HOME / 出版文献 /

Nielsen, Chris P.

2013
Chris P Nielsen and Mun S Ho. 2013. “Op-ed: Clearing the air in China.” New York Times (Sunday Review), October 27 , Pp. SR4. Publisher's Version
Xi Lu, Michael B. McElroy, Chris P Nielsen, Xinyu Chen, and Junling Huang. 2013. “Optimal integration of offshore wind power for a steadier, environmentally friendlier, supply of electricity in China.” Energy Policy, 62, Pp. 131–138. Publisher's VersionAbstract

Demand for electricity in China is concentrated to a significant extent in its coastal provinces. Opportunities for production of electricity by on-shore wind facilities are greatest, however, in the north and west of the country. Using high resolution wind data derived from the GEOS-5 assimilation, this study shows that investments in off-shore wind facilities in these spatially separated regions (Bohai-Bay or BHB, Yangtze-River Delta or YRD, Pearl-River Delta or PRD) could make an important contribution to overall regional demand for electricity in coastal China. An optimization analysis indicates that hour-to-hour variability of outputs from a combined system can be minimized by investing 24% of the power capacity in BHB, 30% in YRD and 47% in PRD. The analysis suggests that about 28% of the overall off-shore wind potential could be deployed as base load power replacing coal-fired system with benefits not only in terms of reductions in CO2 emissions but also in terms of improvements in regional air quality. The interconnection of off-shore wind resources contemplated here could be facilitated by China's 12th-five-year plan to strengthen inter-connections between regional electric-power grids.

Final Manuscript in DASH
Yu Lei, Qiang Zhang, Chris P Nielsen, and Kebin He. 2013. “Primary Air Pollutants and CO2 Emissions from Cement Production in China.” In Clearer Skies Over China: Reconciling Air Quality, Climate, and Economic Goals, Pp. 203-224. Cambridge, MA: MIT Press. Publisher's VersionAbstract

A groundbreaking U.S.–Chinese inquiry into the effects of recent air pollution controls and prospective carbon taxes on China's economy and environment.

China's carbon dioxide emissions now outstrip those of other countries and its domestic air quality is severely degraded, especially in urban areas. Its sheer size and its growing, fossil-fuel-powered economy mean that China's economic and environmental policy choices will have an outsized effect on the global environmental future. Over the last decade, China has pursued policies that target both fossil fuel use and atmospheric emissions, but these efforts have been substantially overwhelmed by the country's increasing energy demands. With a billion citizens still living on less than $4,000 per year, China's energy and environmental policies must be reconciled with the goals of maintaining economic growth and raising living standards.

This book, a U.S.–Chinese collaboration of experts from Harvard and Tsinghua University, offers a groundbreaking integrated analysis of China's economy, emissions, air quality, public health, and agriculture. It first offers essential scientific context and accessible summaries of the book's policy findings; it then provides the underlying scientific and economic research. These studies suggest that China's recent sulfur controls achieved enormous environmental health benefits at unexpectedly low costs. They also indicate that judicious implementation of carbon taxes could reduce not only China's carbon emissions but also its air pollution more comprehensively than current single-pollutant policies, all at little cost to economic growth.

Chris P Nielsen, Mun S Ho, Jing Cao, Yu Lei, Yuxuan Wang, and Yu Zhao. 2013. “Summary: Carbon Taxes for 2013-2020.” In Clearer Skies Over China: Reconciling Air Quality, Climate, and Economic Goals, Pp. 103-157. Cambridge, MA: MIT Press. Publisher's VersionAbstract

A groundbreaking U.S.–Chinese inquiry into the effects of recent air pollution controls and prospective carbon taxes on China's economy and environment.

China's carbon dioxide emissions now outstrip those of other countries and its domestic air quality is severely degraded, especially in urban areas. Its sheer size and its growing, fossil-fuel-powered economy mean that China's economic and environmental policy choices will have an outsized effect on the global environmental future. Over the last decade, China has pursued policies that target both fossil fuel use and atmospheric emissions, but these efforts have been substantially overwhelmed by the country's increasing energy demands. With a billion citizens still living on less than $4,000 per year, China's energy and environmental policies must be reconciled with the goals of maintaining economic growth and raising living standards.

