scholarly journals Temporal variations of black carbon in Guangzhou, China, in summer 2006

2010 ◽  
Vol 10 (14) ◽  
pp. 6471-6485 ◽  
Author(s):  
R. L. Verma ◽  
L. K. Sahu ◽  
Y. Kondo ◽  
N. Takegawa ◽  
S. Han ◽  
...  
Keyword(s):  
Black Carbon ◽  
Temporal Variations ◽  
Back Trajectories ◽  
Air Masses ◽  
Mixing Ratios ◽  
Diurnal Patterns ◽  
Air Mass Types ◽  
The Pearl River ◽  
Carbon Dioxide Co2 ◽  
Marine Air

Abstract. In situ measurements of the mass concentration of black carbon (BC) and mixing ratios of carbon monoxide (CO) and carbon dioxide (CO2) were made at Guangzhou, an urban measurement site in the Pearl River Delta (PRD), China, in July 2006. The average ± standard deviation (SD) concentrations of BC, CO, and CO2 were 4.7± 2.3 μgC m−3, 798± 459 ppbv, and 400± 13 ppmv, respectively. The trends of these species were mainly controlled by synoptic-scale changes in meteorology during the campaign. Based on back trajectories, data are analyzed separately for two different air mass types representing northerly and southerly flows. The northerly air masses, which constituted ~25% of the campaign, originated mostly in the PRD and hence represent observations on regional scales. On the other hand, during southerly flow (~75%), the measurements were influenced by dilution due to cleaner marine air. The diurnal patterns of BC, CO, and CO2 exhibited peak concentrations during the morning and evening hours coinciding with rush-hour traffic. The ratios of OC/BC were lower during the morning hour peaks in the concentrations of primary pollutants due to their fresh emissions mainly from vehicular traffic in Guangzhou. The diurnal variations of BC observed in southerly air masses tended to follow the traffic patterns of heavy-duty vehicles (HDV) in Guangzhou, while the roles of other sources need to be investigated. The slopes of ΔBC/ΔCO, ΔBC/ΔCO2, and ΔCO/ΔCO2 observed during northerly flows were 0.0045 μgC m−3/ppbv, 0.13 μgC m−3/ppmv, and 49.4 ppbv/ppmv, respectively, agreeing reasonably with their respective emission ratios derived from regional emission inventories.

scholarly journals Temporal variation of elemental carbon in Guangzhou, China, in summer 2006

2009 ◽  
Vol 9 (6) ◽  
pp. 24629-24667 ◽  
Author(s):  
R. L. Verma ◽  
L. K. Sahu ◽  
Y. Kondo ◽  
N. Takegawa ◽  
S. Han ◽  
...  
Keyword(s):  
Elemental Carbon ◽  
Back Trajectories ◽  
Air Masses ◽  
Traffic Pattern ◽  
Mixing Ratios ◽  
Diurnal Patterns ◽  
Air Mass Types ◽  
The Pearl River ◽  
Carbon Dioxide Co2 ◽  
Marine Air

Abstract. In situ measurements of the mass concentration of elemental carbon (EC) and mixing ratios of carbon monoxide (CO) and carbon dioxide (CO2) were made at Guangzhou, an urban measurement site in the Pearl River Delta (PRD), China, in July 2006. The average±standard deviation (SD) concentrations of EC, CO, and CO2 were 4.7±2.3 μg C m−3, 798±459 ppbv and 400±13 ppmv, respectively. The trends of these species were mainly controlled by synoptic-scale changes in meteorology during the campaign. Based on back trajectories, data are analyzed separately for two different air mass types representing northerly and southerly flows. Northerly air masses, constituting about 25% of the campaign, were mainly impacted by stagnant conditions, resulting in elevated levels of pollutants. On the other hand, southerly air masses measured during most of the campaign were mostly influenced by clean marine air. The diurnal patterns of EC, CO, and CO2 exhibited peak concentrations during the morning and evening hours coinciding with rush-hour traffic. The diurnal variations of EC and ΔEC/ΔCO closely followed the traffic pattern of heavy-duty vehicles (HDV) in Guangzhou, similar to that observed in Beijing. The level of EC in this campaign was similar to values reported during previous studies at other sites surrounding Guangzhou. The average slopes of ΔEC/ΔCO, ΔEC/ΔCO2, and ΔCO/ΔCO2 were 0.0054 μg C m−3/ppbv, 0.15 μg C m−3/ppmv, and 46.4 ppbv/ppmv, respectively, agreeing reasonably well with their respective emission ratios derived from regional emission inventories.

