Evaluation of in situ measurements of atmospheric carbon monoxide at Mount Waliguan, China

Abstract. Quasicontinuous measurements of carbon monoxide (CO) recorded over three years at Mount Waliguan (WLG), a global baseline station in remote western China, were examined using back trajectory analysis. The data include a revision to correct the working reference scale to the WMO2000 scale and corrections for drift in the reference gases. Between July 2004 and June 2007, CO exhibited large fluctuations and the 5 %, 50 % and 95 %-percentiles of relevant CO mixing ratios were 102 ppb, 126 ppb and 194 ppb. Approximately 50 % of all observed data were selected as CO background data using a mathematical procedure of robust local regression, with the remainder affected by regional-scale pollution. The monthly mean background CO mixing ratios showed a minimum in summer and a maximum in late winter, although all seasons were affected by short-term enhancements that exceeded background levels. The CO data were compared to values observed at the high alpine research station at Jungfraujoch, Switzerland. Smaller seasonal amplitudes were observed at WLG compared to the Jungfraujoch due to lower winter and spring CO levels, however, episodic enhancements of polluted air were greater at WLG. The air parcels arriving at WLG came predominately from the west, except in summer when advection from the east and southeast prevailed. Transport from the east or southeast typically brought polluted air to the site, having passed over populated urban areas upwind. A large number of elevated CO mixing ratios could also be associated with advection from the northwest of WLG via the central Xinjiang Uygur Autonomous Region (XUAR) and the Ge'ermu urban area where growing industrial activities as well as crops residue burning provide sources of CO. Air masses passing over northwestern Gansu were associated with relatively high CO values suggesting an anthropogenic influence, which was likely due to anthropogenic emissions from northwestern China (based on back-trajectory and potential source contribution analysis and on the INTEX-B: intercontinental Chemical Transport Experiment-Phase B). Background conditions were observed most frequently in air parcels from remote Tibet west of WLG. The probability that air parcels pass over regions of clean or polluted regions was further identified using potential source contribution function (PSCF) analysis.

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Evaluation of in situ measurements of atmospheric carbon monoxide at Mount Waliguan, China

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-11-1939-2011 ◽

2011 ◽

Vol 11 (1) ◽

pp. 1939-1969 ◽

Cited By ~ 1

Author(s):

F. Zhang ◽

L. X. Zhou ◽

P. C. Novelli ◽

D. E. J. Worthy ◽

C. Zellweger ◽

...

Keyword(s):

Carbon Monoxide ◽

Urban Areas ◽

Regional Scale ◽

Western China ◽

Back Trajectory ◽

Late Winter ◽

Research Station ◽

Local Regression ◽

Mixing Ratios ◽

Back Trajectory Analysis

Abstract. High frequency measurements of carbon monoxide (CO) recorded over three years at Mount Waliguan (WLG), a global background station in remote western China, were examined using back trajectory analysis. Corrections for the drift in reference gases were also included in the data revision. Between July 2004 and June 2007, a time series of CO exhibited large fluctuations and the 5%, 50% and 95%-percentiles of relevant CO mixing ratios were 102 ppb, 126 ppb and 194 ppb. Approximately 50% of all observed data have been selected as CO background data using a mathematical procedure of robust local regression with the remainder affected by regional-scale pollution. The monthly mean background CO mixing ratios showed a minimum in summer and a maximum in late winter, although all seasons were effected by short-term enhancements that exceeded background levels two or more times. The CO data were compared to the values observed at the high alpine research station Jungfraujoch, Switzerland. Smaller seasonal amplitudes were observed at WLG compared to the Jungfraujoch due to lower winter and spring CO levels, however, episodic enhancements of polluted air were much greater at the site in China. The air parcels arriving at WLG came predominately from the West, except in summer when advection from the East and Southeast prevailed. Transport from the East typically brought polluted air to the site, having passed over populated urban areas upwind. A large number of elevated CO mixing ratios could also be associated with advection from the Northwest of WLG via the central Xinjiang Uygur Autonomous Region (XUAR) and the Ge'ermu urban area where growing industrial activities as well as crops residue burning provide large sources of CO. These background conditions were observed most frequently when air masses originated from remote Tibet west of WLG. The probability that air parcels pass over regions of clean or polluted regions was further identified using potential source contribution function (PSCF) analysis.