This book, a U.S.–Chinese collaboration of experts from Harvard and Tsinghua University, offers a groundbreaking integrated analysis of China's economy, emissions, air quality, public health, and agriculture. It first offers essential scientific context and accessible summaries of the book's policy findings; it then provides the underlying scientific and economic research. These studies suggest that China's recent sulfur controls achieved enormous environmental health benefits at unexpectedly low costs. They also indicate that judicious implementation of carbon taxes could reduce not only China's carbon emissions but also its air pollution more comprehensively than current single-pollutant policies, all at little cost to economic growth.

Chris P Nielsen, Mun S Ho, Yu Zhao, Yuxuan Wang, Yu Lei, and Jing Cao. 2013. “Summary: Sulfur Mandates and Carbon Taxes for 2006-2010.” In Clearer Skies Over China: Reconciling Air Quality, Climate, and Economic Goals, Pp. 59-102. Cambridge, MA: MIT Press. Publisher's VersionAbstract

A groundbreaking U.S.–Chinese inquiry into the effects of recent air pollution controls and prospective carbon taxes on China's economy and environment.

China's carbon dioxide emissions now outstrip those of other countries and its domestic air quality is severely degraded, especially in urban areas. Its sheer size and its growing, fossil-fuel-powered economy mean that China's economic and environmental policy choices will have an outsized effect on the global environmental future. Over the last decade, China has pursued policies that target both fossil fuel use and atmospheric emissions, but these efforts have been substantially overwhelmed by the country's increasing energy demands. With a billion citizens still living on less than $4,000 per year, China's energy and environmental policies must be reconciled with the goals of maintaining economic growth and raising living standards.

This book, a U.S.–Chinese collaboration of experts from Harvard and Tsinghua University, offers a groundbreaking integrated analysis of China's economy, emissions, air quality, public health, and agriculture. It first offers essential scientific context and accessible summaries of the book's policy findings; it then provides the underlying scientific and economic research. These studies suggest that China's recent sulfur controls achieved enormous environmental health benefits at unexpectedly low costs. They also indicate that judicious implementation of carbon taxes could reduce not only China's carbon emissions but also its air pollution more comprehensively than current single-pollutant policies, all at little cost to economic growth.

2012
Xi Lu, Michael B. McElroy, Gang Wu, and Chris P Nielsen. 2012. “Accelerated reduction of SO2 emissions from the US power sector triggered by changing prices of natural gas.” Environmental Science and Technology, 46, 14, Pp. 7882-7889. Publisher's VersionAbstract
Emissions of sulfur dioxide (SO2) from the U.S. power sector decreased by 24% in 2009 relative to 2008. The Logarithmic Mean Divisia Index (LMDI) approach was applied to isolate the factors responsible for this decrease. It is concluded that 15% of the decrease can be attributed to the drop in demand for electricity triggered by the economic recession, and 28% can be attributed to switching of fuel from coal to gas responding to the decrease in prices for the latter. The largest factor in the decrease, close to 57%, resulted from an overall decline in emissions per unit of power generated from coal. This is attributed in part to selective idling of older, less efficient coal plants that generally do not incorporate technology for sulfur removal, and in part to continued investments by the power sector in removal equipment in response to the requirements limiting emissions imposed by the U.S. Environmental Protection Agency (U.S. EPA). The paper argues further that imposition of a modest tax on emissions of carbon would have ancillary benefits in terms of emissions of SO2.

Final Manuscript in DASH
This paper is from a series investigating and comparing the prospects for low- and non-carbon power generation in China and the U.S.

Yu Zhao, Chris P Nielsen, and Michael B. McElroy. 2012. “China's CO2 emissions estimated from the bottom up: Recent trends, spatial distributions, and quantification of uncertainties.” Atmospheric Environment, 59, Pp. 214-223. Publisher's VersionAbstract
China's emissions of anthropogenic CO2 are estimated using a bottom-up emission inventory framework based on a detailed categorization of economic sectors and provincial economic and energy data. It includes a newly compiled database of CO2 emission factors employing the latest field study results from China. Total annual emissions are estimated to have risen from 7126 to 9370 Mt CO2 from 2005 to 2009. Recent policies to conserve energy and reduce emissions have been effective in limiting CO2 emissions from power and iron & steel plants, but have had little effect on those from cement production. The uncertainties of China's CO2 emissions are quantified for the first time using Monte-Carlo simulation, producing a 95% confidence interval (CI) of −9% to +11% for total emissions in 2005. The largest contributors to sector-level emission uncertainty are emission factors for most industrial sources and activity levels for power plants, transportation, and residential & commercial sources. Application of province-level energy consumption and China-specific emission factors in some sectors results in higher annual emission estimates for 2005-2008 as compared with other studies, although most of those are within the 95% CIs of this study.