scholarly journals Continuous atmospheric CO<sub>2</sub>, CH<sub>4</sub> and CO measurements at the OPE station in France from 2011 to 2018

2019 ◽  
Author(s):  
Sébastien Conil ◽  
Julie Helle ◽  
Laurent Langrene ◽  
Olivier Laurent ◽  
Michel Ramonet
Keyword(s):  
Greenhouse Gases ◽  
Observation System ◽  
Atmospheric Concentration ◽  
Close Link ◽  
Back Trajectories ◽  
Air Masses ◽  
Mixing Ratios ◽  
North East ◽  
The North ◽  
Carbon Dioxide Co2

Abstract. Located in the North East of France, the Observatoire Pérenne de l'Environnement (OPE) station was built during the Integrated Carbon Observation System (ICOS) Demonstration Experiment to monitor the atmospheric concentration of greenhouse gases. Its continental rural background setting allows to fill the gaps between oceanic or mountain background stations and urban stations within the ICOS network. Continuous measurements of several greenhouse gases using high precision spectrometers started in 2011 on a tall tower with three sampling inlets at 10 m, 50 m and 120 m above the ground. The measurements quality are regularly assessed using several complementary approaches based on reference high pressure cylinders, traveling instruments audit and sets of travelling cylinders (so-called cucumber intercomparison). Thanks to the quality assurance strategy recommended by ICOS, the measurements precision are within the WMO compatibility goals for carbon dioxide (CO2), methane (CH4) and carbon monoxide (CO). The mixing ratios time series from 2011 to end of 2018 allow analyses of trends and diurnal and seasonal cycles. The CO2 and CH4 annual growth rates are respectively 2.4 ppm/year and 8.8 ppb/year for the 120 m above ground measurements over the investigated period. No significant trend has however been recorded for the CO mixing ratios. The afternoon mean residuals of these three compounds are significantly stronger during the cold period when inter-species correlations are high, compared to the warm period. The residuals variabilities show a close link with the air masses back-trajectories.

scholarly journals Quantifying black carbon light absorption enhancement by a novel statistical approach

2017 ◽  
Author(s):  
Cheng Wu ◽  
Dui Wu ◽  
Jian Zhen Yu
Keyword(s):  
Black Carbon ◽  
Light Absorption ◽  
Seasonal Pattern ◽  
Absorption Efficiency ◽  
Absorption Enhancement ◽  
Hygroscopic Growth ◽  
Pearl River Delta Region ◽  
Coating Materials ◽  
Air Masses ◽  
The Pearl River

Abstract. Black carbon (BC) particles in the atmosphere can absorb more light when coated by non-absorbing or weakly absorbing materials during atmospheric aging, due to the lensing effect. In this study, the light absorption enhancement factor, Eabs, was quantified using one year's measurement of mass absorption efficiency (MAE) in the Pearl River Delta region (PRD). A new approach for calculating primary MAE (MAEp), the key for Eabs estimation, is demonstrated using the Minimum R Squared (MRS) method, exploring the inherent source independency between BC and its coating materials. The annual average Eabs is found to be 1.52, exhibiting a clear seasonal pattern with higher values in summer and lower in the winter. Elevated Eabs in the rainy summer season is likely associated with aged air masses dominating from marine origin, along with long-range transport of biomass burning influenced air masses from Southeast Asia. Eabs induced by hygroscopic growth at elevated RH could be as high as 1.3. Core-shell Mie simulations along with measured Eabs and Angstrom absorption exponent (AAE) constraints suggest that in the PRD, the coating materials are unlikely to be dominated by brown carbon and the coating thickness is higher in the rainy season than the dry season. A negative correlation is found between AAE470–660 and RH, suggesting a dominant particle size of Dcore = 130 nm and Dshell/Dcore range of 2 to 4.

