scholarly journals Effects of black carbon and boundary layer interaction on surface ozone in Nanjing, China

2018 ◽  
Author(s):  
Jinhui Gao ◽  
Bin Zhu ◽  
Hui Xiao ◽  
Hanqing Kang ◽  
Chen Pan
Keyword(s):  
Boundary Layer ◽  
Black Carbon ◽  
Physical Process ◽  
Surface Ozone ◽  
Vertical Mixing ◽  
Ozone Pollution ◽  
Model Studies ◽  
Photolysis Rate ◽  
Boundary Layer Interaction ◽  
Physical And Chemical

Abstract. As an important solar-radiation absorbing aerosol, the effect of black carbon (BC) on surface ozone, by influencing photolysis rate, has been widely discussed by offline model studies. However, BC-boundary layer (BL) interactions also influence surface ozone. Using the online model simulations and processes analysis, we demonstrate the significant impact of BC-BL interaction on surface ozone. The absorbing effect of BC heats the air above the BL and suppresses BL development, which eventually leads to changes in the contributions of ozone through chemical and physical processes (photochemistry, vertical mixing, and advection). Different from previous offline model studies, BL suppression leads large amounts of ozone precursors being confined below the BL which offsetting the influence from the reduction of photolysis rate, thus enhancing ozone photochemical formation before noon. Furthermore, the changes in physical process show a more significant influence on surface ozone. The weakened turbulence entrains much less ozone from the overlying ozone-rich air down to surface. As a result, the net contribution of ozone from physical and chemical processes leads to surface ozone reduction before noon. The maximum reduction reaches to 16.4 ppb at 12:00. In the afternoon, the changes in chemical process are small which influence inconspicuously to surface ozone. However, physical process still influences the surface ozone significantly. Due to the delayed development of the BL, less vertically mixed BL continues to show an obvious ozone gradient near the top of the BL. Therefore, more ozone aloft can be entrained down to the surface, offsetting the surface ozone reduction. Comparing all the changes in the contributions of processes, the change in the contribution of vertical mixing plays a more important role in impacting surface ozone. Our results show the great impacts of BC-BL interactions on surface ozone. And more attention should be paid on the mechanism of aerosol-BL interactions when we deal with the ozone pollution control in China.

scholarly journals Effects of black carbon and boundary layer interaction on surface ozone in Nanjing, China

2018 ◽  
Vol 18 (10) ◽  
pp. 7081-7094 ◽  
Author(s):  
Jinhui Gao ◽  
Bin Zhu ◽  
Hui Xiao ◽  
Hanqing Kang ◽  
Chen Pan ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Black Carbon ◽  
Process Analysis ◽  
Surface Ozone ◽  
Vertical Mixing ◽  
Mixing Process ◽  
Ozone Pollution ◽  
Chemical Production ◽  
Physical Processes ◽  
Photolysis Rate

Abstract. As an important solar radiation absorbing aerosol, the effect of black carbon (BC) on surface ozone, via reducing photolysis rate, has been widely discussed by “offline” model studies. However, BC–boundary layer (BL) interactions also influence surface ozone. Using the “online” model simulations and process analysis, we demonstrate the significant impact of BC–BL interaction on surface ozone in Nanjing. The absorbing effect of BC heats the air above the BL and suppresses and delays the development of the BL, which eventually leads to a change in surface ozone via a change in the contributions from chemical and physical processes (photochemistry, vertical mixing and advection). For chemical processes, the suppression of the BL leads to large amounts of ozone precursors being confined below the BL which has an increased effect on ozone chemical production and offsets the decrease caused by the reduction of the photolysis rate, thus enhancing ozone chemical formation from 10:00 to 12:00 LT. Furthermore, changes in physical processes, especially the vertical mixing process, show a more significant influence on surface ozone. The weakened turbulence, caused by the suppressed BL, entrains much less ozone aloft down to the surface. Finally, summing-up the changes in the processes, surface ozone reduces before noon and the maximum reduction reaches 16.4 ppb at 12:00 LT. In the afternoon, the changes in chemical process are small which inconspicuously influence surface ozone. However, change in the vertical mixing process still influences surface ozone significantly. Due to the delayed development of the BL, there are obvious ozone gradients around the top of BL. Therefore, high concentrations of ozone aloft can still be entrained down to the surface which offsets the reduction of surface ozone. Comparing the changes in the processes, the change in vertical mixing plays the most important role in impacting surface ozone. Our results highlight the great impacts BC–BL interactions have on surface ozone by influencing the ozone contribution from physical process. This suggests that more attention should be paid to the mechanism of aerosol–BL interactions when controlling ozone pollution.

