scholarly journals Average versus high surface ozone levels over the continental U.S.A.: Model bias, background influences, and interannual variability

2018 ◽  
Author(s):  
Jean J. Guo ◽  
Arlene M. Fiore ◽  
Lee T. Murray ◽  
Daniel A. Jaffe ◽  
Jordan L. Schnell ◽  
...  
Keyword(s):  
Interannual Variability ◽  
Transport Model ◽  
Surface Ozone ◽  
High Surface ◽  
Anthropogenic Sources ◽  
Pollution Transport ◽  
Natural Sources ◽  
Model Biases ◽  
Regional Sources ◽  
Surface O3

Abstract. U.S. background ozone (O3) includes O3 produced from anthropogenic O3 precursors emitted outside of the U.S.A., from global methane, and from any natural sources. Using a suite of sensitivity simulations in the GEOS-Chem global chemistry-transport model, we estimate the influence from individual background versus U.S. anthropogenic sources on total surface O3 over ten continental U.S. regions from 2004–2012. Evaluation with observations reveals model biases of +0–19 ppb in seasonal mean maximum daily 8-hour average (MDA8) O3, highest in summer over the eastern U.S.A. Simulated high-O3 events cluster too late in the season. We link these model biases to regional O3 production (e.g., U.S. anthropogenic, biogenic volatile organic compounds (BVOC), and soil NOx, emissions), or coincident missing sinks. On the ten highest observed O3 days during summer (O3_top10obs_JJA), U.S. anthropogenic emissions enhance O3 by 5–11 ppb and by less than 2 ppb in the eastern versus western U.S.A. The O3 enhancement from BVOC emissions during summer is 1–7 ppb higher on O3_top10obs_JJA days than on average days, while intercontinental pollution is up to 2 ppb higher on average vs. on O3_top10obs_JJA days. In the model, regional sources of O3 precursor emissions drive interannual variability in the highest observed O3 levels. During the summers of 2004–2012, monthly regional mean U.S. background O3 MDA8 levels vary by 10–20 ppb. Simulated summertime total surface O3 levels on O3_top10obs_JJA days decline by 3 ppb (averaged over all regions) from 2004–2006 to 2010–2012 in both the observations and the model, reflecting rising U.S. background (+2 ppb) and declining U.S. anthropogenic O3 emissions (−6 ppb). The model attributes interannual variability in U.S. background O3 on O3_top10obs days to natural sources, not international pollution transport. We find that a three-year averaging period is not long enough to eliminate interannual variability in background O3.

scholarly journals Average versus high surface ozone levels over the continental USA: model bias, background influences, and interannual variability

2018 ◽  
Vol 18 (16) ◽  
pp. 12123-12140 ◽  
Author(s):  
Jean J. Guo ◽  
Arlene M. Fiore ◽  
Lee T. Murray ◽  
Daniel A. Jaffe ◽  
Jordan L. Schnell ◽  
...  
Keyword(s):  
Interannual Variability ◽  
Transport Model ◽  
Surface Ozone ◽  
High Surface ◽  
Anthropogenic Sources ◽  
Pollution Transport ◽  
Natural Sources ◽  
Model Biases ◽  
The Usa ◽  
Surface O3

Abstract. US background ozone (O3) includes O3 produced from anthropogenic O3 precursors emitted outside of the USA, from global methane, and from any natural sources. Using a suite of sensitivity simulations in the GEOS-Chem global chemistry transport model, we estimate the influence from individual background sources versus US anthropogenic sources on total surface O3 over 10 continental US regions from 2004 to 2012. Evaluation with observations reveals model biases of +0–19 ppb in seasonal mean maximum daily 8 h average (MDA8) O3, highest in summer over the eastern USA. Simulated high-O3 events cluster too late in the season. We link these model biases to excessive regional O3 production (e.g., US anthropogenic, biogenic volatile organic compounds (BVOCs), and soil NOx, emissions), or coincident missing sinks. On the 10 highest observed O3 days during summer (O3_top10obs_JJA), US anthropogenic emissions enhance O3 by 5–11 ppb and by less than 2 ppb in the eastern versus western USA. The O3 enhancement from BVOC emissions during summer is 1–7 ppb higher on O3_top10obs_JJA days than on average days, while intercontinental pollution is up to 2 ppb higher on average versus on O3_top10obs_JJA days. During the summers of 2004–2012, monthly regional mean US background O3 MDA8 levels vary by up to 15 ppb from year to year. Observed and simulated summertime total surface O3 levels on O3_top10obs_JJA days decline by 3 ppb (averaged over all regions) from 2004–2006 to 2010–2012, reflecting rising US background (+2 ppb) and declining US anthropogenic O3 emissions (−6 ppb) in the model. The model attributes interannual variability in US background O3 on O3_top10obs days to natural sources, not international pollution transport. We find that a 3-year averaging period is not long enough to eliminate interannual variability in background O3 on the highest observed O3 days.