scholarly journals Airborne observations and modeling of springtime stratosphere-to-troposphere transport over California

2013 ◽  
Vol 13 (4) ◽  
pp. 10157-10192 ◽  
Author(s):  
E. L. Yates ◽  
L. T. Iraci ◽  
M. C. Roby ◽  
R. B. Pierce ◽  
M. S. Johnson ◽  
...  
Keyword(s):  
Air Quality ◽  
Free Troposphere ◽  
Air Mass ◽  
Air Masses ◽  
Airborne Measurements ◽  
Mixing Ratios ◽  
Stratospheric Intrusion ◽  
Tropospheric O3 ◽  
Carbon Dioxide Co2 ◽  
The Impact

Abstract. Stratosphere-to-troposphere transport (STT) results in air masses of stratospheric origin intruding into the free troposphere. Once in the free troposphere, O3-rich stratospheric air can be transported and mixed with tropospheric air masses, contributing to the tropospheric O3 budget. Evidence of STT can be identified based on the differences in the trace gas composition of the two regions. Because ozone (O3) is present in such large quantities in the stratosphere compared to the troposphere, it is frequently used as a tracer for STT events. This work reports on airborne in situ measurements of O3 and other trace gases during two STT events observed over California, USA. The first, on 14 May 2012, was associated with a cut-off low, and the second, on 5 June 2012, occurred during a post-trough, building ridge event. In each STT event, airborne measurements identified high O3 within a stratospheric intrusion which was observed as low as 3 km above sea level. During both events the stratospheric air mass was characterized by elevated O3 mixing ratios and reduced carbon dioxide (CO2) and water vapor. The reproducible observation of reduced CO2 within the stratospheric air mass supports the use of non-conventional tracers as an additional method for detecting STT. A detailed meteorological analysis of each STT event is presented and observations are interpreted with the Realtime Air Quality Modeling System (RAQMS). The implications of the two STT events are discussed in terms of the impact on the total tropospheric O3 budget and the impact on air quality and policy-making.

scholarly journals Atmospheric bromoform at Cape Point, South Africa: a first time series on the African continent

2017 ◽  
Author(s):  
Brett Kuyper ◽  
Carl J. Palmer ◽  
Casper Labuschagne ◽  
Chris J. C. Reason
Keyword(s):  
South Africa ◽  
Austral Spring ◽  
Data Set ◽  
Air Masses ◽  
Mixing Ratios ◽  
Front End ◽  
Potential Source ◽  
High Concentrations ◽  
Marine Air ◽  
First Time

Abstract. Bromoform mixing ratios in marine air were measured at Cape Point Global Atmospheric Watch Station, South Africa. This represents the first ever bromoform data set recorded at this unique location. Manual daily measurements were made during a month long field campaign (austral spring 2011) using a GC-ECD with a custom built front end thermal desorption trap. The measured concentrations ranged between 2.3 ± 0.4 and 84.7 ± 10.8 ppt with a mean of 24.7 ± 3.1 ppt. Our analysis shows the concentration of bromform varies significantly according to wind direction and the trajectory of the air mass sampled. Air masses which had come into contact with multiple potential source of bromoform showed the highest average mixing ratios. The measurements reported here represent some of the highest recorded coastal bromoform concentrations globally. These high concentrations may be explained by the multiple local sources of bromoform around Cape Point.

scholarly journals Variability of aerosol, gaseous pollutants and meteorological characteristics associated with changes in air mass origin at the SW Atlantic coast of Iberia