scholarly journals NO<sub>x</sub> emissions, isoprene oxidation pathways, vertical mixing, and implications for surface ozone in the Southeast United States

2016 ◽  
Author(s):  
Katherine R. Travis ◽  
Daniel J. Jacob ◽  
Jenny A. Fisher ◽  
Patrick S. Kim ◽  
Eloise A. Marais ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Surface Ozone ◽  
Vertical Mixing ◽  
Satellite Observations ◽  
Oxidation Products ◽  
Large Contribution ◽  
Nox Emissions ◽  
Tropospheric No2 ◽  
Isoprene Oxidation ◽  
Southeast Us

Abstract. Ozone pollution in the Southeast US involves complex chemistry driven by emissions of anthropogenic nitrogen oxide radicals (NOx ≡ NO + NO2) and biogenic isoprene. Model estimates of surface ozone concentrations tend to be biased high in the region and this is of concern for designing effective emission control strategies to meet air quality standards. We use detailed chemical observations from the SEAC4RS aircraft campaign in August and September 2013, interpreted with the GEOS-Chem chemical transport model (CTM) at 0.25°×0.3125° horizontal resolution, to better understand the factors controlling surface ozone in the Southeast US. We find that the National Emission Inventory (NEI) for NOx from the US Environmental Protection Agency (EPA) is too high in the Southeast and nationally by 50 %. This is demonstrated by SEAC4RS observations of NOx and its oxidation products, by surface network observations of nitrate wet deposition fluxes, and by OMI satellite observations of tropospheric NO2 columns. Upper tropospheric NO2 from lightning makes a large contribution to the satellite observations that must be accounted for when using these data to estimate surface NOx emissions. Aircraft observations of upper tropospheric NO2 are higher than simulated by GEOS-Chem or expected from NO-NO2-O3 photochemical stationary state. NOx levels in the Southeast US are sufficiently low that only half of isoprene oxidation proceeds by the high-NOx pathway to produce ozone; this fraction is only moderately sensitive to changes in NOx emissions because isoprene and NOx emissions are spatially segregated. GEOS-Chem with reduced NOx emissions provides an unbiased simulation of ozone observations from the aircraft and from ozonesondes, and reproduces the observed ozone production efficiency in the boundary layer as derived from a regression of ozone and NOx oxidation products. However, the model is still biased high by 8 ± 13 ppb relative to observed surface ozone in the Southeast US. Ozonesondes launched during midday hours show a 7 ppb ozone decrease from 1.5 km to 0.2 km altitude, whereas GEOS-Chem has no such gradient because of efficient boundary layer mixing. We conclude that model biases in simulating surface ozone over the Southeast US may be due to a combination of excessive NOx emissions and excessive boundary layer vertical mixing.

scholarly journals The influence of European pollution on ozone in the Near East and northern Africa

2008 ◽  
Vol 8 (1) ◽  
pp. 1913-1950 ◽  
Author(s):  
B. N. Duncan ◽  
J. J. West ◽  
Y. Yoshida ◽  
A. M. Fiore ◽  
J. R. Ziemke
Keyword(s):  
Boundary Layer ◽  
Air Quality ◽  
Near East ◽  
Surface Ozone ◽  
Northern Africa ◽  
Ozone Production ◽  
Ozone Pollution ◽  
East European ◽  
European Health ◽  
Ozone Precursor

Abstract. We present a modeling study of the long-range transport of pollution from Europe, showing that European emissions regularly elevate surface ozone by as much as 20 ppbv in summer in northern Africa and the Near East. European emissions cause 50–150 additional violations per year (i.e., above those that would occur without European pollution) of the European health standard for ozone (8-h average >120 μg/m3 or ~60 ppbv) in northern Africa and the Near East. We estimate that 19 000 additional mortalities occur annually in these regions from exposure to European ozone pollution and 50 000 additional deaths globally; the majority of the additional deaths occurs outside of Europe. Much of the pollution from Europe is exported southward at low altitudes in summer to the Mediterranean Sea, northern Africa and the Near East, regions with favorable photochemical environments for ozone production. Our results suggest that assessments of the human health benefits of reducing ozone precursor emissions in Europe should include effects outside of Europe, and that comprehensive planning to improve air quality in northern Africa and the Near East likely needs to address European emissions. We also show that the tropospheric ozone column data product derived from the OMI and MLS instruments is currently of limited value for air quality applications as the portion of the column above the boundary layer and below the tropopause is large and variable, effectively obscuring the boundary layer signal.

