Trace gas measurements and air mass classification from a ground station in Taiwan during the PEM‐West A experiment (1991)

Buhr, M. P.; Hsu, Kuan-Lun; Liu, C. M.; Liu, R.; Wei, Liu; Liu, Y.-C.; Kuo, Yi‐Ming

doi:10.1029/95jd00411

Cited by 25 publications

(11 citation statements)

References 15 publications

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“…This may reflect the fact the air mass from the central northern Pacific sometimes has to pass over the large emission source region of southern Taiwan Island and the eastern coast of south China as revealed by individual trajectory. The median ozone concentrations associated with maritime air masses from the central Pacific and the South China Sea measured at Cape D'Aguilar in summer (21 and 13 ppbv respectively) are comparable in magnitude to those observed at Oki, Okinawa of Japan (11–15 and 22 ppbv respectively) and Kenting of Taiwan (9 and 18 ppbv respectively) [ Akimoto et al , 1996; Buhr et al , 1996].…”

Section: Resultsmentioning

confidence: 82%

“…Chan et al [1998aChan et al [ , 1998b proposed that the changes of prevalent maritime and continental air mass flow are important factors governing the variation of surface ozone in Hong Kong. Buhr et al [1996] and Wang et al…”

Section: Introductionmentioning

confidence: 95%

“… Chan et al [1998a, 1998b] proposed that the changes of prevalent maritime and continental air mass flow are important factors governing the variation of surface ozone in Hong Kong. Buhr et al [1996] and Wang et al [1997] revealed through trace gas measurements in southern Taiwan and Hong Kong respectively that high levels of trace gases are associated with continental outflows reaching south China and Hong Kong. Chan and Chan [2000] found that the background outflow of Asian pollutants can be significantly modified on their way to the Pacific Ocean when passing through the industrialized and urbanized south China region.…”

Section: Introductionmentioning

confidence: 99%

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Effects of Asian air pollution transport and photochemistry on carbon monoxide variability and ozone production in subtropical coastal south China

Chan

Lam

et al. 2002

J.‐Geophys.‐Res.

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[1] Surface ozone and carbon monoxide (CO) measured from a relatively remote coastal station in Hong Kong are analyzed to study the effects of pollutant transport and associated ozone production on CO and ozone variations in the subtropical south China region. CO and ozone concentrations show a common minimum in summer and in the maritime air masses from the South China Sea and Pacific Ocean. They have higher values in other seasons and in the continental air masses that have passed over mainland Asia and the East Asian coast. CO shows the maximum monthly median of 457-552 ppbv in winter while ozone shows a maximum of 40-50 ppbv in autumn and a distinct peak of 41-43 ppbv in spring. The CO concentrations especially in the continental air masses (median of 277 to 428 ppbv) are very high when compared with measurements in most parts of the world. This suggests that the south China region is under the strong influence of pollutant transport from the Asian continent and East Asian coast. Ozone and CO show strong positive correlations in the polluted maritime air masses and from late spring to early autumn (May-September) with the linear regression slopes of the ozone-CO plot from 0.08 to 0.22 (with respective standard errors from 0.01 to 0.03). The strong correlations and slopes plus the high CO levels indicate that there is substantial ozone production from pollution in the polluted maritime air masses and in the late spring to early autumn period.

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Section: Resultsmentioning

confidence: 82%

Section: Introductionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

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Effects of Asian air pollution transport and photochemistry on carbon monoxide variability and ozone production in subtropical coastal south China

Chan

Lam

et al. 2002

J.‐Geophys.‐Res.

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“…The seasonal ΔO 3 /ΔNO y averages indicate an approximately 80‐fold, 100‐fold, and 60‐fold enrichment of O 3 relative to NO y (ppbv ppbv −1 ) during spring and fall, summer, and winter, respectively. The ΔO 3 /ΔNO y of 100 ppbv ppbv −1 is an order of magnitude higher than that observed in several rural sites in North America during the summer seasons (8.5–10 ppbv ppbv −1 [ Trainer et al , 1993; Olszyna et al , 1994]), is on the upper limit of what was encountered in the FT over North America (∼38–100 ppbv ppbv −1 [ Ridley et al , 1994]) and is moderately larger than those reported over the western North Atlantic region (∼10–50 ppbv ppbv −1 [ Buhr et al , 1996]). The summer ΔO 3 /ΔNO y observed at the Pico Mountain station is thus consistent with formation of O 3 over the continent and adjacent region, followed by a high NO y loss (via HNO 3 wet/dry deposition) and moderate O 3 destruction during transit to the measurement site.…”

Section: Impacts Of North American Anthropogenic Emissionsmentioning

confidence: 79%

Large‐scale impacts of anthropogenic pollution and boreal wildfires on the nitrogen oxides over the central North Atlantic region