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Correlation of black carbon aerosol and carbon monoxide concentrations measured in the high-altitude environment of Mt. Huangshan, Eastern China

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-11-4447-2011 ◽

2011 ◽

Vol 11 (2) ◽

pp. 4447-4485 ◽

Cited By ~ 2

Author(s):

X. L. Pan ◽

Y. Kanaya ◽

Z. F. Wang ◽

Y. Liu ◽

P. Pochanart ◽

...

Keyword(s):

Carbon Monoxide ◽

High Altitude ◽

Black Carbon ◽

Urban Areas ◽

Southern China ◽

Eastern China ◽

Back Trajectory ◽

Strong Positive Correlation ◽

Air Mass ◽

Co Concentration

Abstract. Understanding the relationship between black carbon (BC) and carbon monoxide (CO) will help improve BC emission inventories and the evaluation of global/regional climate forcing effects. In the present work, the BC (PM1) and CO mixing ratio was continuously measured at a~high-altitude background station on the summit of Mt Huangshan between 2006 and 2009. Annual mean BC concentration was 654.6 ± 633.4 ng m−3 with maxima in spring and autumn, when biomass was burned over a large area in Eastern China. The yearly averaged CO concentration was 446.4 ± 167.6 ppbv, and the increase in the CO concentration was greatest in the cold season, implying that the large-scale domestic coal/biofuel combustion for heating has an effect. The BC–CO relationship was found to have different seasonal features but strong positive correlation (R > 0.8). Back trajectory cluster analysis showed that the ΔBC/ΔCO ratio of plumes from the Yangtze River Delta region was 6.58 ± 0.96 ng m−3 ppbv−1, which is consistent with result from INTEX-B emission inventory. The ΔBC/ΔCO ratios for air masses from Northern, Central Eastern and Southern China were 5.2 ± 0.63, 5.65 ± 0.58 and 5.21 ± 0.93 ng m−3 ppbv−1, respectively. Over the whole observation period, the ΔBC/ΔCO ratio had unimodal diurnal variations and had a maximum during the day (09:00–17:00 LST) and minimum at night (21:00–04:00 LST) in spring, summer, autumn and winter, indicating the effects of the intrusion of clean air mass from the high troposphere. The case study combined with measurements of urban PM10 concentrations and satellite observations demonstrated that the ΔBC/ΔCO ratio for a plume of burning biomass was 12.4 ng m−3 ppbv−1 and that for urban plumes in Eastern China was 5.3 ± 0.53 ng m−3 ppbv−1. Transportation and industry were deemed as controlling factors of the BC–CO relationship and major contributions to atmospheric BC and CO loadings in urban areas. The loss of BC during transportation was also investigated on the basis of the ΔBC/ΔCO–RH relationship along air mass pathways, and the results showed that 30–50% BC was lost when air mass traveled under higher RH conditions (>60%) for 2 days.

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Potential Source Contribution Function Analysis of High Latitude Dust Sources over the Arctic: Preliminary Results and Prospects

Atmosphere ◽

10.3390/atmos12030347 ◽

2021 ◽

Vol 12 (3) ◽

pp. 347

Author(s):

Stefano Crocchianti ◽

Beatrice Moroni ◽

Pavla Dagsson Waldhauserová ◽

Silvia Becagli ◽

Mirko Severi ◽

...