scholarly journals Polar boundary layer bromine explosion and ozone depletion events in the chemistry-climate model EMAC v2.52: Implementation and evaluation of AirSnow algorithm

2017 ◽  
Author(s):  
Stefanie Falk ◽  
Björn-Martin Sinnhuber
Keyword(s):  
Boundary Layer ◽  
Sea Ice ◽  
Atmospheric Chemistry ◽  
Dry Deposition ◽  
Ozone Depletion ◽  
Climate Model ◽  
Surface Ozone ◽  
The Arctic ◽  
Vertical Column ◽  
Model Studies

Abstract. Ozone depletion events (ODE) in the polar boundary layer have been observed frequently during spring-time. Most likely, they are related to events of boundary layer enhancement of bromine. Consequently, increased vertical column densities (VCD) of BrO have been observed from satellites. These so called bromine explosion events have been discussed serving as source of tropospheric BrO at high latitudes. We have implemented a treatment of bromine release and recycling on sea ice and snow covered surfaces in the global chemistry-climate model EMAC (ECHAM/MESSy Atmospheric Chemistry) based on the scheme of Toyota et al. (2011). In this scheme, dry deposition fluxes of HBr, HOBr, and BrNO3 over ice and snow covered surfaces are recycled into Br2 fluxes. In addition, dry deposition of O3, dependent on temperature and sunlight, triggers a Br2 release from surfaces associated with first-year sea ice. Many aspects of observed bromine enhancements and associated episodes of near-complete depletion of boundary layer ozone, both in the Arctic and in the Antarctic, are reproduced by this relatively simple approach. We present first results from our global model studies extending over a full annual cycle, including comparisons with GOME satellite BrO VCD and surface ozone observations.

Transport and boundary layer interaction contribution to extremely high surface ozone levels in eastern China

2021 ◽  
Vol 268 ◽  
pp. 115804
Author(s):  
Xiao-Bing Li ◽  
Guangqiang Fan ◽  
Shengrong Lou ◽  
Bin Yuan ◽  
Xuemei Wang ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Surface Ozone ◽  
Eastern China ◽  
High Surface ◽  
Layer Interaction ◽  
Boundary Layer Interaction ◽  
Interaction Contribution ◽  
Ozone Levels

Using 1D-modelling to study Arctic chlorine activation, transport and VOC oxidation during Arctic springtime

2021 ◽  
Author(s):  
Shaddy Ahmed ◽  
Jennie Thomas ◽  
Katie Tuite ◽  
Jochen Stutz ◽  
Frank Flocke ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Atmospheric Chemistry ◽  
Transport Model ◽  
Numerical Models ◽  
Surface Ozone ◽  
Vertical Mixing ◽  
Mixing Ratios ◽  
Oxidation Rates ◽  
Halogen Chemistry

&lt;p&gt;Polar halogen chemistry has long been known to be active, especially in spring, and is known to have an important influence on the lifetime of some volatile organics, ozone and mercury. Our understanding of polar halogen chemistry is changing, including the recognition that there is active chlorine, bromine and iodine chemistry occurring within the polar boundary. Recently, very high concentrations of molecular chlorine (Cl&lt;sub&gt;2&lt;/sub&gt;) were recorded at Utqia&amp;#289;vik, Alaska during the Ocean-Atmosphere-Sea Ice-Snowpack (OASIS) campaign in spring 2009, with a correlation between daytime Cl&lt;sub&gt;2&lt;/sub&gt; mixing ratios, ozone concentrations and sunlight. However, the chlorine radical concentrations inferred from these Cl&lt;sub&gt;2&lt;/sub&gt; measurements, with the observed VOC abundances and lifetimes, cannot yet be fully explained via chemical box modelling alone. To explain these discrepancies, modelling that includes surface snow Cl&lt;sub&gt;2&lt;/sub&gt; formation processes, subsequent atmospheric chemistry and vertical mixing is needed and is an essential tool in quantifying impacts on VOC lifetimes and the role of vertical mixing in controlling boundary layer chemistry.&lt;/p&gt;&lt;p&gt;In this work, we use a one-dimensional atmospheric chemistry and transport model (Platform for Atmospheric Chemistry and Transport in 1-Dimension, PACT-1D) to investigate surface Cl&lt;sub&gt;2&lt;/sub&gt; production from snow, snowpack recycling, vertical transport and reactivity with VOCs at Utqia&amp;#289;vik, Alaska during the OASIS campaign. We implement a new surface parameterization of chlorine emissions from the snowpack based on the solar irradiance and surface ozone levels and consider the role of vertical mixing processes. By considering both production and transport mechanisms, we are able to obtain good agreement between the model predicted Cl&lt;sub&gt;2&lt;/sub&gt; mixing ratios and observations at 1.5 meters. The model predicts that nearly all reactive chlorine resides within the lowest 15 m of the boundary layer, resulting in increased chemical reactivities and oxidation rates in the lowest part of the atmosphere. VOC abundances near the surface that are co-located with elevated chlorine can be explained by downward mixing of VOCs from aloft, which replenishes VOCs from free tropospheric reservoirs. The proposed surface emission parameterization of chlorine in this work could be used to develop current 3D numerical models in order to explore chlorine emissions and reactivity over the entire Arctic as well as the effects of future Arctic climate scenarios on atmospheric halogen chemistry.&lt;/p&gt;

