On the understanding of surface ozone variability, its precursors and their associations with atmospheric conditions over the Delhi region

2021 ◽  
Vol 258 ◽  
pp. 105653
Author(s):  
Anshika ◽  
Ravi Kumar Kunchala ◽  
Raju Attada ◽  
Ramesh K. Vellore ◽  
Vijay K. Soni ◽  
...  
Keyword(s):  
Surface Ozone ◽  
Atmospheric Conditions

scholarly journals Demonstration of an off-axis parabolic receiver for near-range retrieval of lidar ozone profiles

2019 ◽  
Vol 12 (1) ◽  
pp. 363-370 ◽  
Author(s):  
Betsy M. Farris ◽  
Guillaume P. Gronoff ◽  
William Carrion ◽  
Travis Knepp ◽  
Margaret Pippin ◽  
...  
Keyword(s):  
Surface Ozone ◽  
Small Diameter ◽  
Atmospheric Conditions ◽  
Lidar System ◽  
Near Surface ◽  
Multiple Wavelengths ◽  
High Bias ◽  
Measurement Channels ◽  
Transition Study

Abstract. During the 2017 Ozone Water Land Environmental Transition Study (OWLETS), the Langley mobile ozone lidar system utilized a new small diameter receiver to improve the retrieval of near-surface signals from 0.1 to 1 km in altitude. This new receiver utilizes a single 90 ∘ fiber-coupled, off-axis parabolic mirror resulting in a compact form that is easy to align. The single reflective surface offers the opportunity to easily expand its use to multiple wavelengths for additional measurement channels such as visible wavelength aerosol measurements. Detailed results compare the performance of the receiver to both ozonesonde and in situ measurements from a UAV platform, validating the performance of the near-surface ozone retrievals. Absolute O3 differences averaged 7 % between lidar and ozonesonde data from 0.1 to 1.0 km and yielded a 2.3 % high bias in the lidar data, well within the uncertainty of the sonde measurements. Conversely, lidar O3 measurements from 0.1 to 0.2 km averaged 10.5 % lower than coincident UAV O3. A more detailed study under more stable atmospheric conditions would be necessary to resolve the residual instrument differences reported in this work. Nevertheless, this unique added capability is a significant improvement allowing for near-surface observation of ozone.

scholarly journals On the Tropospheric Ozone Variations in a Coastal Area of Southwestern Europe under a Mesoscale Circulation

2010 ◽  
Vol 49 (4) ◽  
pp. 748-759 ◽  
Author(s):  
J. A. Adame ◽  
E. Serrano ◽  
J. P. Bolívar ◽  
B. A. de la Morena
Keyword(s):  
Solar Radiation ◽  
Coastal Area ◽  
Surface Ozone ◽  
Land Breeze ◽  
Industrial Complex ◽  
Atmospheric Conditions ◽  
Air Masses ◽  
Solar Radiation Intensity ◽  
Synoptic Forcing ◽  
The Mean

Abstract It is well established that surface ozone levels are greatly affected by orography, solar radiation intensity, meteorological conditions, and the levels of their precursors. In this work, the authors study the sea–land breeze circulation in its relation with the behavior of ozone in a coastal area, located in southwestern Europe, with high levels of solar radiation and an important industrial complex emitting air pollutants. Hourly mean data over a 7-yr period (1999–2005) have been used in the study. Two patterns of sea–land breeze have been identified after analyzing 2298 days of measurements: a “pure” breeze (179 cases) and another one, called a “nonpure” breeze (284 cases), which is the resulting flow of the former and northwesterlies synoptic forcing. Among other results, the highest levels of surface ozone were observed under pure sea–land breeze, with hourly values up to 100 μg m−3 in the mean daily evolution. In contrast, for a nonpure breeze, the 24-h average daily value was lower than the corresponding one under a pure breeze by a factor of 1.16 and could reach 1.60 in representative real cases. These findings give evidence that the formation and accumulation of ozone are favored by the conditions under a pure sea–land breeze: that is, perpendicular wind directions toward the coastline, effective recirculation of air masses, and formation of ozone residual layers above the sea. Because these atmospheric conditions occur in other coastal regions in the world, the conclusions of this study could be extended to them.

scholarly journals Analysis of a summer smog episode in the Berlin-Brandenburg region with a nested atmosphere -- chemistry model

