scholarly journals Effects of stratospheric ozone recovery on tropospheric chemistry and air quality

2013 ◽  
Vol 13 (8) ◽  
pp. 21427-21453
Author(s):  
H. Zhang ◽  
S. Wu ◽  
Y. Wang
Keyword(s):  
Air Quality ◽  
Transport Model ◽  
Stratospheric Ozone ◽  
Surface Ozone ◽  
Montreal Protocol ◽  
Tropospheric Chemistry ◽  
Chemical Transport Model ◽  
Photolysis Rates ◽  
Global Chemical Transport Model ◽  
Ozone Depleting Substances

Abstract. The stratospheric ozone has decreased greatly since 1980 due to ozone depleting substances (ODSs). As a result of the implementation of the Montreal Protocol and its amendments and adjustments, stratospheric ozone is expected to recover towards its pre-1980 level in the coming decades. We examine the implications of stratospheric ozone recovery for the tropospheric chemistry and ozone air quality with a global chemical transport model (GEOS-Chem). Significant decreases in surface ozone photolysis rates due to stratospheric ozone recovery are simulated. Increases in ozone lifetime by up to 7% are calculated in the troposphere. The global average OH decreases by 1.74% and the global burden of tropospheric ozone increases by 0.78%. The perturbations to tropospheirc ozone and surface ozone show large seasonal and spatial variations. General increases in surface ozone are calculated for each season, with increases by up to 5% for some regions.

scholarly journals Effects of stratospheric ozone recovery on photochemistry and ozone air quality in the troposphere

2014 ◽  
Vol 14 (8) ◽  
pp. 4079-4086 ◽  
Author(s):  
H. Zhang ◽  
S. Wu ◽  
Y. Huang ◽  
Y. Wang
Keyword(s):  
Air Quality ◽  
Tropospheric Ozone ◽  
Stratospheric Ozone ◽  
Surface Ozone ◽  
Montreal Protocol ◽  
Tropospheric Chemistry ◽  
Sensitivity Factor ◽  
Global Average ◽  
Photolysis Rate ◽  
Ozone Column

Abstract. There has been significant stratospheric ozone depletion since the late 1970s due to ozone-depleting substances (ODSs). With the implementation of the Montreal Protocol and its amendments and adjustments, stratospheric ozone is expected to recover towards its pre-1980 level in the coming decades. In this study, we examine the implications of stratospheric ozone recovery for the tropospheric chemistry and ozone air quality with a global chemical transport model (GEOS-Chem). With a full recovery of the stratospheric ozone, the projected increases in ozone column range from 1% over the low latitudes to more than 10% over the polar regions. The sensitivity factor of troposphere ozone photolysis rate, defined as the percentage changes in surface ozone photolysis rate for 1% increase in stratospheric ozone column, shows significant seasonal variation but is always negative with absolute value larger than one. The expected stratospheric ozone recovery is found to affect the tropospheric ozone destruction rates much more than the ozone production rates. Significant decreases in surface ozone photolysis rates due to stratospheric ozone recovery are simulated. The global average tropospheric OH decreases by 1.7%, and the global average lifetime of tropospheric ozone increases by 1.5%. The perturbations to tropospheric ozone and surface ozone show large seasonal and spatial variations. General increases in surface ozone are calculated for each season, with increases by up to 0.8 ppbv in the remote areas. Increases in ozone lifetime by up to 13% are found in the troposphere. The increased lifetimes of tropospheric ozone in response to stratospheric ozone recovery enhance the intercontinental transport of ozone and global pollution, in particular for the summertime. The global background ozone attributable to Asian emissions is calculated to increase by up to 15% or 0.3 ppbv in the Northern Hemisphere in response to the projected stratospheric ozone recovery.

scholarly journals The added value of a visible channel to a geostationary thermal infrared instrument to monitor ozone for air quality

2014 ◽  
Vol 7 (2) ◽  
pp. 1645-1689
Author(s):  
E. Hache ◽  
J.-L. Attié ◽  
C. Tourneur ◽  
P. Ricaud ◽  
L. Coret ◽  
...  
Keyword(s):  
Air Quality ◽  
Transport Model ◽  
Statistical Tests ◽  
Surface Ozone ◽  
A Priori ◽  
Thermal Infrared ◽  
Added Value ◽  
Chemical Transport Model ◽  
Geo Satellite ◽  
Sky Conditions