scholarly journals The relative importance of various source regions on East Asian surface ozone

2010 ◽  
Vol 10 (4) ◽  
pp. 9077-9120 ◽  
Author(s):  
T. Nagashima ◽  
T. Ohara ◽  
K. Sudo ◽  
H. Akimoto
Keyword(s):  
East Asia ◽  
Korean Peninsula ◽  
Transport Model ◽  
Surface Ozone ◽  
East Asian ◽  
Large Contribution ◽  
Chemical Transport Model ◽  
Substantial Impact ◽  
Source Regions ◽  
Surface O3

Abstract. The Source-Receptor (S-R) relationship for surface O3 in East Asia is estimated for recent years in this study utilizing the tagged tracer method with a global chemical transport model. The estimation shows the importance of intra-continental transport of O3 inside East Asia as well as the transport of O3 from distant source regions. The model well simulated the absolute concentration and seasonal variation of surface O3 in the East Asian region, and demonstrated significant seasonal difference in the origin of surface O3. More than half of surface O3 is attributable to the O3 transported from distant sources outside of East Asia in the cold season (October to March). In the warm season (April to September), most of the surface O3 is attributed to O3 created within East Asia in most areas of East Asia. The contribution of domestically-created O3 accounts for 20% of surface O3 in Japan and the Korean Peninsula, 40% in North China Plain and around 50% in the southern part of China in spring, which increase greatly in summer. The contribution of China and the Korean Peninsula to Japan are estimated at about 10% and 5%, respectively. A large contribution (20%) of China to the Korean Peninsula is also demonstrated. In the northern and southern part of China, large contribution of over 10% from East Siberia and the Indochina Peninsula are identified, respectively. The contribution of intercontinental transport increases with latitude; it is 21% in Northeast China and 13% in Japan and the Korean Peninsula in spring. As for one-hourly mean surface O3, domestically-created O3 is the main contributor in most areas of East Asia, except for the low O3 class (<30 ppbv), and accounts for more than 50% in very high O3 class (>90 ppbv). The mean relative contribution of China to central Japan was about 10% in every class, but that from the Korean Peninsula is important in all expect the low O3 class. Substantial impact of foreign sources on the exceedance of Japan's AAQS is identified in the high O3 class (60–90 ppbv) in spring.

scholarly journals Modelling surface ozone during the 2003 heat wave in the UK

2009 ◽  
Vol 9 (5) ◽  
pp. 19509-19544 ◽  
Author(s):  
M. Vieno ◽  
A. J. Dore ◽  
D. S. Stevenson ◽  
R. Doherty ◽  
M. R. Heal ◽  
...  
Keyword(s):  
Heat Wave ◽  
Transport Model ◽  
Temporal Structure ◽  
Surface Ozone ◽  
Wrf Model ◽  
Ground Level ◽  
Reanalysis Data ◽  
Diurnal Cycles ◽  
The Uk ◽  
Surface O3

Abstract. A high resolution (5×5 km2) UK-scale chemistry-transport model (EMEP4UK) is used to study ground-level ozone (O3) during the August 2003 heat-wave. Meteorology is generated by the Weather Research and Forecast (WRF) model, nudged every six hours with reanalysis data. We focus on SE England, where hourly average O3 reached up to 140 ppb during the heat-wave. EMEP4UK accurately reproduces observed annual and diurnal cycles of surface O3 at urban and rural sites. Elevated O3 and much of its day-to-day variability during the heat-wave are well captured. Key O3 precursors, nitrogen dioxide and isoprene (C5H8), are less well simulated, but show generally accurate diurnal cycles and concentrations to within a factor of ~2–3 of observations. The modelled surface O3 distribution has an intricate spatio-temporal structure, governed by a combination of meteorology, emissions and photochemistry. A series of sensitivity runs with the model are used to explore the factors that influenced O3 levels during the heat-wave. Various factors appear to be important on different days and at different sites. Ozone imported from outside the model domain, especially the south, is very important on several days during the heat-wave, contributing up to 85 ppb. Dry deposition of O3, when completely switched off, elevated simulated O3 by up to 50 ppb, and this may have been an important factor on several days. Modelled C5H8 concentrations are generally best simulated if C5H8 emissions are changed from the base emissions: typically doubled, but elevated by up to a factor of five on some days. Accurately modelling the exact positions of individual plumes of anthropogenically emitted nitrogen oxides and volatile organic compounds is crucial for the successful simulation of O3 at a particular time and location. Variations in surface temperature of ±5 K were found to have impacts on O3 of typically less than ±10 ppb.

