What have we missed when studying the impact of aerosols on surface ozone via changing photolysis rates?

Abstract. Previous studies have emphasized that the decrease in photolysis rate at the surface induced by the light extinction of aerosols could weaken ozone photochemistry and then reduce surface ozone. However, quantitative studies have shown that weakened photochemistry leads to a much greater reduction in the net chemical production of ozone, which does not match the reduction in surface ozone. This suggests that in addition to photochemistry, some other physical processes related to the variation of ozone should also be considered. In this study, the Weather Research and Forecasting with Chemistry (WRF-Chem) model coupled with the ozone source apportionment method was applied to determine the mechanism of ozone reduction induced by aerosols over central East China (CEC). Our results showed that weakened ozone photochemistry led to a significant reduction in ozone net chemical production, which occurred not only at the surface but also within the lowest several hundred meters in the planetary boundary layer (PBL). Meanwhile, a larger ozone gradient was formed in the vertical direction, which led to the high concentrations of ozone aloft being entrained by turbulence from the top of the PBL to the surface and partly counteracting the reduction in surface ozone. In addition, contribution from dry deposition was weakened due to the decrease in surface ozone concentration. The reduction in the ozone's sink also slowed down the rate of the decrease in surface ozone. Ozone in the upper layer of the PBL was also reduced, which was induced by much ozone aloft being entrained downward. Therefore, by affecting the photolysis rate, the impact of aerosols was a reduction in ozone not only at the surface but also throughout the entire PBL during the daytime over CEC in this study. The ozone source apportionment results showed that 41.4 %–66.3 % of the reduction in surface ozone came from local and adjacent source regions, which suggested that the impact of aerosols on ozone from local and adjacent regions was more significant than that from long-distance regions. The results also suggested that while controlling the concentration of aerosols, simultaneously controlling ozone precursors from local and adjacent source regions is an effective way to suppress the increase in surface ozone over CEC at present.

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What have we missed when studying the impact of aerosols on surface ozone via changing photolysis rates?

10.5194/acp-2020-140 ◽

2020 ◽

Author(s):

Jinhui Gao ◽

Ying Li ◽

Bin Zhu ◽

Bo Hu ◽

Lili Wang ◽

...

Keyword(s):

Source Apportionment ◽

Surface Ozone ◽

Vertical Direction ◽

Light Extinction ◽

Chemical Production ◽

Long Distance ◽

Source Regions ◽

Photolysis Rate ◽

Ozone Photochemistry ◽

The Impact

Abstract. Previous studies have emphasized that the decrease in photolysis rate at the surface induced by the light extinction of aerosols could weaken ozone photochemistry and then reduce surface ozone. However, quantitative studies have shown that weakened photochemistry leads to a much greater reduction in the net chemical production of ozone, which does not match the reduction in surface ozone. This suggested that in addition to photochemistry, some other physical processes related to the variation of ozone should also be considered. In this study, the Weather Research and Forecasting with Chemistry (WRF-Chem) model coupled with the ozone source apportionment method was applied to determine the mechanism of ozone reduction induced by aerosols over Central East China (CEC). Our results showed that weakened ozone photochemistry led to a significant reduction in ozone net chemical production, which occurred not only at the surface but also within the lowest several hundred meters in the planetary boundary layer (PBL). Meanwhile, a larger ozone gradient was formed in vertical direction, which led to the high concentrations of ozone aloft being entrained by turbulence from the top of the PBL to the surface and partly counteracting the reduction in surface ozone. In addition, ozone in the upper layer of the PBL was also reduced, which was also induced by much ozone aloft being entrained downward. Therefore, by affecting the photolysis rate, the impact of aerosols was a reduction in ozone not only at the surface but also throughout the entire PBL during the daytime over the CEC in this study. The ozone source apportionment results showed that 41.4 %–66.3 % of the reduction in surface ozone came from local and adjacent source regions, which suggested that the impact of aerosols on ozone from local and adjacent regions was more significant than that from long-distance regions. The results also suggested that while controlling the concentration of aerosols, simultaneously controlling ozone precursors from local and adjacent source regions is an effective way to suppress the increase in surface ozone over CEC at present.

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Avoiding high ozone pollution in Delhi, India

Faraday Discussions ◽

10.1039/d0fd00079e ◽

2021 ◽

Cited By ~ 1

Author(s):

Ying Chen ◽

Gufran Beig ◽

Scott Archer-Nicholls ◽

Will Drysdale ◽

W. Joe F. Acton ◽

...