Final Manuscript in DASH
Click here to see coverage in United Press International (http://www.upi.com/Science_News/2012/07/06/Estimate-of-China-emission-sa...) and ScienceDaily (http://www.sciencedaily.com/releases/2012/07/120706105419.htm).

Yu Zhao, Chris P Nielsen, Michael B. McElroy, Lin Zhang, and Jie Zhang. 2012. “CO emissions in China: Uncertainties and implications of improved energy efficiency and emission control.” Atmospheric Environment, 49, Pp. 103-113. Publisher's VersionAbstract
A bottom-up methodology and an improved database of emission factors combining the latest domestic field measurements are developed to estimate the emissions of anthropogenic CO from China at national and provincial levels. The CO emission factors for major economic sectors declined to varying degrees from 2005 to 2009, attributed to improved energy efficiency and/or emission control regulations. Total national CO emissions are estimated at 173 Tg for 2005 and have been relatively stable for subsequent years, despite fast growth of energy consumption and industrial production. While industry and transportation sources dominated CO emissions in developed eastern and north-central China, residential combustion played a much greater role in the less developed western provinces. The uncertainties of national Chinese CO emissions are quantified using Monte Carlo simulation at −20% to +45% (95% confidence interval). Due to poor understanding of emission factors and activity levels for combustion of solid fuels, the largest uncertainties are found for emissions from the residential sector. The trends of bottom-up emissions compare reasonably to satellite observation of CO columns and to ground observations of CO2–CO correlation slopes. The increase in the ratio for emissions of CO2 relative to CO suggests that China has successfully improved combustion efficiencies across its economy in recent years, consistent with national policies to improve energy efficiency and to control criteria air pollutants.
Final Manuscript in DASH
Gang Wu, Yi-Ming Wei, Chris P Nielsen, Xi Lu, and Michael B. McElroy. 2012. “A dynamic programming model of China's strategic petroleum reserve: General strategy and the effect of emergencies.” Energy Economics, 34, 4, Pp. 1234-1243. Publisher's VersionAbstract
To protect the security of energy supply, China is building national strategic petroleum reserve (SPR). We present a dynamic programming model to determine the optimal stockpiling and drawdown strategies for China's SPR under various scenarios, focusing on minimizing the total cost of reserves. In contrast to previous research, the oil price given in our model is exogenous on a monthly instead of annual basis, with a view to more realistic simulation of optimal strategies each year. Our model results show that in the case where stockpiling affects oil prices, a given SPR size will be achieved earlier than when stockpiling does not affect oil prices. In different emergency conditions, the optimal stockpiling and drawdown strategies of China's SPR are very different. When an emergency occurs, the shock of stockpiling on the oil price per barrel could range $0.49–$6.35, while the impact of drawdown on the oil price per barrel could range −$6.22 to −$0.48.
2011
Xi Lu, Jeremy Tchou, Michael B. McElroy, and Chris P Nielsen. 2011. “The impact of production tax credits on the profitable production of electricity from wind in the U.S.” Energy Policy, 39, 7, Pp. 4207-4214. Publisher's VersionAbstract
A spatial financial model using wind data derived from assimilated meteorological condition was developed to investigate the profitability and competitiveness of onshore wind power in the contiguous U.S. It considers not only the resulting estimated capacity factors for hypothetical wind farms but also the geographically differentiated costs of local grid connection. The levelized cost of wind-generated electricity for the contiguous U.S. is evaluated assuming subsidy levels from the Production Tax Credit (PTC) varying from 0 to 4 ¢/kWh under three cost scenarios: a reference case, a high cost case, and a low cost case. The analysis indicates that in the reference scenario, current PTC subsidies of 2.1 ¢/kWh are at a critical level in determining the competitiveness of wind-generated electricity compared to conventional power generation in local power market. Results from this study suggest that the potential for profitable wind power with the current PTC subsidy amounts to more than seven times existing demand for electricity in the entire U.S. Understanding the challenges involved in scaling up wind energy requires further study of the external costs associated with improvement of the backbone transmission network and integration into the power grid of the variable electricity generated from wind.

This paper is from a series investigating and comparing the prospects for low- and non-carbon power generation in China and the U.S.