scholarly journals Reanalysis of and attribution to near-surface ozone concentrations in Sweden during 1990–2013

2017 ◽  
Author(s):  
Camilla Andersson ◽  
Heléne Alpfjord ◽  
Lennart Robertson ◽  
Per Erik Karlsson ◽  
Magnuz Engardt
Keyword(s):  
Transport Model ◽  
Linear Trend ◽  
Surface Ozone ◽  
Vegetation Indices ◽  
High Sensitivity ◽  
Anthropogenic Emissions ◽  
Data Sets ◽  
Chemistry Transport Model ◽  
Near Surface ◽  
Surface O3

Abstract. We have constructed two data sets of hourly resolution reanalyzed near-surface ozone (O3) concentrations for the period 1990–2013 for Sweden. Long-term simulations from a chemistry-transport model (CTM) covering Europe were combined with hourly ozone concentration observations at Swedish and Norwegian background measurement sites using data assimilation. The reanalysis data sets show improved performance than the original CTM when compared to independent observations. In one of the reanalyzes we included all available hourly near-surface O3 observations, whilst in the other we carefully selected time-consistent observations in order to avoid introducing artificial trends. Based on the second reanalysis we investigated statistical aspects of the near-surface O3 concentration, focusing on the linear trend over the 24 year period. We show that high near-surface O3 concentrations are decreasing and low O3 concentrations are increasing, which is mirrored by observed improvement of many health and vegetation indices (apart from those with a low threshold). Using the chemistry-transport model we also conducted sensitivity simulations to quantify the causes of the observed change, focusing on three processes: change in hemispheric background, meteorology and anthropogenic emissions (Swedish and other European). The rising low concentrations of near-surface O3 in Sweden are caused by a combination of all three processes, whilst the decrease in the highest O3 concentrations is caused by O3 precursor emissions reductions. While studying the relative impact of anthropogenic emissions changes, we identified systematic differences in the modelled trend compared to observations that must be caused by incorrect trends in the utilised emissions inventory or by too high sensitivity of our model to emissions changes.

scholarly journals A global model study of ozone enhancement during the August 2003 heat wave in Europe

2007 ◽  
Vol 4 (5) ◽  
pp. 285 ◽  
Author(s):  
G. Guerova ◽  
N. Jones
Keyword(s):  
Heat Wave ◽  
Prediction Models ◽  
Extreme Event ◽  
Transport Model ◽  
Weather Prediction ◽  
Surface Ozone ◽  
Anthropogenic Emissions ◽  
Model Study ◽  
Reactive Pollutant ◽  
Surface O3

