by sites. The mean <PM2.5 and SumPM10 concentrations were 64.7 ± 36.3 μg/ m3 and 82.4 ± 42.4 μg/ m3 during the Olympic time period and 93.9 ± 50.2 μg/ m3 and 124.5 ± 65.8 μg/ m3 outside of the Olympic time period, respectively, and were statistically different between the two time periods. In addition, the mean <PM2.5 and SumPM10 concentrations were 81.3 ± 43.2 μg/m3 and 105.3 ± 52.4 μg/ m3 during the source control time periods and 97.2 ± 59.8 μg/ m3 and 132.2 ± 83.8 μg/ m3 outside of the source control time periods, respectively, but were not statistically different. The PM2.5 concentrations accounted for 62% to 86% of the SumPM10 concentrations throughout the sampling time periods. In addition, air mass back trajectory analysis indicated that high PM concentration in Beijing were attributed to source regions located south of Beijing, including Tianjin municipality and Hebei, Shanxi and Shandong provinces, while low PM concentration in Beijing were attributed to source regions located Northwest of Beijing, including Russia and Mongolia. While meteorological parameters (air masses from the south and precipitation) accounted for 40% of the total variation in SumPM10 concentration, source control accounted for 16%, suggesting that meteorology accounted for more of the variation in PM concentration than source control measures. Based on our measurements during the 2008 Olympic time period, the PM10 concentrations in Beijing were 2.9, 3.5, and 1.9 times higher than PM10 concentrations during the Olympic time periods in Atlanta, Sydney and Athens. In addition, the PM10 and PM2.5 concentrations during the Olympic time period exceeded the WHO guideline 81% and 100% of the time, respectively. Finally, compared to October, November, and December 2007, the PM10 concentrations were reduced by 9% to 27% during the same months in 2008, suggesting that the source control efforts (and possibly a down turn in the economy) have resulted in lower PM10 concentrations in Beijing.
Air Quality Measurements from Satellites during the 2008 Beijing Olympics and Paralympics
In preparation for the Olympic and Paralympic games in August and September 2008 in Beijing, China, the Chinese government imposed strict controls on industrial emissions and motor vehicle traffic in and around the city and vicinity before and during the events to improve the air quality for the competitors and visitors. To test the efficacy of these measures, we used satellite data from NASA's Aura/Ozone Monitoring Instrument (OMI) and Terra/Measurements Of Pollution In The Troposphere (MOPITT) over Beijing and surrounding areas during the Olympic and Paralympic period. The satellite instruments recorded significant reductions in nitrogen dioxide of up to 50%, up to 10% in tropospheric column ozone, 20-40% in boundary layer sulfur dioxide, and 10-20% reductions in carbon monoxide concentrations below 700 hPa.