Martin¹,

Honrath²,

Owen³

et al. 2008

J. Geophys. Res.

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[1] Transport of North American anthropogenic and boreal wildfire emissions is a large source of nitrogen oxides over the North Atlantic region. To characterize the influence of transport of these emissions on nitrogen oxides levels over the central North Atlantic lower free troposphere (FT) emissions to the FT based on observed DNO y /DCO in the anthropogenic plumes indicates that more than 94% of the NO x emitted over the United States is lost within the continent and/or during export out of the United States boundary layer and to the Azores, consistent with previous studies. However, our observations indicate that about 30% of the NO y initially exported out of the United States boundary layer reach the Azores lower FT. NO x was also significantly enhanced in these plumes. Since the lifetime of NO x is shorter than the transport timescale of most events, PAN decomposition and potentially photolysis of HNO 3 provide a supply of NO x over the central North Atlantic lower FT. Observed DO 3 /DNO y ratios and significant NO y levels remaining in the North American plumes suggest a potential for O 3 formation well downwind from North America. Summertime boreal wildfires in North America are responsible for important shifts in the nitrogen oxides distributions toward higher levels, with medians of NO y (117-175 pptv) and NO x (9-30 pptv) greater in boreal wildfire plumes. These findings demonstrate the potential hemispheric scale impact that boreal wildfire and North American anthropogenic events have on background NO x and NO y levels and on the tropospheric O 3 budget.Citation: Val Martin, M., R. E. Honrath, R. C. Owen, and K. Lapina (2008), Large-scale impacts of anthropogenic pollution and boreal wildfires on the nitrogen oxides over the central North Atlantic region,

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“…These long‐term ambient air measurements taken in Taiwan can be used to document both chemical (e.g., chemical climatology) and transport characteristics (e.g., transport corridors) of the Asian continental outflows, including seasonal and interannual variability, long‐term trends, and the effect of climate change on long‐range transport [ CENR , 2001]. For example, Oltmans et al [2004] showed that long‐range transport of pollution from China in the spring affects boundary‐layer ozone concentrations at Taipei (25°N, 121.5°E); Taiwan has been one of the major sites in several Pacific field campaigns such as the Pacific Exploratory Missions [ Buhr et al , 1996; Arimoto et al , 1996; Akimoto et al , 1996; Liu et al , 1997; Arimoto et al , 1997; Board et al , 1999], ACE‐Asia [ Huebert et al , 2003], and TRACE‐P [ Jacob et al , 2003; Wild et al , 2004; Oltmans et al , 2004].…”

Section: Introductionmentioning

confidence: 99%

A 9‐year climatology of airstreams in East Asia and implications for the transport of pollutants and downstream impacts

Wang¹

2005

J. Geophys. Res.

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[1] Ambient measurements of PM 10 levels in Taiwan over East Asia have shown unusual decreases for the 1994-2002 period. To assess these downward trends of PM 10 , we develop methods for calculating climatologies of PM 10 and airstreams, and a new method for quantifying airstreams and their associated impacts on PM 10 and PM 10 -influencing factors. These methods were verified against anomalously low PM 10 levels during the 1998 ENSO, and anomalously high PM 10 levels during spring 2000. Calculations show the following: 20-23% increased occurrence of airstreams from the north direction in spring 2000 coincide with 14-16% increases in ambient PM 10 levels downstream over Taiwan; 60% increased occurrence of airstreams over western Pacific coincide with 10-15% drops in ambient PM 10 levels downstream during the 1998 ENSO. Comparison of airstreams between 1994-1997 and 1999-2002 show a 15-29% reduction over the eastern direction and a 7-17% increase over the western direction. The most significant findings associated with these changes are the reduction in close-to-surface inversions, the increase in rainfall, the increase in continental outflows, and the counteracting effects between these processes. The reduction in close-to-surface inversions dilutes ambient particles from the surface toward the free troposphere, thereby reducing ambient PM 10 levels; increases in rainfall provide efficient wet scavenging mechanisms for removing particles from the ambient air. These two processes counteract and dominate over the increase in airstreams over the northwestern direction, where continental pollutants are exported downstream, and results in the downward trends in PM 10 .

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Trace gas measurements and air mass classification from a ground station in Taiwan during the PEM‐West A experiment (1991)

Cited by 25 publications

References 15 publications

Effects of Asian air pollution transport and photochemistry on carbon monoxide variability and ozone production in subtropical coastal south China

Effects of Asian air pollution transport and photochemistry on carbon monoxide variability and ozone production in subtropical coastal south China

Large‐scale impacts of anthropogenic pollution and boreal wildfires on the nitrogen oxides over the central North Atlantic region

A 9‐year climatology of airstreams in East Asia and implications for the transport of pollutants and downstream impacts

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