2012 ◽  
Vol 12 (8) ◽  
pp. 3761-3782 ◽  
Author(s):  
J.-M. Diesch ◽  
F. Drewnick ◽  
S. R. Zorn ◽  
S.-L. von der Weiden-Reinmüller ◽  
M. Martinez ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
Gas Phase ◽  
Organic Aerosol ◽  
Research Station ◽  
Air Mass ◽  
Air Masses ◽  
Air Mass Types ◽  
Marine Air ◽  
The Impact ◽  
Air Mass Origin

Abstract. Measurements of the ambient aerosol were performed at the Southern coast of Spain, within the framework of the DOMINO (Diel Oxidant Mechanisms In relation to Nitrogen Oxides) project. The field campaign took place from 20 November until 9 December 2008 at the atmospheric research station "El Arenosillo" (37°5'47.76" N, 6°44'6.94" W). As the monitoring station is located at the interface between a natural park, industrial cities (Huelva, Seville) and the Atlantic Ocean, a variety of physical and chemical parameters of aerosols and gas phase could be characterized in dependency on the origin of air masses. Backwards trajectories were examined and compared with local meteorology to classify characteristic air mass types for several source regions. Aerosol number and mass as well as polycyclic aromatic hydrocarbons and black carbon concentrations were measured in PM1 and size distributions were registered covering a size range from 7 nm up to 32 μm. The chemical composition of the non-refractory submicron aerosol (NR-PM1) was measured by means of an Aerosol Mass Spectrometer (Aerodyne HR-ToF-AMS). Gas phase analyzers monitored various trace gases (O3, SO2, NO, NO2, CO2) and a weather station provided meteorological parameters. Lowest average submicron particle mass and number concentrations were found in air masses arriving from the Atlantic Ocean with values around 2 μg m−3 and 1000 cm−3. These mass concentrations were about two to four times lower than the values recorded in air masses of continental and urban origins. For some species PM1-fractions in marine air were significantly larger than in air masses originating from Huelva, a closely located city with extensive industrial activities. The largest fraction of sulfate (54%) was detected in marine air masses and was to a high degree not neutralized. In addition, small concentrations of methanesulfonic acid (MSA), a product of biogenic dimethyl sulfate (DMS) emissions, could be identified in the particle phase. In all air masses passing the continent the organic aerosol fraction dominated the total NR-PM1. For this reason, using Positive Matrix Factorization (PMF) four organic aerosol (OA) classes that can be associated with various aerosol sources and components were identified: a highly-oxygenated OA is the major component (43% OA) while semi-volatile OA accounts for 23%. A hydrocarbon-like OA mainly resulting from industries, traffic and shipping emissions as well as particles from wood burning emissions also contribute to total OA and depend on the air mass origin. A significant variability of ozone was observed that depends on the impact of different air mass types and solar radiation.

scholarly journals Size-resolved observations of refractory black carbon particles in cloud droplets at a marine boundary layer site

2014 ◽  
Vol 14 (8) ◽  
pp. 11447-11491 ◽  
Author(s):  
J. C. Schroder ◽  
S. J. Hanna ◽  
R. L. Modini ◽  
A. L. Corrigan ◽  
A. M. Macdonald ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Black Carbon ◽  
Marine Boundary Layer ◽  
Back Trajectory ◽  
Cloud Droplets ◽  
Back Trajectories ◽  
Air Masses ◽  
Carbon Particles ◽  
Back Trajectory Analysis ◽  
La Jolla