Environmental context. During the 2003 European summer, record high temperatures were measured and some regions experienced 14 consecutive days with maximum temperatures above 35°C, thus triggering a heat wave. The prolonged heat and strong insolation facilitated the build up of exceptionally long-lasting and spatially extensive episodes of high ozone concentrations close to the surface. Ozone is a very reactive pollutant with known effects on both human and vegetation health. It is important to build robust models that can predict its concentration in a similar manner to which weather prediction models operate. Abstract. The European summer of 2003 was characterised by intense heat, prolonged isolation and suppressed ventilation of the boundary layer which, combined with large anthropogenic emissions and strong fires, resulted in a build up of an unprecedentedly high and long-lasting photochemical smog over large parts of the continent. In this work, a global chemistry and transport model GEOS-Chem is compared with surface O3 concentrations observed in 2003 in order to examine the extent to which the model is capable of reproducing such an extreme event. The GEOS-Chem reproduces the temporal variation of O3 at the Jungfraujoch mountain site, Switzerland, including the enhanced concentrations associated with the August 2003 heat wave (r = 0.84). The spatial distribution of the enhanced surface O3 over Spain, France, Germany and Italy is also captured to some extent (r = 0.63), although the largest concentrations appear to be located over the Italian Peninsula in the model rather than over Central Europe as suggested by the surface O3 observations. In general, the observed differences between the European averaged O3 concentrations in the summer of 2003 to those in 2004 are larger in the observations than in the model, as the model reproduces relatively well the enhanced levels in 2003 but overestimates those observed in 2004. Preliminary contributions of various sources to the O3 surface concentrations over Europe during the heat wave indicate that anthropogenic emissions from Europe contribute the most to the O3 build up near the surface (40 to 50%, i.e. 30 ppb). The contribution from anthropogenic emissions from the other major source regions of the northern hemisphere, in particular North America, tends to be smaller than those of other years. The model indicates that the large fires that occurred in that year contributed up to 5% (3 ppb) to surface O3 in close proximity to the fire regions and less elsewhere in Europe. Biogenic volatile organic compounds (VOCs) emitted by grass and forest areas contributed up to 10% (5–6 ppb) of surface O3 over France, Germany and northern Italy, which represents a contribution that is twice as large than that found in 2004. These results in terms of contributions from various sources, particularly biogenic emissions, should be seen as preliminary, as the response of vegetation to such extreme events may not be well represented in the model.

scholarly journals Influences of the variation in inflow to East Asia on surface ozone over Japan during 1996–2005

2011 ◽  
Vol 11 (16) ◽  
pp. 8745-8758 ◽  
Author(s):  
S. Chatani ◽  
K. Sudo
Keyword(s):  
East Asia ◽  
Interannual Variability ◽  
Transport Model ◽  
Surface Ozone ◽  
Chemical Transport ◽  
Chemical Transport Model ◽  
Term Trend ◽  
East Asian Region ◽  
Long Term Trend

Abstract. Air quality simulations in which the global chemical transport model CHASER and the regional chemical transport model WRF/chem are coupled have been developed to consider the dynamic transport of chemical species across the boundaries of the domain of the regional chemical transport model. The simulation captures the overall seasonal variations of surface ozone, but overestimates its concentration over Japanese populated areas by approximately 20 ppb from summer to early winter. It is deduced that ozone formation around Northeast China and Japan in summer is overestimated in the simulation. On the other hand, the simulation well reproduces the interannual variability and the long-term trend of observed surface ozone over Japan. Sensitivity experiments have been performed to investigate the influence of the variation in inflow to East Asia on the interannual variability and the long-term trend of surface ozone over Japan during 1996–2005. The inflow defined in this paper includes the recirculation of species with sources within the East Asian region as well as the transport of species with sources out of the East Asian region. Results of sensitivity experiments suggest that inflow to East Asia accounts for approximately 30 % of the increasing trend of surface ozone, whereas it has much less influence on the interannual variability of observed surface ozone compared to meteorological processes within East Asia.

scholarly journals The relative importance of various source regions on East Asian surface ozone

2010 ◽  
Vol 10 (22) ◽  
pp. 11305-11322 ◽  
Author(s):  
T. Nagashima ◽  
T. Ohara ◽  
K. Sudo ◽  
H. Akimoto
Keyword(s):  
East Asia ◽  
Korean Peninsula ◽  
Transport Model ◽  
Surface Ozone ◽  
Ambient Air ◽  
Large Contribution ◽  
Chemical Production ◽  
Substantial Impact ◽  
Source Regions ◽  
Surface O3

Abstract. We estimated the source-receptor relationship for surface O3 in East Asia during the early 2000s using a method that tags O3 tracers according to their region of chemical production (tagged tracer method) with a global chemical transport model. The estimation demonstrated the importance of intracontinental transport of O3 inside East Asia as well as of the transport of O3 from distant source regions. The model well simulated the absolute concentration and seasonal variation of surface O3 in East Asia and demonstrated significant seasonal differences in the origin of surface O3. In the cold season (October to March), more than half of surface O3 in East Asia is attributable to the O3 transported from distant sources outside of East Asia. In the warm season (April to September), most of the surface O3 is attributable to O3 created within East Asia in most areas of East Asia. In spring the contribution of domestically created O3 accounted for 20% of the surface O3 in Japan and the Korean Peninsula, 40% in the North China Plain, and around 50% in the southern part of China, and the domestic contribution increased greatly in summer. The contributions of O3 created in China and the Korean Peninsula to O3 in Japan were estimated at about 10% and 5%, respectively. We also demonstrated a large contribution (20%) from China to the Korean Peninsula. In the northern and southern parts of China, large contributions of over 10% from East Siberia and the Indochina Peninsula, respectively, were identified. The contribution from intercontinental transport increased with latitude; it was 21% in Northeast China and 13% in Japan and the Korean Peninsula in spring. As for the hourly mean of surface O3, domestically created O3 was the main contributor in most areas of East Asia, except for the low O3 class (<30 ppbv), and accounted for more than 50% in the very high O3 class (>90 ppbv). The mean relative contribution of O3 created in China to O3 in central Japan was about 10% in every class, but that created in the Korean Peninsula was significant in all except the low O3 class. We identified the substantial impact of foreign sources on Japan's ambient air quality standard in the high O3 class (60–90 ppbv) in spring.