Abstract. Ozone is a tropospheric pollutant and plays a key role in determining the air quality that affects human wellbeing. In this study, we compare the capability of two hypothetical grating spectrometers onboard a geostationary (GEO) satellite to sense ozone in the lowermost troposphere (surface and the 0–1 km column). We consider one week during the Northern Hemisphere summer simulated by a chemical transport model, and use the two GEO instrument configurations to measure ozone concentration (1) in the thermal infrared (GEO TIR) and (2) in the thermal infrared and the visible (GEO TIR+VIS). These configurations are compared against each other, and also against an ozone reference state and a priori ozone information. In a first approximation, we assume clear sky conditions neglecting the influence of aerosols and clouds. A number of statistical tests are used to assess the performance of the two GEO configurations. We consider land and sea pixels and whether differences between the two in the performance are significant. Results show that the GEO TIR+VIS configuration provides a better representation of the ozone field both for surface ozone and the 0–1 km ozone column during the daytime especially over land.

scholarly journals Coupling between surface ozone and leaf area index in a chemical transport model: strength of feedback and implications for ozone air quality and vegetation health

2018 ◽  
Vol 18 (19) ◽  
pp. 14133-14148 ◽  
Author(s):  
Shan S. Zhou ◽  
Amos P. K. Tai ◽  
Shihan Sun ◽  
Mehliyar Sadiq ◽  
Colette L. Heald ◽  
...  
Keyword(s):  
Air Quality ◽  
Leaf Area Index ◽  
Leaf Area ◽  
Dry Deposition ◽  
Transport Model ◽  
Surface Ozone ◽  
Chemical Transport ◽  
Chemical Transport Model ◽  
Area Index ◽  
Ozone Levels

Abstract. Tropospheric ozone is an air pollutant that substantially harms vegetation and is also strongly dependent on various vegetation-mediated processes. The interdependence between ozone and vegetation may constitute feedback mechanisms that can alter ozone concentration itself but have not been considered in most studies to date. In this study we examine the importance of dynamic coupling between surface ozone and leaf area index (LAI) in shaping ozone air quality and vegetation. We first implement an empirical scheme for ozone damage on vegetation in the Community Land Model (CLM) and simulate the steady-state responses of LAI to long-term exposure to a range of prescribed ozone levels (from 0 to 100 ppb). We find that most plant functional types suffer a substantial decline in LAI as ozone level increases. Based on the CLM-simulated results, we develop and implement in the GEOS-Chem chemical transport model a parameterization that computes fractional changes in monthly LAI as a function of local mean ozone levels. By forcing LAI to respond to ozone concentrations on a monthly timescale, the model simulates ozone–LAI coupling dynamically via biogeochemical processes including biogenic volatile organic compound (VOC) emissions and dry deposition, without the complication from meteorological changes. We find that ozone-induced damage on LAI can lead to changes in ozone concentrations by −1.8 to +3 ppb in boreal summer, with a corresponding ozone feedback factor of −0.1 to +0.6 that represents an overall self-amplifying effect from ozone–LAI coupling. Substantially higher simulated ozone due to strong positive feedbacks is found in most tropical forests, mainly due to the ozone-induced reductions in LAI and dry deposition velocity, whereas reduced isoprene emission plays a lesser role in these low-NOx environments. In high-NOx regions such as the eastern US, Europe, and China, however, the feedback effect is much weaker and even negative in some regions, reflecting the compensating effects of reduced dry deposition and reduced isoprene emission (which reduces ozone in high-NOx environments). In remote, low-LAI regions, including most of the Southern Hemisphere, the ozone feedback is generally slightly negative due to the reduced transport of NOx–VOC reaction products that serve as NOx reservoirs. This study represents the first step to accounting for dynamic ozone–vegetation coupling in a chemical transport model with ramifications for a more realistic joint assessment of ozone air quality and ecosystem health.