Abstract. Size resolved observations of aerosol particles (including black carbon particles) and cloud residuals were studied at a marine boundary layer site (251 m a.m.s.l.) in La Jolla, CA during 2012. A counterflow virtual impactor was used to sample cloud residuals while a total inlet was used to sample both cloud residuals and interstitial particles. Two cloud events totaling ten hours of in-cloud sampling were analyzed. Since the CVI only sampled cloud droplets larger than &amp;approx;11 μm, less than 100% of the cloud droplets were sampled during the two cloud events (&amp;approx;38% of the cloud droplets for the first cloud event and &amp;approx;24% of the cloud droplets for the second cloud were sampled). Back trajectories showed that air masses for both cloud events spent at least 96 h over the Pacific Ocean and traveled near, or over populated regions just before sampling. Based on bulk aerosol particle concentrations measured from the total inlet the two air masses sampled were classified as polluted marine air, a classification that was consistent with back trajectory analysis and the mass concentrations of refractory black carbon (rBC) measured from the total inlet. The activated fraction of rBC, estimated from the measurements, ranged from 0.01 to 0.1 for core diameters ranging from 70 to 220 nm. Since the fraction of cloud droplets sampled by the CVI was less than 100%, the measured activated fractions of rBC should be considered as lower limits to the total fraction of rBC activated during the two cloud events. Size distributions of rBC sampled from the residual inlet show that sub-100 nm rBC cores were incorporated into the droplets in both clouds. The coating analysis shows that the rBC cores had average coating thicknesses of 75 nm for core diameters of 70 nm and 29 nm for core diameters of 220 nm. The presence of sub-100 nm rBC cores in the cloud residuals is consistent with kappa-Köhler theory and the measured coating thicknesses of the rBC cores.

scholarly journals Alteration of the microphysical properties of black carbon through transport in the boundary layer in East Asia

2016 ◽  
Author(s):  
Takuma Miyakawa ◽  
Naga Oshima ◽  
Fumikazu Taketani ◽  
Yuichi Komazaki ◽  
Ayako Yoshino ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Black Carbon ◽  
Water Solubility ◽  
Southern China ◽  
Cloud Condensation Nuclei ◽  
Source Region ◽  
Temporal Variations ◽  
Early Summer ◽  
Air Masses ◽  
Remote Island

Abstract. Ground-based measurements of black carbon (BC) were performed near an industrial source region in the early summer of 2014 and at a remote island in Japan in the spring of 2015. We report the temporal variations in the transport, size distributions, and mixing states of the BC-containing particles measured using a continuous soot monitoring system, a single particle soot photometer, and an aerosol chemical speciation monitor. The effects of aging on the growth of BC-containing particles were examined by comparing the ground-based observations between the near-source and remote island sites. Secondary formation of sulfate aerosol through gas- and cloud-phase reactions strongly affected the increases in BC coating (i.e., enhancement of cloud condensation nuclei activity) with air mass aging from the source to the outflow regions. The effects of the wet removal on the BC microphysics were elucidated by classifying the continental outflow air masses depending on the enhancement ratio of BC to CO (ΔBC / ΔCO) ratios as an indicator of the transport efficiency of BC. It was found that ΔBC / ΔCO ratios were controlled mainly by the rainout process during transport in the planetary boundary layer (PBL) on the timescale of 1–2 days. The meteorological conditions and backward trajectory analyses suggested that air masses strongly affected by rainout originated mainly from Southern China region (20º–35º N) during this season. Selective removal of large and thickly-coated BC-containing particles was found in air masses substantially affected by the rainout in the PBL, as predicted by Köhler theory. The size and water-solubility of BC-containing particles in the PBL can be altered by the rainout process as well as the condensation of non-BC materials.

scholarly journals Trace gas composition in the Asian summer monsoon anticyclone: A case study based on aircraft observations and model simulations

2016 ◽  
Author(s):  
Klaus-D. Gottschaldt ◽  
Hans Schlager ◽  
Robert Baumann ◽  
Heiko Bozem ◽  
Veronika Eyring ◽  
...  
Keyword(s):  
Summer Monsoon ◽  
Atmospheric Chemistry ◽  
Asian Summer Monsoon ◽  
Trace Gas ◽  
Gas Composition ◽  
Back Trajectories ◽  
Air Masses ◽  
Mixing Ratios ◽  
Asian Summer