Yu Lei, Qiang Zhang, Chris P Nielsen, and Kebin He. 2011. “An inventory of primary air pollutants and CO2 emissions from cement production in China, 1990-2020.” Atmospheric Environment, 45, 1, Pp. 147-154. Publisher's VersionAbstract
Direct emissions of air pollutants from the cement industry in China were estimated by developing a technology-based methodology using information on the proportion of cement produced from different types of kilns and the emission standards for the Chinese cement industry. Historical emissions of sulfur dioxide (SO2), nitrogen oxides (NOX), carbon monoxide (CO), particulate matter (PM) and carbon dioxide (CO2) were estimated for the years 1990–2008, and future emissions were projected up to 2020 based on current energy-related and emission control policies. Compared with the historical high (4.36 Tg of PM2.5, 7.16 Tg of PM10 and 10.44 Tg of TSP in 1997), PM emissions are predicted to drop substantially by 2020, despite the expected tripling of cement production. Certain other air pollutant emissions, such as CO and SO2, are also predicted to decrease with the progressive closure of shaft kilns. NOX emissions, however, could increase because of the promotion of precalciner kilns and the rapid increase of cement production. CO2 emissions from the cement industry account for approximately one eighth of China’s national CO2 emissions. Our analysis indicates that it is possible to reduce CO2 emissions from this industry by approximately 12.8% if advanced energy-related technologies are implemented. These technologies will bring co-benefits in reducing other air pollutants as well.
Final Manuscript in DASH
Yu Zhao, Michael B. McElroy, Jia Xing, Lei Duan, Chris P Nielsen, Yu Lei, and Jiming Hao. 2011. “Multiple effects and uncertainties of emission control policies in China: Public health, soil acidification, and global temperature.” Science of the Total Environment , 409, 24, Pp. 5177-5187. Publisher's VersionAbstract
Policies to control emissions of criteria pollutants in China may have conflicting impacts on public health, soil acidification, and climate. Two scenarios for 2020, a base case without anticipated control measures and a more realistic case including such controls, are evaluated to quantify the effects of the policies on emissions and resulting environmental outcomes. Large benefits to public health can be expected from the controls, attributed mainly to reduced emissions of primary PM and gaseous PM precursors, and thus lower ambient concentrations of PM2.5. Approximately 4% of all-cause mortality in the country can be avoided (95% confidence interval: 1–7%), particularly in eastern and north-central China, regions with large population densities and high levels of PM2.5. Surface ozone levels, however, are estimated to increase in parts of those regions, despite NOX reductions. This implies VOC-limited conditions. Even with significant reduction of SO2 and NOX emissions, the controls will not significantly mitigate risks of soil acidification, judged by the exceedance levels of critical load (CL). This is due to the decrease in primary PM emissions, with the consequent reduction in deposition of alkaline base cations. Compared to 2005, even larger CL exceedances are found for both scenarios in 2020, implying that PM control may negate any recovery from soil acidification due to SO2 reductions. Noting large uncertainties, current polices to control emissions of criteria pollutants in China will not reduce climate warming, since controlling SO2 emissions also reduces reflective secondary aerosols. Black carbon emission is an important source of uncertainty concerning the effects of Chinese control policies on global temperature change. Given these conflicts, greater consideration should be paid to reconciling varied environmental objectives, and emission control strategies should target not only criteria pollutants but also species such as VOCs and CO2.
Final Manuscript in DASH
Yu Zhao, Chris P Nielsen, Yu Lei, Michael B. McElroy, and Jiming Hao. 2011. “Quantifying the uncertainties of a bottom-up emission inventory of anthropogenic atmospheric pollutants in China.” Atmospheric Chemistry and Physics, 11, Pp. 2295-2308. Publisher's VersionAbstract
The uncertainties of a national, bottom-up inventory
of Chinese emissions of anthropogenic SO2, NOx, and
particulate matter (PM) of different size classes and carbonaceous
species are comprehensively quantified, for the first
time, using Monte Carlo simulation. The inventory is structured
by seven dominant sectors: coal-fired electric power,
cement, iron and steel, other industry (boiler combustion),
other industry (non-combustion processes), transportation,
and residential. For each parameter related to emission factors