Exploring the trends and potential drivers of surface ozone in eastern China in 2015-2018

2020 ◽  
Author(s):  
Ning Yang ◽  
Yanru Bai ◽  
Yong Zhu ◽  
Nan Ma ◽  
Qiaoqiao Wang
Keyword(s):  
Air Quality ◽  
Transport Model ◽  
Surface Ozone ◽  
Eastern China ◽  
Yangtze River Delta ◽  
River Delta ◽  
Pearl River Delta Region ◽  
Chemical Transport Model ◽  
Delta Region ◽  
Almost All

<p>In the last six years, China has experienced significant improvement in air quality due to great emission reduction efforts. However, ozone concentrations are still slowly increasing in three major regions of eastern China, respectively Jing-Jin-Ji(JJJ), Yangtze River Delta region(YRD) and Pearl River Delta region(PRD). It is shown from the 2015-2018 national urban air quality real-time release platform that the surface ozone in JJJ, YRD and PRD has increased each year and reached the highest in 2018. The monthly ozone concentration peaked in June in almost all cities of JJJ, while it had multiple peaks in other two regions (summer and autumn in YRD - and February, May and September in PRD). Simulation with a chemical transport model(GEOS-Chem) indicates that the formation of ozone is affected by the optical properties of PM<sub>2.5</sub> and also the heterogeneous uptake of N<sub>2</sub>O<sub>5</sub> on sea salt aerosol.</p>

scholarly journals Satellite observations of stratospheric hydrogen fluoride and comparisons with SLIMCAT calculations

2015 ◽  
Vol 15 (23) ◽  
pp. 34361-34405 ◽  
Author(s):  
J. J. Harrison ◽  
M. P. Chipperfield ◽  
C. D. Boone ◽  
S. S. Dhomse ◽  
P. F. Bernath ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Transport Model ◽  
Stratospheric Ozone ◽  
Three Dimensional ◽  
Montreal Protocol ◽  
Chemical Transport Model ◽  
Slowing Down ◽  
Rate Of Increase ◽  
Stratospheric Dynamics ◽  
Chemistry Experiment

Abstract. The vast majority of emissions of fluorine-containing molecules are anthropogenic in nature, e.g. chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and hydrofluorocarbons (HFCs). Many of these fluorine-containing species deplete stratospheric ozone, and are regulated by the Montreal Protocol. Once in the atmosphere they slowly degrade, ultimately leading to the formation of HF, the dominant reservoir of stratospheric fluorine due to its extreme stability. Monitoring the growth of stratospheric HF is therefore an important marker for the success of the Montreal Protocol. We report the comparison of global distributions and trends of HF measured in the Earth's atmosphere by the satellite remote-sensing instruments ACE-FTS (Atmospheric Chemistry Experiment Fourier Transform Spectrometer), which has been recording atmospheric spectra since 2004, and HALOE (HALogen Occultation Experiment), which recorded atmospheric spectra between 1991 and 2005, with the output of SLIMCAT, a state-of-the-art three-dimensional chemical transport model. In general the agreement between observation and model is good, although the ACE-FTS measurements are biased high by ∼ 10 % relative to HALOE. The observed global HF trends reveal a substantial slowing down in the rate of increase of HF since the 1990s: 4.97 ± 0.12 % year-1 (1991–1997; HALOE), 1.12 ± 0.08 % year-1 (1998–2005; HALOE), and 0.52 ± 0.03 % year-1 (2004–2012; ACE-FTS). In comparison, SLIMCAT calculates trends of 4.01, 1.10, and 0.48 % year-1, respectively, for the same periods; the agreement is very good for all but the earlier of the two HALOE periods. Furthermore, the observations reveal variations in the HF trends with latitude and altitude, for example between 2004 and 2012 HF actually decreased in the Southern Hemisphere below ∼ 35 km. SLIMCAT calculations broadly agree with these observations, most notably between 2004 and 2012. Such variations are attributed to variability in stratospheric dynamics over the observation period.

scholarly journals Combined assimilation of IASI and MLS observations to constrain tropospheric and stratospheric ozone in a global chemical transport model

2013 ◽  
Vol 13 (8) ◽  
pp. 21455-21505
Author(s):  
E. Emili ◽  
B. Barret ◽  
S. Massart ◽  
E. Le Flochmoen ◽  
A. Piacentini ◽  
...  
Keyword(s):  
Tropospheric Ozone ◽  
Radiative Forcing ◽  
Transport Model ◽  
Stratospheric Ozone ◽  
Chemical Transport ◽  
Free Troposphere ◽  
Chemical Transport Model ◽  
Ozone Monitoring Instrument ◽  
Global Chemical Transport Model ◽  
The Impact