scholarly journals Reanalysis of and attribution to near-surface ozone concentrations in Sweden during 1990–2013

2017 ◽  
Vol 17 (22) ◽  
pp. 13869-13890 ◽  
Author(s):  
Camilla Andersson ◽  
Heléne Alpfjord ◽  
Lennart Robertson ◽  
Per Erik Karlsson ◽  
Magnuz Engardt
Keyword(s):  
Transport Model ◽  
Linear Trend ◽  
Surface Ozone ◽  
Vegetation Indices ◽  
High Sensitivity ◽  
Anthropogenic Emissions ◽  
Data Sets ◽  
Near Surface ◽  
The Impact ◽  
Surface O3

Abstract. We have constructed two data sets of hourly resolution reanalyzed near-surface ozone (O3) concentrations for the period 1990–2013 for Sweden. Long-term simulations from a chemistry-transport model (CTM) covering Europe were combined with hourly ozone concentration observations at Swedish and Norwegian background measurement sites using retrospective variational data analysis. The reanalysis data sets show improved performance over the original CTM when compared to independent observations. In one of the reanalyses, we included all available hourly near-surface O3 observations, whilst in the other we carefully selected time-consistent observations. Based on the second reanalysis we investigated statistical aspects of the distribution of the near-surface O3 concentrations, focusing on the linear trend over the 24-year period. We show that high near-surface O3 concentrations are decreasing and low O3 concentrations are increasing, which is reflected in observed improvement of many health and vegetation indices (apart from those with a low threshold). Using the CTM we also conducted sensitivity simulations to quantify the causes of the observed change, focusing on three factors: change in hemispheric background concentrations, meteorology and anthropogenic emissions. The rising low concentrations of near-surface O3 in Sweden are caused by a combination of all three factors, whilst the decrease in the highest O3 concentrations is caused by European O3 precursor emissions reductions. While studying the impact of anthropogenic emissions changes, we identified systematic differences in the modeled trend compared to observations that must be caused by incorrect trends in the utilized emissions inventory or by too high sensitivity of our model to emissions changes.

scholarly journals Attribution of future US ozone pollution to regional emissions, climate change, long-range transport, and model deficiency

2014 ◽  
Vol 14 (19) ◽  
pp. 26231-26256 ◽  
Author(s):  
H. He ◽  
X.-Z. Liang ◽  
H. Lei ◽  
D. J. Wuebbles
Keyword(s):  
Climate Change ◽  
Long Range ◽  
Transport Model ◽  
Surface Ozone ◽  
Long Range Transport ◽  
Ozone Pollution ◽  
Model Biases ◽  
Range Transport ◽  
Regional Emissions ◽  
Model Deficiency

Abstract. A regional chemical transport model (CTM) is used to quantify the relative contributions of future US ozone pollution from regional emissions, climate change, long-range transport (LRT) of pollutants, and model deficiency. After incorporating dynamic lateral boundary conditions (LBCs) from a global CTM, the representation of present-day US ozone pollution is notably improved. This nested system projects substantial surface ozone trends for 2050's: 6–10 ppbv decreases under the "clean" A1B scenario and ~15 ppbv increases under the "dirty" A1Fi scenario. Among the total trends, regional emissions changes dominate, contributing negative 20–50% in A1B and positive 20–40% in A1Fi, while LRT effects through chemical LBCs and climate changes account for respectively 15–50% and 10–30% in both scenarios. The projection uncertainty due to model biases is region dependent, ranging from −10 to 50%. It is shown that model biases of present-day simulations can propagate into future projections systematically but nonlinearly, and the accurate specification of LBCs is essential for US ozone projections.

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