Influences of the boundary layer evolution on surface ozone variations at a tropical rural site in India

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.

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Surface ozone variations at a rural area in the northeast of the Iberian Peninsula

Atmospheric Pollution Research ◽

10.5094/apr.2013.013 ◽

2013 ◽

Vol 4 (2) ◽

pp. 130-141 ◽

Cited By ~ 10

Author(s):

Jose A. Adame ◽

Jose G. Sole

Keyword(s):

Iberian Peninsula ◽

Rural Area ◽

Surface Ozone ◽

Ozone Variations

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Entrainment and Mixing of Transported Ozone Layers: Implications for Surface Air Quality in the Western U.S.

EPJ Web of Conferences ◽

10.1051/epjconf/202023703012 ◽

2020 ◽

Vol 237 ◽

pp. 03012

Author(s):

Christoph Senff ◽

Andrew Langford ◽

Raul Alvarez ◽

Tim Bonin ◽

Alan Brewer ◽

...

Keyword(s):

Boundary Layer ◽

Air Quality ◽

Mixed Layer ◽

Las Vegas ◽

Surface Ozone ◽

Ground Level ◽

San Joaquin Valley ◽

Fire Emissions ◽

Ozone Transport ◽

The Impact

Recently, two air quality campaigns were conducted in the southwestern United States to study the impact of transported ozone, stratospheric intrusions, and fire emissions on ground-level ozone concentrations. The California Baseline Ozone Transport Study (CABOTS) took place in May – August 2016 covering the central California coast and San Joaquin Valley, and the Fires, Asian, and Stratospheric Transport Las Vegas Ozone Study (FAST-LVOS) was conducted in the greater Las Vegas, Nevada area in May – June 2017. During these studies, nearly 1000 hours of ozone and aerosol profile data were collected with the NOAA TOPAZ lidar. A Doppler wind lidar and a radar wind profiler provided continuous observations of atmospheric turbulence, horizontal winds, and mixed layer height. These measurements allowed us to directly observe the degree to which ozone transport layers aloft were entrained into the boundary layer and to quantify the resulting impact on surface ozone levels. Mixed layer heights in the San Joaquin Valley during CABOTS were generally below 1 km above ground level (AGL), while boundary layer heights in Las Vegas during FAST-LVOS routinely exceeded 3 km AGL and occasionally reached up to 4.5 km AGL. Consequently, boundary layer entrainment was more often observed during FAST-LVOS, while most elevated ozone layers passed untapped over the San Joaquin Valley during CABOTS.

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Ozone in the Boundary Layer air over the Arctic Ocean – measurements during the TARA expedition

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-9-8561-2009 ◽

2009 ◽

Vol 9 (2) ◽

pp. 8561-8586

Author(s):

J. W. Bottenheim ◽

S. Netcheva ◽

S. Morin ◽

S. V. Nghiem

Keyword(s):

Boundary Layer ◽

Arctic Ocean ◽

Ozone Depletion ◽

Surface Ozone ◽

The Arctic ◽

Total Absence ◽

Trajectory Calculations ◽

The Arctic Ocean ◽

Ocean Measurements ◽

Siberian Coast

Abstract. A full year of measurements of surface ozone over the Arctic Ocean far removed from land is presented (81° N – 88° N latitude). The data were obtained during the drift of the French schooner TARA between September 2006 and January 2008, while frozen in the Arctic Ocean. The data confirm that long periods of virtually total absence of ozone occur in the spring (mid March to mid June) after Polar sunrise. At other times of the year ozone concentrations are comparable to other oceanic observations with winter mole fractions of ca. 30–40 nmol mol−1 and summer minima of ca. 20 nmol mol−1. Contrary to earlier observations from ozone sonde data obtained at Arctic coastal observatories, the ambient temperature was well above −20°C during most ODEs (ozone depletion episodes). Backwards trajectory calculations suggest that during these ODEs the air had previously been in contact with the frozen ocean surface for several days and originated largely from the Siberian coast where several large open flaw leads developed in the spring of 2007.

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The role of open lead interactions in atmospheric ozone variability between Arctic coastal and inland sites

Elem Sci Anth ◽

10.12952/journal.elementa.000109 ◽

2016 ◽

Vol 4 ◽

Cited By ~ 2

Author(s):

Peter K. Peterson ◽

Kerri A. Pratt ◽

William R. Simpson ◽

Son V. Nghiem ◽

Lemuel X. Pérez Pérez ◽

...

Keyword(s):

Boundary Layer ◽

Sea Ice ◽

Ozone Depletion ◽

Surface Ozone ◽

Optical Absorption Spectroscopy ◽

Atmospheric Ozone ◽

Vertical Profiles ◽

Large Spatial Scale ◽

Near Surface ◽

Air Masses

Abstract Boundary layer atmospheric ozone depletion events (ODEs) are commonly observed across polar sea ice regions following polar sunrise. During March-April 2005 in Alaska, the coastal site of Barrow and inland site of Atqasuk experienced ODEs (O3< 10 nmol mol-1) concurrently for 31% of the observations, consistent with large spatial scale ozone depletion. However, 7% of the time ODEs were exclusively observed inland at Atqasuk. This phenomenon also occurred during one of nine flights during the BRomine, Ozone, and Mercury EXperiment (BROMEX), when atmospheric vertical profiles at both sites showed near-surface ozone depletion only at Atqasuk on 28 March 2012. Concurrent in-flight BrO measurements made using nadir scanning differential optical absorption spectroscopy (DOAS) showed the differences in ozone vertical profiles at these two sites could not be attributed to differences in locally occurring halogen chemistry. During both studies, backward air mass trajectories showed that the Barrow air masses observed had interacted with open sea ice leads, causing increased vertical mixing and recovery of ozone at Barrow and not Atqasuk, where the air masses only interacted with tundra and consolidated sea ice. These observations suggest that, while it is typical for coastal and inland sites to have similar ozone conditions, open leads may cause heterogeneity in the chemical composition of the springtime Arctic boundary layer over coastal and inland areas adjacent to sea ice regions.