Abstract. Accurate and temporally resolved fields of free-troposphere ozone are of major importance to quantify the intercontinental transport of pollution and the ozone radiative forcing. In this study we examine the impact of assimilating ozone observations from the Microwave Limb Sounder (MLS) and the Infrared Atmospheric Sounding Interferometer (IASI) in a global chemical transport model (MOdèle de Chimie Atmosphérique à Grande Échelle, MOCAGE). The assimilation of the two instruments is performed by means of a variational algorithm (4-D-VAR) and allows to constrain stratospheric and tropospheric ozone simultaneously. The analysis is first computed for the months of August and November 2008 and validated against ozone-sondes measurements to verify the presence of observations and model biases. It is found that the IASI Tropospheric Ozone Column (TOC, 1000–225 hPa) should be bias-corrected prior to assimilation and MLS lowermost level (215 hPa) excluded from the analysis. Furthermore, a longer analysis of 6 months (July–August 2008) showed that the combined assimilation of MLS and IASI is able to globally reduce the uncertainty (Root Mean Square Error, RMSE) of the modeled ozone columns from 30% to 15% in the Upper-Troposphere/Lower-Stratosphere (UTLS, 70–225 hPa) and from 25% to 20% in the free troposphere. The positive effect of assimilating IASI tropospheric observations is very significant at low latitudes (30° S–30° N), whereas it is not demonstrated at higher latitudes. Results are confirmed by a comparison with additional ozone datasets like the Measurements of OZone and wAter vapour by aIrbus in-service airCraft (MOZAIC) data, the Ozone Monitoring Instrument (OMI) total ozone columns and several high-altitude surface measurements. Finally, the analysis is found to be little sensitive to the assimilation parameters and the model chemical scheme, due to the high frequency of satellite observations compared to the average life-time of free-troposphere/low-stratosphere ozone.

scholarly journals Impact of 2050 climate change on North American wildfire: consequences for ozone air quality

2015 ◽  
Vol 15 (17) ◽  
pp. 10033-10055 ◽  
Author(s):  
X. Yue ◽  
L. J. Mickley ◽  
J. A. Logan ◽  
R. C. Hudman ◽  
M. V. Martin ◽  
...  
Keyword(s):  
Air Quality ◽  
Climate Models ◽  
Transport Model ◽  
Surface Ozone ◽  
Chemical Transport Model ◽  
Activity Increase ◽  
Area Burned ◽  
Air Temperatures ◽  
Projected Changes ◽  
Almost All

Abstract. We estimate future area burned in the Alaskan and Canadian forest by the mid-century (2046–2065) based on the simulated meteorology from 13 climate models under the A1B scenario. We develop ecoregion-dependent regressions using observed relationships between annual total area burned and a suite of meteorological variables and fire weather indices, and apply these regressions to the simulated meteorology. We find that for Alaska and western Canada, almost all models predict significant (p < 0.05) increases in area burned at the mid-century, with median values ranging from 150 to 390 %, depending on the ecoregion. Such changes are attributed to the higher surface air temperatures and 500 hPa geopotential heights relative to present day, which together lead to favorable conditions for wildfire spread. Elsewhere the model predictions are not as robust. For the central and southern Canadian ecoregions, the models predict increases in area burned of 45–90 %. Except for the Taiga Plain, where area burned decreases by 50 %, no robust trends are found in northern Canada, due to the competing effects of hotter weather and wetter conditions there. Using the GEOS-Chem chemical transport model, we find that changes in wildfire emissions alone increase mean summertime surface ozone levels by 5 ppbv for Alaska, 3 ppbv for Canada, and 1 ppbv for the western US by the mid-century. In the northwestern US states, local wildfire emissions at the mid-century enhance surface ozone by an average of 1 ppbv, while transport of boreal fire pollution further degrades ozone air quality by an additional 0.5 ppbv. The projected changes in wildfire activity increase daily summertime surface ozone above the 95th percentile by 1 ppbv in the northwestern US, 5 ppbv in the high latitudes of Canada, and 15 ppbv in Alaska, suggesting a greater frequency of pollution episodes in the future atmosphere.

scholarly journals Linkages between ozone-depleting substances, tropospheric oxidation and aerosols