2002 ◽  
Vol 2 (4) ◽  
pp. 259-270 ◽  
Author(s):  
S. E. Bauer ◽  
B. Langmann
Keyword(s):  
Dominant Role ◽  
Surface Ozone ◽  
Model System ◽  
Complex Model ◽  
Urban Atmosphere ◽  
Ozone Production ◽  
Ozone Formation ◽  
Atmospheric Conditions ◽  
Near Surface ◽  
Summer Smog

Abstract. An analysis of a pollution episode in an urban atmosphere, using a complex model system is presented. The nested atmosphere-chemistry model system simulates the atmospheric conditions during a one week measurement campaign, called FLUMOB, in July 1994 in Berlin-Brandenburg, Germany. The analysis shows that naturally emitted hydrocarbons played the dominant role in the ozone formation in the investigated area. The composition of non-methane volatile organic compounds was made up to 70--80% by biogenically emitted hydrocarbons. During the analysed case, ozone formation was sensitive to hydrocarbon concentrations so that the ozone production was limited by the availability of hydrocarbons and thus especially by the amount which was biogenically emitted. Furthermore, it is shown that the FLUMOB episode was influenced by elevated concentrations of ozone in the free troposphere. In contrast to previous analyses, the importance of ozone produced outside of Europe is emphasized. In spite of the stagnant high pressure situation which occurred during the FLUMOB episode Germany was significantly influenced by long-range transport of ozone. This transport also influenced near surface ozone concentrations.

Projecting Future Air Quality Under Energy Transition Scenarios over the U.S. using Online-Coupled Models

2021 ◽  
Author(s):  
Yang Zhang ◽  
Kai Wang ◽  
Daniel Schuch
Keyword(s):  
Air Quality ◽  
Linear Regression ◽  
Surface Ozone ◽  
Energy Transition ◽  
Air Pollutant ◽  
Atmospheric Composition ◽  
Atmospheric Conditions ◽  
Coupled Models ◽  
Ensemble Mean ◽  
Multi Linear Regression

<p> </p><p>Online-coupled meteorology-chemistry models provide powerful tools for more realistically simulation of current and future air quality with feedbacks between atmospheric composition and meteorology that cannot be considered in offline-coupled models. In this work, several state-of-science online-coupled models are applied to generate the best possible predictions of surface ozone (O<sub>3</sub>) and fine particulate matter (PM<sub>2.5</sub>) concentrations under current emission and climate conditions. Two ensemble methods are used to further reduce the model biases and errors including a simple ensemble mean based on an average of ensemble members, and a weighted ensemble mean based on the multi-linear regression. The skills of individual models and their ensembles are evaluated using available surface network data.  Compared to individual models and the simple ensemble mean, the weighted ensemble predictions based on the multi-linear regression perform the best overall for both O<sub>3</sub> and PM<sub>2.5</sub>. The model with best performance is selected to apply for future years to project the changes in air quality under various energy transition scenarios to support the development of emission control strategies. These results illustrate the current capability of the online-coupled models and the potential of weighted ensemble in generating the best possible estimates of air pollutant concentrations under current and future atmospheric conditions. </p>

scholarly journals Nocturnal surface ozone enhancement over Portugal during winter: Influence of different atmospheric conditions

2016 ◽  
Vol 147 ◽  
pp. 109-120 ◽  
Author(s):  
Pavan S. Kulkarni ◽  
Hari Prasad Dasari ◽  
Ashish Sharma ◽  
D. Bortoli ◽  
Rui Salgado ◽  
...  
Keyword(s):  
Surface Ozone ◽  
Atmospheric Conditions

scholarly journals NOx AND O3 VARIABILITY AND ITS RELATION WITH WEATHER CONDITIONS IN IAȘI CITY

2019 ◽  
Vol 13 (2) ◽  
pp. 69-85
Author(s):  
Vlad-Alexandru AMIHĂESEI ◽  
Lucian SFÎCĂ ◽  
Liviu APOSTOL ◽  
Alina LEAHU
Keyword(s):  
Surface Ozone ◽  
Atmospheric Stability ◽  
Warm Season ◽  
Weather Conditions ◽  
Cold Season ◽  
Atmospheric Pollutants ◽  
Oxides Of Nitrogen ◽  
Atmospheric Conditions ◽  
Synoptic Conditions ◽  
Radiation Maximum