Abstract. We present in-situ measurements of the trace gas composition of the upper tropospheric (UT) Asian summer monsoon anticyclone (ASMA) performed with the High Altitude and LOng range (HALO) research aircraft in the frame of the Earth System Model Validation (ESMVal) campaign. Air masses with enhanced O3 mixing ratios were encountered after entering the ASMA at its southern edge at about 150 hPa on 18 September 2012. This is in contrast to previous studies, reporting that the anticyclone's interior is dominated by recently uplifted air with low O3 in the monsoon season. We also observed enhanced CO and HCl in the ASMA, tracers for boundary layer pollution and tropopause layer (TL) air or stratospheric inmixing, respectively. In addition, reactive nitrogen was enhanced in the ASMA. Along the HALO flight track across the ASMA boundary, strong gradients of these tracers separate anticyclonic from outside air. Lagrangian trajectory calculations using HYSPLIT show that HALO sampled three times a filament of UT air, which included air masses uplifted from the lower or mid troposphere north of the Bay of Bengal. The trace gas gradients between UT and uplifted air masses were preserved during transport within a belt of streamlines fringing the central part of the anticyclone (fringe), but are smaller than the gradients across the ASMA boundary. Our data represent the first in-situ observations across the southern and downstream the eastern ASMA flank, respectively. Back-trajectories starting at the flight track furthermore indicate that HALO transected the ASMA where it was just splitting into a Tibetan and an Iranian part. The O3-rich filament is diverted from the fringe towards the interior of the original anticyclone, and at least partially bound to become part of the new Iranian eddy. A simulation with the ECHAM/MESSy Atmospheric Chemistry (EMAC) model is found to reproduce the observations reasonably well. It shows that O3-rich air is entrained by the outer streamlines of the anticyclone at its eastern flank. Back-trajectories and increased HCl mixing ratios indicate that the entrained air originates in the stratospherically influenced TL. Photochemical ageing of air masses in the ASMA additionally increases O3 in originally O3-poor, but CO-rich air. Simulated monthly mean trace gas distributions show decreased O3 in the ASMA centre not in general, but only at the 100 hPa level in July and August, as also reported by previous studies. However, at lower altitudes and in September the ASMA is dominated by increased O3, indicating that the above processes are more important for the ASMA trace gas budgets than previously thought.

scholarly journals Airborne observations and modeling of springtime stratosphere-to-troposphere transport over California

2013 ◽  
Vol 13 (24) ◽  
pp. 12481-12494 ◽  
Author(s):  
E. L. Yates ◽  
L. T. Iraci ◽  
M. C. Roby ◽  
R. B. Pierce ◽  
M. S. Johnson ◽  
...  
Keyword(s):  
Air Quality ◽  
Free Troposphere ◽  
Air Mass ◽  
Air Masses ◽  
Airborne Measurements ◽  
Mixing Ratios ◽  
Stratospheric Intrusion ◽  
Tropospheric O3 ◽  
Carbon Dioxide Co2 ◽  
The Impact

Abstract. Stratosphere-to-troposphere transport (STT) results in air masses of stratospheric origin intruding into the free troposphere. Once in the free troposphere, ozone (O3)-rich stratospheric air can be transported and mixed with tropospheric air masses, contributing to the tropospheric O3 budget. Evidence of STT can be identified based on the differences in the trace gas composition of the two regions. Because O3 is present in such large quantities in the stratosphere compared to the troposphere, it is frequently used as a tracer for STT events. This work reports on airborne in situ measurements of O3 and other trace gases during two STT events observed over California, USA. The first, on 14 May 2012, was associated with a cutoff low, and the second, on 5 June 2012, occurred during a post-trough, building ridge event. In each STT event, airborne measurements identified high O3 within the stratospheric intrusion, which were observed as low as 3 km above sea level. During both events the stratospheric air mass was characterized by elevated O3 mixing ratios and reduced carbon dioxide (CO2) and water vapor. The reproducible observation of reduced CO2 within the stratospheric air mass supports the use of non-conventional tracers as an additional method for detecting STT. A detailed meteorological analysis of each STT event is presented, and observations are interpreted with the Realtime Air Quality Modeling System (RAQMS). The implications of the two STT events are discussed in terms of the impact on the total tropospheric O3 budget and the impact on air quality and policy-making.

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