scholarly journals Comment on “Simulation of Surface Ozone Pollution in the Central Gulf Coast Region Using WRF/Chem Model: Sensitivity to PBL and Land Surface Physics”

2011 ◽  
Vol 2011 ◽  
pp. 1-3 ◽  
Author(s):  
Jonathan E. Pleim
Keyword(s):  
Boundary Layer ◽  
Air Quality ◽  
Land Surface ◽  
Gulf Coast ◽  
Surface Ozone ◽  
Air Quality Modeling ◽  
Weather Research And Forecasting ◽  
Ozone Pollution ◽  
Quality Modeling ◽  
Gulf Coast Region

A recently published meteorology and air quality modeling study has several serious deficiencies deserving comment. The study uses the weather research and forecasting/chemistry (WRF/Chem) model to compare and evaluate boundary layer and land surface modeling options. The most serious of the study's deficiencies is reporting WRF/Chem results for both meteorological and chemical quantities using the asymmetric convective model version 2 (ACM2). While the ACM2 is a valid model option for WRF, it has not yet been implemented for the chemical portion of the WRF/Chem model. Hence, the reported air quality modeling results using ACM2 are invalid. Furthermore, publication of these results gives the erroneous impression that the ACM2 model is not well suited for air quality applications when, in fact, it is the default boundary layer model in the community multiscale air quality (CMAQ) model.

scholarly journals An evaluation of the ability of the Ozone Monitoring Instrument (OMI) to observe boundary layer ozone pollution across China: application to 2005–2017 ozone trends

2019 ◽  
Vol 19 (9) ◽  
pp. 6551-6560 ◽  
Author(s):  
Lu Shen ◽  
Daniel J. Jacob ◽  
Xiong Liu ◽  
Guanyu Huang ◽  
Ke Li ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Tropospheric Ozone ◽  
Southern China ◽  
Surface Ozone ◽  
Eastern China ◽  
Ozone Pollution ◽  
Ozone Monitoring Instrument ◽  
Monitoring Instrument ◽  
Ozone Monitoring ◽  
Boundary Layer Ozone

Abstract. Nadir-viewing satellite observations of tropospheric ozone in the UV have been shown to have some sensitivity to boundary layer ozone pollution episodes, but so far they have not yet been compared to surface ozone observations collected by large-scale monitoring networks. Here we use 2013–2017 surface ozone data from China's new Ministry of Ecology and Environment (MEE) network of ∼ 1000 sites, together with vertical profiles from ozonesondes and aircraft, to quantify the ability of tropospheric ozone retrievals from the Ozone Monitoring Instrument (OMI) and to detect boundary layer ozone pollution in China. We focus on summer when ozone pollution in China is most severe and when OMI has the strongest sensitivity. After subtracting the Pacific background, we find that the 2013–2017 mean OMI ozone enhancements over eastern China have strong spatial correlation with the corresponding multiyear means in the surface afternoon observations (R=0.73), and that OMI can estimate these multiyear means in summer afternoon surface ozone with a precision of 8 ppb. The OMI data show significantly higher values on observed surface ozone episode days (>82 ppb) than on non-episode days. Day-to-day correlations with surface ozone are much weaker due to OMI noise and are stronger for sites in southern China (<34∘ N; R=0.3–0.6) than in northern China (R=0.1–0.3) because of weaker retrieval sensitivity and larger upper tropospheric variability in the north. Ozonesonde data show that much of the variability of OMI ozone over southern China in summer is driven by the boundary layer. Comparison of 2005–2009 and 2013–2017 OMI data indicates that mean summer afternoon surface ozone in southern China (including urban and rural regions) has increased by 3.5±3.0 ppb over the 8-year period and that the number of episode days per summer has increased by 2.2±0.4 (as diagnosed by an extreme value model), generally consistent with the few long-term surface records. Ozone increases have been particularly large in the Yangtze River Delta and in the Hubei, Guangxi and Hainan provinces.

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