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Measurements of ozone and its precursors in Beijing during summertime: impact of urban plumes on ozone pollution in downwind rural areas

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-11-17337-2011 ◽

2011 ◽

Vol 11 (6) ◽

pp. 17337-17373 ◽

Cited By ~ 4

Author(s):

J. Xu ◽

J. Z. Ma ◽

X. L. Zhang ◽

X. B. Xu ◽

X. F. Xu ◽

...

Keyword(s):

Rural Areas ◽

Surface Ozone ◽

Regional Scale ◽

Rural Site ◽

Traffic Density ◽

Prevailing Wind ◽

Ozone Pollution ◽

Rural Sites ◽

Urban And Rural Areas ◽

Urban Plumes

Abstract. Sea-land and mount-valley circulations are the dominant mesoscale synoptic systems affecting the Beijing area during summertime. Under the influence of these two circulations, the prevailing wind is southwesterly from afternoon to midnight, and then changes to northeasterly till forenoon. In this study, surface ozone (O3), carbon monoxide (CO), nitric oxide (NO), nitrogen dioxide (NO2), nitrogen oxide (NOx) and non-methane hydrocarbons (NMHCs) were measured at four sites located along the route of prevailing wind, including two upwind urban sites (Fengtai (FT) and Baolian (BL)), an upwind suburban site (Shunyi (SY)) and a downwind rural site (Shangdianzi (SDZ)) during 20 June–16 September 2007. The purpose is to improve our understanding of ozone photochemistry in urban and rural areas of Beijing and the influence of urban plumes on ozone pollution in downwind rural areas. It is found that ozone pollution was synchronism in the urban and rural areas of Beijing, coinciding with the regional-scale synoptic processes. Due to the high traffic density and local emissions, the average levels of reactive gases NOx and NMHCs at the non-rural sites were much higher than those at SDZ. The level of long-lived gas CO at SDZ was comparable to and slightly lower than it was at other sites. The daily-averaged ozone concentration at SDZ was much higher than at other sites due to weak titration. Ranking by OH loss rate coefficient (LOH), alkenes played a dominant role in total NMHCs reactivity at both urban and rural sites during the experiment, accounting for 48.6 % and 52.1 % of total LOH, respectively. The NMHCs data were also used to estimate the ozone potential formation (OFP) in Beijing. The leading contributors to ozone formation were aromatics at both urban and rural sites during the experiment, which accounts for 55.5 % and 49.4 % of total OFP, respectively. The ozone peak values are found to lag behind one site after another along the route of prevailing wind from SW to NE. Intersection analyses of trace gases reveal that polluted air masses arriving at SDZ were more aged with both higher O3 and Ox concentrations than those at BL. The results indicate that urban plume can transport not only O3 but its precursors, the latter leading more photochemical O3 production when being mixed with background atmosphere in the downwind rural area.

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Boundary layer evolution over the central Himalayas from radio wind profiler and model simulations

Atmospheric Chemistry and Physics ◽

10.5194/acp-16-10559-2016 ◽

2016 ◽

Vol 16 (16) ◽

pp. 10559-10572 ◽

Cited By ~ 21

Author(s):

Narendra Singh ◽

Raman Solanki ◽

Narendra Ojha ◽

Ruud H. H. Janssen ◽

Andrea Pozzer ◽

...

Keyword(s):

Boundary Layer ◽

Mixed Layer ◽

Surface Ozone ◽

Wrf Model ◽

Ground Level ◽

Wind Profiler ◽

Pollution Transport ◽

Local Boundary ◽

The Mean

Abstract. We investigate the time evolution of the Local Boundary Layer (LBL) for the first time over a mountain ridge at Nainital (79.5° E, 29.4° N, 1958 m a.m.s.l.) in the central Himalayan region, using a radar wind profiler (RWP) during November 2011 to March 2012, as a part of the Ganges Valley Aerosol Experiment (GVAX). We restrict our analysis to clear–sunny days, resulting in a total of 78 days of observations. The standard criterion of the peak in the signal-to-noise ratio (S ∕ N) profile was found to be inadequate in the characterization of mixed layer (ML) top at this site. Therefore, we implemented a criterion of S ∕ N > 6 dB for the characterization of the ML and the resulting estimations are shown to be in agreement with radiosonde measurements over this site. The daytime average (05:00–10:00 UTC) observed boundary layer height ranges from 440 ± 197 m in November (late autumn) to 766 ± 317 m above ground level (a.g.l.) in March (early spring). The observations revealed a pronounced impact of mountain topography on the LBL dynamics during March, when strong winds (> 5.6 m s−1) lead to LBL heights of 650 m during nighttime. The measurements are further utilized to evaluate simulations from the Weather Research and Forecasting (WRF) model. WRF simulations captured the day-to-day variations up to an extent (r2 = 0.5), as well as the mean diurnal variations (within 1σ variability). The mean biases in the daytime average LBL height vary from −7 % (January) to +30 % (February) between model and observations, except during March (+76 %). Sensitivity simulations using a mixed layer model (MXL/MESSy) indicated that the springtime overestimation of LBL would lead to a minor uncertainty in simulated surface ozone concentrations. However, it would lead to a significant overestimation of the dilution of black carbon aerosols at this site. Our work fills a gap in observations of local boundary layer over this complex terrain in the Himalayas, and highlights the need for year-long simultaneous measurements of boundary layer dynamics and air quality to better understand the role of lower tropospheric dynamics in pollution transport.

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