or activity-level calculations, the uncertainties, represented
as probability distributions, are either statistically fitted
using results of domestic field tests or, when these are
lacking, estimated based on foreign or other domestic data.
The uncertainties (i.e., 95% confidence intervals around the
central estimates) of Chinese emissions of SO2, NOx, total
PM, PM10, PM2.5, black carbon (BC), and organic carbon
(OC) in 2005 are estimated to be −14%13%, −13%37%,
−11%38%, −14%45%, −17%54%, −25%136%,
and −40%121%, respectively. Variations at activity levels
(e.g., energy consumption or industrial production) are
not the main source of emission uncertainties. Due to narrow
classification of source types, large sample sizes, and
relatively high data quality, the coal-fired power sector is estimated
to have the smallest emission uncertainties for all
species except BC and OC. Due to poorer source classifications
and a wider range of estimated emission factors,
considerable uncertainties of NOx and PM emissions from
cement production and boiler combustion in other industries
are found. The probability distributions of emission
factors for biomass burning, the largest source of BC and
OC, are fitted based on very limited domestic field measurements,
and special caution should thus be taken interpreting
these emission uncertainties. Although Monte Carlo simulation
yields narrowed estimates of uncertainties compared
to previous bottom-up emission studies, the results are not
always consistent with those derived from satellite observations.
The results thus represent an incremental research
advance; while the analysis provides current estimates of
uncertainty to researchers investigating Chinese and global
atmospheric transport and chemistry, it also identifies specific
needs in data collection and analysis to improve on
them. Strengthened quantification of emissions of the included
species and other, closely associated ones – notably
CO2, generated largely by the same processes and thus subject
to many of the same parameter uncertainties – is essential
not only for science but for the design of policies to redress
critical atmospheric environmental hazards at local, regional,
and global scales.
Final Manuscript in DASH
Yu Zhao, Lei Duan, Yu Lei, Jia Xing, Chris P Nielsen, and Jiming Hao. 2011. “Will PM control undermine China's efforts to reduce soil acidification?” Environmental Pollution, 159, 10, Pp. 2726-2732. Publisher's VersionAbstract
China’s strategies to control acidifying pollutants and particulate matter (PM) may be in conflict for soil acidification abatement. Acidifying pollutant emissions are estimated for 2005 and 2020 with anticipated control policies. PM emissions including base cations (BCs) are evaluated with two scenarios, a base case applying existing policy to 2020, and a control case including anticipated tightened measures. Depositions of sulfur (S), nitrogen (N) and BCs are simulated and their acidification risks are evaluated with critical load (CL). In 2005, the area exceeding CL covered 15.6% of mainland China, with total exceedance of 2.2 Mt S. These values decrease in the base scenario 2020, implying partial recovery from acidification. Under more realistic PM control, the respective estimates are 17.9% and 2.4 Mt S, indicating increased acidification risks due to abatement of acid-neutralizing BCs. China’s anthropogenic PM abatement will have potentially stronger chemical implications for acidification than developed countries.
2010
Yuxuan Wang, J. William Munger, Shicheng Xu, Michael B. McElroy, Jiming Hao, Chris P Nielsen, and Hong Ma. 2010. “CO2 and its correlation with CO at a rural site near Beijing: Implications for combustion efficiency in China.” Atmospheric Chemistry and Physics, 10, Pp. 8881-8897. Publisher's VersionAbstract
Although China has surpassed the United States as the world’s largest carbon dioxide emitter, in situ measurements of atmospheric CO2 have been sparse in China.
This paper analyzes hourly CO2 and its correlation with CO at Miyun, a rural site near Beijing, over a period of 51 months (Dec 2004 through Feb 2009). The CO2-CO correlation analysis evaluated separately for each hour of the day provides useful information with statistical significance even in the growing season. We found that the intercept, representing the initial condition imposed by global distribution of CO2 with influence of photosynthesis and respiration, exhibits diurnal cycles differing by season. The background CO2 (CO2,b) derived from Miyun observations is comparable to CO2 observed at a Mongolian background station to the northwest.  Annual growth of overall mean CO2 at Miyun is estimated at 2.7 ppm yr−1 while that of CO2,b is only 1.7 ppm yr−1 similar to the mean growth rate at northern mid-latitude background stations. This suggests a relatively faster increase in the regional CO2 sources in China than the global average, consistent with bottom-up studies of CO2 emissions. For air masses with trajectories through the northern China boundary layer, mean winter CO2/CO correlation slopes (dCO2/dCO) increased by 2.8±0.9 ppmv/ppmv or 11% from 2005–2006 to 2007–2008, with CO2 increasing by 1.8 ppmv. The increase in dCO2/dCO indicates improvement in overall combustion efficiency over northern China after winter 2007, attributed to pollution reduction measures associated with the 2008 Beijing Olympics. The observed CO2/CO ratio at Miyun is