The paper presents the temporal variability of surface ozone (O3) and its precursors (oxides of nitrogen - NOx) from January 2012 to December 2015. In the same time, this study is aimed to explore the influence of the weather elements on these two major atmospheric pollutants in the area of Iași city. The maximum record of nitrogen oxides reached during the 4 analyzed years was 1200 μ/m-3 on October 27, 2015, a period of the year when atmospheric stability prevails. During the warm season (considered from May to September) the highest concentration of ozone was recorded at 155 μ/m-3. The winds direction from SSE or NNW and the winds speed greater than 2 m/s can significantly increase the concentration of the O3 and NOx respectively. Also, the stable atmospheric conditions can increase especially the concentration of the nitrogen dioxides. The statistical results illustrate a strong Pearson's correlation of surface ozone with solar radiation/maximum air temperature (r >0.5). The correlations were strongest during the summer months. Using the composite method, between warm season and cold season a difference of the pollutants concentration greater than 30 units for NOx was observed. Synoptic conditions associated with high pollution are also described.

scholarly journals Development and evaluation of the Screening Trajectory Ozone Prediction System (STOPS, version 1.0)

2015 ◽  
Vol 8 (5) ◽  
pp. 1383-1394 ◽  
Author(s):  
B. H. Czader ◽  
P. Percell ◽  
D. Byun ◽  
S. Kim ◽  
Y. Choi
Keyword(s):  
Boundary Conditions ◽  
Initial Conditions ◽  
Surface Ozone ◽  
Prediction System ◽  
Atmospheric Conditions ◽  
Detailed Chemistry ◽  
Mixing Ratios ◽  
Ozone Prediction ◽  
The Mean ◽  
Simulation Results

Abstract. A hybrid Lagrangian–Eulerian based modeling tool has been developed using the Eulerian framework of the Community Multiscale Air Quality (CMAQ) model. It is a moving nest that utilizes saved original CMAQ simulation results to provide boundary conditions, initial conditions, as well as emissions and meteorological parameters necessary for a simulation. Given that these files are available, this tool can run independently of the CMAQ whole domain simulation, and it is designed to simulate source–receptor relationships upon changes in emissions. In this tool, the original CMAQ's horizontal domain is reduced to a small sub-domain that follows a trajectory defined by the mean mixed-layer wind. It has the same vertical structure and physical and chemical interactions as CMAQ except advection calculation. The advantage of this tool compared to other Lagrangian models is its capability of utilizing realistic boundary conditions that change with space and time as well as detailed chemistry treatment. The correctness of the algorithms and the overall performance was evaluated against CMAQ simulation results. Its performance depends on the atmospheric conditions occurring during the simulation period, with the comparisons being most similar to CMAQ results under uniform wind conditions. The mean bias for surface ozone mixing ratios varies between −0.03 and −0.78 ppbV and the slope is between 0.99 and 1.01 for different analyzed cases. For complicated meteorological conditions, such as wind circulation, the simulated mixing ratios deviate from CMAQ values as a result of the Lagrangian approach of using mean wind for its movement, but are still close, with the mean bias for ozone varying between 0.07 and −4.29 ppbV and the slope varying between 0.95 and 1.06 for different analyzed cases. For historical reasons, this hybrid Lagrangian–Eulerian based tool is named the Screening Trajectory Ozone Prediction System (STOPS), but its use is not limited to ozone prediction as, similarly to CMAQ, it can simulate concentrations of many species, including particulate matter and some toxic compounds, such as formaldehyde and 1,3-butadiene.

scholarly journals Analysis of a summer smog episode in the Berlin-Brandenburg region with a nested atmosphere – chemistry model

2002 ◽  
Vol 2 (3) ◽  
pp. 789-824 ◽  
Author(s):  
S. E. Bauer ◽  
B. Langmann
Keyword(s):  
Dominant Role ◽  
Surface Ozone ◽  
Model System ◽  
Complex Model ◽  
Urban Atmosphere ◽  
Ozone Production ◽  
Ozone Formation ◽  
Atmospheric Conditions ◽  
Near Surface ◽  
Summer Smog