Keyword(s):

Transport Processes ◽

The Arctic ◽

Geochemical Data ◽

Back Trajectory ◽

Source Contribution ◽

Source Areas ◽

Geochemical Properties ◽

Potential Source ◽

Dust Sources ◽

Potential Source Contribution Function

The results of a preliminary investigation of the dust sources in the Arctic based on their geochemical properties by potential source contribution function (PSCF) analysis are presented in this paper. For this purpose, we considered one year of aerosol geochemical data from Ny-Ålesund, Svalbard, and a short list of chemical elements (i.e., Al, Fe, Mn, Ti, Cr, V, Ni, Cu, and Zn) variably related to the dust fraction. Based on PSCF analysis: (i) four different dust source areas (i.e., Eurasia, Greenland, Arctic-Alaska, and Iceland) were characterized by distinguishing geochemical ranges and seasonal occurrence; and (ii) a series of typical dust days from the distinct source areas were identified based on the corresponding back trajectory patterns. Icelandic dust samples revealed peculiar but very variable characteristics in relation to their geographical source regions marked by air mass back trajectories. The comparison between pure and mixed Icelandic dust samples (i.e., aerosols containing Icelandic dust along with natural and/or anthropogenic components) revealed the occurrence of different mixing situations. Comparison with Icelandic soils proved the existence of dilution effects related to the emission and the transport processes.

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Interannual variability of ozone and carbon monoxide at the Whistler high elevation site: 2002–2006

Atmospheric Chemistry and Physics ◽

10.5194/acp-11-11431-2011 ◽

2011 ◽

Vol 11 (22) ◽

pp. 11431-11446 ◽

Cited By ~ 35

Author(s):

A. M. Macdonald ◽

K. G. Anlauf ◽

W. R. Leaitch ◽

E. Chan ◽

D. W. Tarasick

Keyword(s):

North American ◽

Forest Fires ◽

High Elevation ◽

Yukon Territory ◽

Back Trajectory ◽

Late Winter ◽

Monthly Means ◽

Air Masses ◽

Mixing Ratios ◽

Western Us

Abstract. In spring 2002, an atmospheric measurement site was established at the peak of Whistler Mountain in British Columbia, Canada to measure trace gases, particle chemistry and physics, and meteorology. This paper uses continuous measurements from March 2002 to December 2006 to investigate the influence of trans-Pacific transport and North American forest fires on both O3 and CO at Whistler. Annual mean mixing ratios of O3 and CO were 41 ppbv (monthly means of 35–48 ppbv) and 145 ppbv (monthly means of 113–177 ppbv) respectively with both species exhibiting an annual cycle of late-winter to early-spring maxima and summer minima. The absence of a broad summer O3 peak differs from previously-reported high altitude sites in the western US. The highest monthly-averaged O3 and CO mixing ratios relative to the 5-yr monthly means were seen in fall 2002 and spring 2003 with increased O3 and CO of 10 % and 25 % respectively. These increases correspond to anomalously-high values reported at other Northern Hemisphere sites and are attributed to fires in the Russian Federation. Air mass back trajectory analysis is used to associate the mean enhancements of O3 and CO with trans-Pacific transported or North American air masses relative to the Pacific background. Mean values of the enhancements for March to June in trans-Pacific air masses were 6 ppbv and 16 ppbv for O3 and CO respectively. In summers 2002–2006, higher CO and O3 mixing ratios were almost always observed in North American air masses and this relative enhancement co-varied for each year with the western US and Canada total wildfire area. The greatest enhancements in O3 and CO were seen in 2004, a record year for forest fires in Alaska and the Yukon Territory with average O3 and CO mixing ratios 13 and 43 ppbv above background values.

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Interannual variability of ozone and carbon monoxide at the Whistler high elevation site: 2002–2006

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-11-17621-2011 ◽

2011 ◽

Vol 11 (6) ◽

pp. 17621-17664 ◽

Cited By ~ 6

Author(s):

A. M. Macdonald ◽

K. G. Anlauf ◽

W. R. Leaitch ◽

E. Chan

Keyword(s):