2013 ◽  
Vol 13 (9) ◽  
pp. 4907-4916 ◽  
Author(s):  
A. Voulgarakis ◽  
D. T. Shindell ◽  
G. Faluvegi
Keyword(s):  
Radiative Forcing ◽  
Scale Effects ◽  
Stratospheric Ozone ◽  
Montreal Protocol ◽  
Tropospheric Chemistry ◽  
Atmospheric Composition ◽  
N2o Emissions ◽  
Sulfate Aerosols ◽  
Comparable Amount ◽  
Ozone Depleting Substances

Abstract. Coupling between the stratosphere and the troposphere allows changes in stratospheric ozone abundances to affect tropospheric chemistry. Large-scale effects from such changes on chemically produced tropospheric aerosols have not been systematically examined in past studies. We use a composition-climate model to investigate potential past and future impacts of changes in stratospheric ozone depleting substances (ODS) on tropospheric oxidants and sulfate aerosols. In most experiments, we find significant responses in tropospheric photolysis and oxidants, with small but significant effects on methane radiative forcing. The response of sulfate aerosols is sizeable when examining the effect of increasing future nitrous oxide (N2O) emissions. We also find that without the regulation of chlorofluorocarbons (CFCs) through the Montreal Protocol, sulfate aerosols could have increased by 2050 by a comparable amount to the decreases predicted due to relatively stringent sulfur emissions controls. The individual historical radiative forcings of CFCs and N2O through their indirect effects on methane (−22.6 mW m−2 for CFCs and −6.7 mW m−2 for N2O) and sulfate aerosols (−3.0 mW m−2 for CFCs and +6.5 mW m−2 for N2O when considering the direct aerosol effect) discussed here are non-negligible when compared to known historical ODS forcing. Our results stress the importance of accounting for stratosphere-troposphere, gas-aerosol and composition-climate interactions when investigating the effects of changing emissions on atmospheric composition and climate.

scholarly journals Air quality and radiative forcing impacts of anthropogenic volatile organic compound emissions from ten world regions

2013 ◽  
Vol 13 (8) ◽  
pp. 21125-21157 ◽  
Author(s):  
M. M. Fry ◽  
M. D. Schwarzkopf ◽  
Z. Adelman ◽  
J. J. West
Keyword(s):  
Air Quality ◽  
Tropospheric Ozone ◽  
Radiative Forcing ◽  
Transport Model ◽  
Surface Ozone ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Chemical Transport Model ◽  
Large Variability ◽  
Volatile Organic

Abstract. Non-methane volatile organic compounds (NMVOCs) influence air quality and global climate change through their effects on secondary air pollutants and climate forcers. Here we simulate the air quality and radiative forcing (RF) impacts of changes in ozone, methane, and sulfate from halving anthropogenic NMVOC emissions globally and from 10 regions individually, using a global chemical transport model and a standalone radiative transfer model. Halving global NMVOC emissions decreases global annual average tropospheric methane and ozone by 36.6 ppbv and 3.3 Tg, respectively, and surface ozone by 0.67 ppbv. All regional reductions slow the production of PAN, resulting in regional to intercontinental PAN decreases and regional NOx increases. These NOx increases drive tropospheric ozone increases nearby or downwind of source regions in the Southern Hemisphere (South America, Southeast Asia, Africa, and Australia). Some regions' NMVOC emissions contribute importantly to air pollution in other regions, such as East Asia, Middle East, and Europe, whose impact on US surface ozone is 43%, 34%, and 34% of North America's impact. Global and regional NMVOC reductions produce widespread negative net RFs (cooling) across both hemispheres from tropospheric ozone and methane decreases, and regional warming and cooling from changes in tropospheric ozone and sulfate (via several oxidation pathways). The total global net RF for NMVOCs is estimated as 0.0277 W m−2 (~1.8% of CO2 RF since the preindustrial). The 100 yr and 20 yr global warming potentials (GWP100, GWP20) are 2.36 and 5.83 for the global reduction, and 0.079 to 6.05 and −1.13 to 18.9 among the 10 regions. The NMVOC RF and GWP estimates are generally lower than previously modeled estimates, due to differences among models in ozone, methane, and sulfate sensitivities, and the climate forcings included in each estimate. Accounting for a~fuller set of RF contributions may change the relative magnitude of each region's impacts. The large variability in the RF and GWP of NMVOCs among regions suggest that regionally-specific metrics may be necessary to include NMVOCs in multi-gas climate trading schemes.

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