Abstract. An analysis of a pollution episode in an urban atmosphere, using a complex model system is presented. The nested atmosphere-chemistry model system simulates the atmospheric conditions during a one week measurement campaign, called FLUMOB, in July 1994 in Berlin-Brandenburg, Germany. The analysis shows that naturally emitted hydrocarbons played the dominant role in the ozone formation in the investigated area. The composition of non-methane volatile organic compounds was made up to 70--80% by biogenically emitted hydrocarbons. During the analysed case, ozone formation was sensitive to hydrocarbon concentrations so that the ozone production was limited by the availability of hydrocarbons and thus especially by the amount which was biogenically emitted. Furthermore, it is shown that the FLUMOB episode was influenced by elevated concentrations of ozone in the free troposphere. In contrast to previous analyses, the importance of ozone produced outside of Europe is emphasized. In spite of the stagnant high pressure situation which occurred during the FLUMOB episode Germany was significantly influenced by long-range transport of ozone. This transport also influenced near surface ozone concentrations.

Selective Corrosion of brazed joint between BNi-2 filler metal and stainless steel 316

1996 ◽  
Vol 54 ◽  
pp. 218-219
Author(s):  
H. S. Kim ◽  
R. U. Lee
Keyword(s):  
Stainless Steel ◽  
Filler Metal ◽  
Surface Preparation ◽  
Optical Microscope ◽  
Heating Element ◽  
Incomplete Fusion ◽  
Atmospheric Conditions ◽  
Leak Test ◽  
High Temperature Side ◽  
Inconel 600

A heating element/electrical conduit assembly used in the Orbiter Maneuvering System failed a leak test during a routine refurbishment inspection. The conduit, approximately 100 mm in length and 12 mm in diameter, was fabricated from two tubes and braze-joined with a sleeve. The tube on the high temperature side (heating element side) and the sleeve were made of Inconel 600 and the other tube was stainless steel (SS) 316. For the filler metal, a Ni-Cr-B brazing alloy per AWS BNi-2, was used. A Helium leak test spotted the leak located at the joint between the sleeve and SS 316 tubing. This joint was dissected, mounted in a plastic mold, polished, and examined with an optical microscope. Debonding of the brazed surfaces was noticed, more pronounced toward the sleeve end which was exposed to uncontrolled atmospheric conditions intermittently. Initially, lack of wetting was suspected, presumably caused by inadequate surface preparation or incomplete fusion of the filler metal. However, this postulation was later discarded based upon the following observations: (1) The angle of wetting between the fillet and tube was small, an indication of adequate wetting, (2) the fillet did not exhibit a globular microstructure which would be an indication of insufficient melting of the filler metal, and (3) debonding was intermittent toward the midsection of the sleeve.

Recent Progress In High-Resolution Shadowing For Biological Transmission Electron Microscopy

1990 ◽  
Vol 48 (1) ◽  
pp. 510-511 ◽  
Author(s):  
Heinz Gross ◽  
Katarina Krusche ◽  
Peter Tittmann
Keyword(s):  
Heavy Metal ◽  
High Resolution ◽  
Freeze Drying ◽  
Atmospheric Conditions ◽  
Vacuum Equipment ◽  
Transmission Electron ◽  
Gas Atmosphere ◽  
Gas Molecules ◽  
Residual Gas ◽  
Backing Layer

Freeze-drying followed by heavy metal shadowing is a long established and straight forward approach to routinely study the structure of dehydrated macromolecules. Very thin specimens such as isolated membranes or single macromolecules are directly adsorbed on C-coated grids. After rapid freezing the grids are transferred into a suitable vacuum equipment for freeze-drying and heavy metal shadowing.To improve the resolution power of shadowing films we introduced shadowing at very low specimen temperature (−250°C). To routinely do that without the danger of contamination we developed in collaboration with Balzers an UHV (p≤10-9 mbar) machine (BAF500K, Fig.2). It should be mentioned here that at −250°C the specimen surface acts as effective cryopump for practically all impinging residual gas molecules from the residual gas atmosphere.Common high resolution shadowing films (Pt/C, Ta/W) have to be protected from alterations due to air contact by a relatively thick C-backing layer, when transferred via atmospheric conditions into the TEM. Such an additional C-coat contributes disturbingly to the contrast at high resolution.

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