North American ◽

Forest Fires ◽

High Elevation ◽

Yukon Territory ◽

Back Trajectory ◽

Late Winter ◽

Monthly Means ◽

Air Masses ◽

Mixing Ratios ◽

Western Us

Abstract. In spring 2002, an atmospheric measurement site was established at the peak of Whistler Mountain in British Columbia, Canada to measure trace gases, particle chemistry and physics, and meteorology. This paper uses continuous measurements from March 2002 to December 2006 to investigate the influence of trans-Pacific transport and North American forest fires on both O3 and CO at Whistler. Annual mean mixing ratios of O3 and CO were 41 ppbv (monthly means of 35–48 ppbv) and 145 ppbv (monthly means of 113–177 ppbv) respectively with both species exhibiting an annual cycle of late-winter to early-spring maxima and summer minima. The absence of a broad summer O3 peak differs from previously-reported high altitude sites in the western US. The highest monthly-averaged O3 and CO mixing ratios relative to the 5-year monthly means were seen in fall 2002 and spring 2003 with increased O3 and CO of 10 % and 25 % respectively. These increases correspond to anomalously-high values reported at other Northern Hemisphere sites and are attributed to fires in the Russian Federation. Air mass back trajectory analysis is used to associate the mean enhancements of O3 and CO with trans-Pacific transported or North American air masses relative to the Pacific background. Mean values of the enhancements for March to June were 6 ppbv and 16 ppbv for O3 and CO respectively. In summers 2002–2006, higher CO and O3 mixing ratios were always observed in North American air masses and this relative enhancement co-varied for each year with the western US and Canada total wildfire area. The greatest enhancements in O3 and CO were seen in 2004, a record year for forest fires in Alaska and the Yukon Territory. In August 2004, average O3 and CO mixing ratios were 13 and 44 ppbv above background values.

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Cross-validation of inferred daytime airborne CO<sub>2</sub> urban-regional scale surface fluxes with eddy-covariance observations and emissions inventories in Greater London

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-13-13465-2013 ◽

2013 ◽

Vol 13 (5) ◽

pp. 13465-13493 ◽

Cited By ~ 3

Author(s):

A. Font ◽

C. S. B. Grimmond ◽

J.-A. Morguí ◽

S. Kotthaus ◽

M. Priestman ◽

...

Keyword(s):

Eddy Covariance ◽

Urban Areas ◽

Cross Validation ◽

Regional Scale ◽

Co2 Flux ◽

Surface Fluxes ◽

Co2 Fluxes ◽

Wind Speeds ◽

Mixing Ratios ◽

Emissions Inventories

Abstract. Data obtained from eleven flight surveys on six days during October 2011 were used to characterize the urban CO2 dome in Greater London (GL) and to calculate CO2 fluxes at the city scale. Flights crossed GL along two transects (SW-NE and SSE-NNW) at an altitude of 360 m. Increments as high as 23 ppmv were measured. The maximum CO2 mixing ratios were localized over GL under low wind speeds, whereas a displacement of the urban plume downwind from the centre of the urban area occurred during high wind speeds. The urban-regional surface CO2 flux was calculated for four days by the Integrative Mass Boundary Layer (IMBL) method. The diurnal CO2 flux in GL obtained from the aircraft observations ranged from 46 to 104 μmol CO2 m−2 s−1 during the day time. The mean CO2 fluxes estimated from the IMBL method were statistically similar to those observed by eddy-covariance systems located in central London and a spatially integrated emissions inventory for GL. This study provides an important cross-validation of two independent measurement-based methods to infer the contribution of urban areas to climate change in terms of CO2 surface fluxes, both of which complement bottom-up emissions inventories. The uncertainties of fluxes estimated by the IMBL method are considered and the limits of implementation of atmospheric methods to infer city-scale fluxes are discussed.

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The influence of typhoons on atmospheric composition deduced from IAGOS measurements over Taipei

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-3945-2020 ◽

2020 ◽

Vol 20 (6) ◽

pp. 3945-3963

Author(s):

Frank Roux ◽

Hannah Clark ◽

Kuo-Ying Wang ◽

Susanne Rohs ◽

Bastien Sauvage ◽

...