25% higher than the bottom-up CO2/CO emission ratio, suggesting a contribution of respired CO2 from urban residents as well as agricultural soils and livestock in the observations and uncertainty in the emission estimates. 
Final Manuscript in DASH
Yu Zhao, Shuxiao Wang, Chris P Nielsen, Xinghua Li, and Jiming Hao. 2010. “Establishment of a database of emission factors for atmospheric pollutant emissions from Chinese coal-fired power plants.” Atmospheric Environment, 44, 12, Pp. 1515-1523. Publisher's VersionAbstract
Field measurements and data investigations were conducted for developing an emission factor database for inventories of atmospheric pollutants from Chinese coal-fired power plants. Gaseous pollutants and particulate matter (PM) of different size fractions were measured using a gas analyzer and an electric low-pressure impactor (ELPI), respectively, for ten units in eight coal-fired power plants across the country. Combining results of field tests and literature surveys, emission factors with 95% confidence intervals (CIs) were calculated by boiler type, fuel quality, and emission control devices using bootstrap and Monte Carlo simulations. The emission factor of uncontrolled SO2 from pulverized combustion (PC) boilers burning bituminous or anthracite coal was estimated to be 18.0S kg t−1 (i.e., 18.0 × the percentage sulfur content of coal, S) with a 95% CI of 17.2S–18.5S. NOX emission factors for pulverized-coal boilers ranged from 4.0 to 11.2 kg t−1, with uncertainties of 14–45% for different unit types. The emission factors of uncontrolled PM2.5, PM10, and total PM emitted by PC boilers were estimated to be 0.4A (where A is the percentage ash content of coal), 1.5A and 6.9A kg t−1, respectively, with 95% CIs of 0.3A–0.5A, 1.1A–1.9A and 5.8A–7.9A. The analogous PM values for emissions with electrostatic precipitator (ESP) controls were 0.032A (95% CI: 0.021A–0.046A), 0.065A (0.039A–0.092A) and 0.094A (0.0656A–0.132A) kg t−1, and 0.0147A (0.0092–0.0225A), 0.0210A (0.0129A–0.0317A), and 0.0231A (0.0142A–0.0348A) for those with both ESP and wet flue-gas desulfurization (wet-FGD). SO2 and NOX emission factors for Chinese power plants were smaller than those of U.S. EPA AP-42 database, due mainly to lower heating values of coals in China. PM emission factors for units with ESP, however, were generally larger than AP-42 values, because of poorer removal efficiencies of Chinese dust collectors. For units with advanced emission control technologies, more field measurements are needed to reduce emission factor uncertainties.
Jintai Lin, Chris P Nielsen, Yu Zhao, Yu Lei, Yang Liu, and Michael B. McElroy. 2010. “Recent changes in particulate air pollution over China observed from space and ground: Effectiveness of emission control.” Environmental Science and Technology, 44, 20, Pp. 7771-7776. Publisher's VersionAbstract
The Chinese government has moved aggressively since 2005 to reduce emissions of a number of pollutants including primary particulate matter (PM) and sulfur dioxide (SO2), efforts inadvertently aided since late 2008 by economic recession. Satellite observations of aerosol optical depth (AOD) and column nitrogen dioxide (NO2) provide independent indicators of emission trends, clearly reflecting the sharp onset of the recession in the fall of 2008 and rebound of the economy in the latter half of 2009. Comparison of AOD with ground-based observations of PM over a longer period indicate that emission-control policies have not been successful in reducing concentrations of aerosol pollutants at smaller size range over industrialized regions of China. The lack of success is attributed to the increasing importance of anthropogenic secondary aerosols formed from precursor species including nitrogen oxides (NOx), non-methane volatile organic compounds (NMVOC), and ammonia (NH3).
Final Manuscript in DASH
Yuxuan Wang, Michael B. McElroy, J. William Munger, Jiming Hao, Hong Ma, and Chris P Nielsen. 2010. “Year-round measurements of O3 and CO at a rural site near Beijing: Variations in their correlations.” Tellus B: Chemical and Physical Meteorology, 62, 4, Pp. 228-241. Publisher's VersionAbstract
Read the full text
 