Keyword(s):

Carbon Monoxide ◽

Relative Humidity ◽

Tropical Cyclones ◽

Marine Boundary Layer ◽

Chemical Species ◽

Atmospheric Composition ◽

Commercial Aircraft ◽

Regular Feature ◽

Mixing Ratios ◽

The Vertical Distribution

Abstract. The research infrastructure IAGOS (In-Service Aircraft for a Global Observing System) equips commercial aircraft with instruments to monitor the composition of the atmosphere during flights around the world. In this article, we use data from two China Airlines aircraft based in Taipei (Taiwan) which provided daily measurements of ozone, carbon monoxide and water vapour throughout the summer of 2016. We present time series, from the surface to the upper troposphere, of ozone, carbon monoxide and relative humidity near Taipei, focusing on periods influenced by the passage of typhoons. We examine landing and take-off profiles in the vicinity of tropical cyclones using ERA-5 reanalyses to elucidate the origin of the anomalies in the vertical distribution of these chemical species. Results indicate a high ozone content in the upper- to middle-troposphere track of the storms. The high ozone mixing ratios are generally correlated with potential vorticity and anti-correlated with relative humidity, suggesting stratospheric origin. These results suggest that tropical cyclones participate in transporting air from the stratosphere to troposphere and that such transport could be a regular feature of typhoons. After the typhoons passed Taiwan, the tropospheric column was filled with substantially lower ozone mixing ratios due to the rapid uplift of marine boundary layer air. At the same time, the relative humidity increased, and carbon monoxide mixing ratios fell. Locally, therefore, the passage of typhoons has a positive effect on air quality at the surface, cleansing the atmosphere and reducing the mixing ratios of pollutants such as CO and O3.

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Pan-Arctic aerosol number size distributions: seasonality and transport patterns

Atmospheric Chemistry and Physics ◽

10.5194/acp-17-8101-2017 ◽

2017 ◽

Vol 17 (13) ◽

pp. 8101-8128 ◽

Cited By ~ 33

Author(s):

Eyal Freud ◽

Radovan Krejci ◽

Peter Tunved ◽

Richard Leaitch ◽

Quynh T. Nguyen ◽

...

Keyword(s):

Arctic Ocean ◽

Regional Scale ◽

Arctic Region ◽

The Arctic ◽

Research Station ◽

Size Distributions ◽

Back Trajectories ◽

Accumulation Mode ◽

Source Regions ◽

The Arctic Ocean

Abstract. The Arctic environment has an amplified response to global climatic change. It is sensitive to human activities that mostly take place elsewhere. For this study, a multi-year set of observed aerosol number size distributions in the diameter range of 10 to 500 nm from five sites around the Arctic Ocean (Alert, Villum Research Station – Station Nord, Zeppelin, Tiksi and Barrow) was assembled and analysed.A cluster analysis of the aerosol number size distributions revealed four distinct distributions. Together with Lagrangian air parcel back-trajectories, they were used to link the observed aerosol number size distributions with a variety of transport regimes. This analysis yields insight into aerosol dynamics, transport and removal processes, on both an intra- and an inter-monthly scale. For instance, the relative occurrence of aerosol number size distributions that indicate new particle formation (NPF) event is near zero during the dark months, increases gradually to ∼ 40 % from spring to summer, and then collapses in autumn. Also, the likelihood of Arctic haze aerosols is minimal in summer and peaks in April at all sites.The residence time of accumulation-mode particles in the Arctic troposphere is typically long enough to allow tracking them back to their source regions. Air flow that passes at low altitude over central Siberia and western Russia is associated with relatively high concentrations of accumulation-mode particles (Nacc) at all five sites – often above 150 cm−3. There are also indications of air descending into the Arctic boundary layer after transport from lower latitudes.The analysis of the back-trajectories together with the meteorological fields along them indicates that the main driver of the Arctic annual cycle of Nacc, on the larger scale, is when atmospheric transport covers the source regions for these particles in the 10-day period preceding the observations in the Arctic. The scavenging of these particles by precipitation is shown to be important on a regional scale and it is most active in summer. Cloud processing is an additional factor that enhances the Nacc annual cycle.There are some consistent differences between the sites that are beyond the year-to-year variability. They are the result of differences in the proximity to the aerosol source regions and to the Arctic Ocean sea-ice edge, as well as in the exposure to free-tropospheric air and in precipitation patterns – to mention a few. Hence, for most purposes, aerosol observations from a single Arctic site cannot represent the entire Arctic region. Therefore, the results presented here are a powerful observational benchmark for evaluation of detailed climate and air chemistry modelling studies of aerosols throughout the vast Arctic region.