    ePDFPDF
    Tools
     

    ABSTRACT

    We examine seasonal variations of carbon monoxide (CO), ozone (O3), and their relationships observed over the course of 3 yr (2005–2007) at Miyun, a rural site 100 km north of Beijing. Monthly mean afternoon mixing ratios of CO have broad maxima in winter and a secondary peak in June. Monthly mean afternoon O3 shows a clear seasonal pattern with a major peak in June (85 ppb), a secondary peak in September (65 ppb) and minimum in winter (50–55 ppb). The seasonal cycles of O3 and CO are associated with seasonal changes in dominant synoptic pattern. Substantial interannual variability is found for CO which is attributed to the interannual variability of meteorology and emissions from biomass burning. The seasonality and magnitude of background CO and O3 derived at Miyun are consistent with observations at upwind remote continental sites. The O3–CO correlation slope is about 0.07 ppb ppb−1 on average in summer, significantly lower than the typical slope of 0.3 ppb ppb−1 reported for developed countries. The O3–CO correlation slope shows large gradients for different types of air masses (0.133 ± 0.017 ppb ppb−1 in aged urban pollution plumes and 0.047 ± 0.008 ppb ppb−1 in biomass burning plumes), suggesting that the conventional method of direct scaling the mean O3–CO slope by CO emissions to deduce O3 production rate is subject to large uncertainties if applied for China.

    Final Manuscript in DASH
    2009
    Yuxuan Wang, Jiming Hao, Michael B. McElroy, J. William Munger, Hong Ma, Dan Chen, and Chris P Nielsen. 2009. “Ozone air quality during the 2008 Beijing Olympics: Effectiveness of emission restrictions.” Atmospheric Chemistry and Physics, 9, 14, Pp. 5237-5251. Publisher's VersionAbstract
    A series of aggressive measures was launched by
    the Chinese government to reduce pollutant emissions from
    Beijing and surrounding areas during the Olympic Games.
    Observations at Miyun, a rural site 100 km downwind of the
    Beijing urban center, show significant decreases in concentrations
    of O3, CO, NOy, and SO2 during August 2008, relative
    to August 2006–2007. The mean daytime mixing ratio
    of O3 was lower by about 15 ppbv, reduced to 50 ppbv, in
    August 2008. The relative reductions in daytime SO2, CO,
    and NOy were 61%, 25%, and 21%, respectively. Changes in
    SO2 and in species correlations from 2007 to 2008 indicate
    that emissions of SO2, CO, and NOx were reduced at least
    by 60%, 32%, and 36%, respectively, during the Olympics.
    Analysis of meteorological conditions and interpretation of
    observations using a chemical transport model suggest that
    although the day-to-day variability in ozone is driven mostly
    by meteorology, the reduction in emissions of ozone precursors
    associated with the Olympic Games had a significant
    contribution to the observed decrease in O3 during August
    2008, accounting for 80% of the O3 reduction for the
    month as a whole and 45% during the Olympics Period (8–
    24 August). The model predicts that emission restrictions
    such as those implemented during the Olympics can affect
    O3 far beyond the Beijing urban area, resulting in reductions
    in boundary layer O3 of 2–10 ppbv over a large region of the
    North China Plain and Northeastern China.
    Final Manuscript in DASH
    Potential for wind generated electricity in China
    Michael B. McElroy, Xi Lu, Chris P Nielsen, and Yuxuan Wang. 2009. “Potential for wind generated electricity in China.” Science, 325, 5946, Pp. 1378-1380. Publisher's VersionAbstract
    Wind offers an important alternative to coal as a source of energy for generation of electricity in China with the potential for substantial savings in carbon dioxide emissions. Wind fields derived from assimilated meteorological data are used to assess the potential for wind-generated electricity in China subject to the existing government-approved bidding process for new wind farms. Assuming a guaranteed price of 0.516 RMB (7.6 U.S. cents) per kilowatt-hour for delivery of electricity to the grid over an agreed initial average period of 10 years, it is concluded that wind could accommodate all of the demand for electricity projected for 2030, about twice current consumption. Electricity available at a concession price as low as 0.4 RMB per kilowatt-hour would be sufficient to displace 23% of electricity generated from coal.

    Final Manuscript in DASH
    This paper was the cover article of this issue of Science; click here (http://www.sciencemag.org/content/325/5946.cover-expansion) to see the cover image of wind turbines near the Great Wall of China.

    Pages