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Regional Scale Impact of the COVID-19 Lockdown on Air Quality: Gaseous Pollutants in the Po Valley, Northern Italy

Atmosphere ◽

10.3390/atmos12020264 ◽

2021 ◽

Vol 12 (2) ◽

pp. 264 ◽

Cited By ~ 1

Author(s):

Giovanni Lonati ◽

Federico Riva

Keyword(s):

Air Quality ◽

Urban Areas ◽

Regional Scale ◽

High Volume ◽

Ambient Air ◽

Northern Italy ◽

Traffic Emissions ◽

Gaseous Pollutants ◽

Po Valley ◽

Concentration Levels

The impact of the reduced atmospheric emissions due to the COVID-19 lockdown on ambient air quality in the Po Valley of Northern Italy was assessed for gaseous pollutants (NO2, benzene, ammonia) based on data collected at the monitoring stations distributed all over the area. Concentration data for each month of the first semester of 2020 were compared with those of the previous six years, on monthly, daily, and hourly bases, so that pre, during, and post-lockdown conditions of air quality could be separately analyzed. The results show that, as in many other areas worldwide, the Po Valley experienced better air quality during 2020 spring months for NO2 and benzene. In agreement with the reductions of nitrogen oxides and benzene emissions from road traffic, estimated to be −35% compared to the regional average, the monthly mean concentration levels for 2020 showed reductions in the −40% to −35% range compared with the previous years, but with higher reductions, close to −50%, at high-volume-traffic sites in urban areas. Conversely, NH3 ambient concentration levels, almost entirely due the emissions of the agricultural sector, did not show any relevant change, even at high-volume-traffic sites in urban areas. These results point out the important role of traffic emissions in NO2 and benzene ambient levels in the Po Valley, and confirm that this region is a rather homogeneous air basin with urban area hot-spots, the contributions of which add up to a relatively high regional background concentration level. Additionally, the relatively slow response of the air quality levels to the sudden decrease of the emissions due to the lockdown shows that this region is characterized by a weak exchange of the air masses that favors both the build-up of atmospheric pollutants and the development of secondary formation processes. Thus, air quality control strategies should aim for structural interventions intended to reduce traffic emissions at the regional scale and not only in the largest urban areas.

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Contribution of Local and Transboundary Air Pollution to the Urban Air Quality of Fukuoka, Japan

Atmosphere ◽

10.3390/atmos12040431 ◽

2021 ◽

Vol 12 (4) ◽

pp. 431

Author(s):

Ayako Yoshino ◽

Akinori Takami ◽

Keiichiro Hara ◽

Chiharu Nishita-Hara ◽

Masahiko Hayashi ◽

...

Keyword(s):

Air Pollution ◽

Air Quality ◽

Urban Areas ◽

Air Pollutants ◽

Regional Scale ◽

Gaseous Species ◽

Transboundary Air Pollution ◽

Local Air Pollution ◽

The City

Transboundary air pollution (TAP) and local air pollution (LAP) influence the air quality of urban areas. Fukuoka, located on the west side of Japan and affected by TAP from the Asian continent, is a unique example for understanding the contribution of LAP and TAP. Gaseous species and particulate matter (PM) were measured for approximately three weeks in Fukuoka in the winter of 2018. We classified two distinctive periods, LAP and TAP, based on wind speed. The classification was supported by variations in the concentration of gaseous species and by backward trajectories. Most air pollutants, including NOx and PM, were high in the LAP period and low in the TAP period. However, ozone was the exception. Therefore, our findings suggest that reducing local emissions is necessary. Ozone was higher in the TAP period, and the variation in ozone concentration was relatively small, indicating that ozone was produced outside of the city and transported to Fukuoka. Thus, air pollutants must also be reduced at a regional scale, including in China.

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