Keyword(s):

Air Quality ◽

Surface Ozone ◽

Light Extinction ◽

Ozone Pollution ◽

Ozone Photochemistry

Quantify the influence of aerosol light extinction on surface ozone photochemistry, highlight controlling VOC for improving air quality in Delhi.

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

Atmospheric Chemistry and Physics ◽

10.5194/acp-18-7081-2018 ◽

2018 ◽

Vol 18 (10) ◽

pp. 7081-7094 ◽

Cited By ~ 13

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.

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

Atmospheric Chemistry and Physics ◽

10.5194/acp-10-11305-2010 ◽

2010 ◽

Vol 10 (22) ◽

pp. 11305-11322 ◽

Cited By ~ 56

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.

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The influence of weather-driven processes on tropospheric ozone

10.5194/acp-2021-584 ◽

2021 ◽

Author(s):

Tamara Emmerichs ◽

Bruno Franco ◽

Catherine Wespes ◽

Vinod Kumar ◽

Andrea Pozzer ◽

...

Keyword(s):

Atmospheric Chemistry ◽

Dry Deposition ◽

Tropospheric Ozone ◽

Surface Ozone ◽

Air Pollutant ◽

Chemical Production ◽

Ozone Monitoring Instrument ◽

Near Surface ◽

The Impact

Abstract. Near-surface ozone is an harmful air pollutant, which is determined to a considerable extent by weather-controlled processes, and may be significantly impacted by water vapour forming complexes with peroxy radicals. The role of water in the reaction of HO2 radical with nitrogen oxides is known from the literature, and in current models the water complex is considered by assuming a linear dependence on water concentrations. In fact, recent experimental evidence has been published, showing the significant role of water on the kinetics of one of the most important reaction for ozone chemistry, namely NO2 + OH. Here, the available kinetic data for the HOx + NOx reactions have been included in the atmospheric chemistry model ECHAM5/MESSy (EMAC) to test its global significance. Among the modified kinetics, the newly added HNO3 channel from HO2 + NO, dominates, significantly reducing NO2. A major removal process of near-surface ozone is dry deposition accounting for 20 % of the total tropospheric ozone loss mostly occurring over vegetation. However, parameterizations for modelling dry deposition represent a major source of uncertainty for tropospheric ozone simulations. This potentially belongs to the reasons why global models, such as EMAC used here, overestimate ozone with respect to observations. In fact, the employed parameterization is hardly sensitive to local meteorological conditions (e.g., humidity) and lacks non-stomatal deposition. In this study, a dry deposition scheme including these features have been used in EMAC, affecting not only the deposition of ozone but of its precursors, resulting in lower chemical production of ozone. Additionally, we improved the emissions of isoprene and nitrous acid (HONO). Namely, for isoprene emissions we have accounted for the impact of drought stress which confers a higher model sensitivity to meteorology leading to reduced annual emissions down to 32 %. For HONO, we have implemented soil emissions, which depend on soil moisture and thus on precipitation. We estimate for the first time a global source strength of 7 Tg(N) a−1. Furthermore, the usage of a parameterization for the production of lightning NOx that depends on cloud top height contributes to a more realistic representation of NO2 columns over remote oceans with respect to the satellite measurements of the Ozone Monitoring Instrument (OMI). The combination of all the model modifications reduces the simulated global ozone burden by ≈ 20 % to 337 Tg, which is in better agreement with recent estimates. By comparing simulation results with measurements from the Infrared Atmospheric Sounding Interferometer (IASI) and the Tropospheric Ozone Assessment Report (TOAR) databases (of 2009) we demonstrate an overall reduction of the ozone bias by a factor of 2.

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The impact of inhomogeneous emissions and topography on ozone photochemistry in the vicinity of Hong Kong Island

Atmospheric Chemistry and Physics ◽

10.5194/acp-21-3531-2021 ◽

2021 ◽

Vol 21 (5) ◽

pp. 3531-3553

Author(s):

Yuting Wang ◽

Yong-Feng Ma ◽

Domingo Muñoz-Esparza ◽

Cathy W. Y. Li ◽

Mary Barth ◽

...

Keyword(s):

Hong Kong ◽

Surface Ozone ◽

Chemical Species ◽

Convective Boundary ◽

Large Eddy ◽

Segregation Effect ◽

Chemical Scheme ◽

Ozone Photochemistry ◽

The Impact ◽

Secondary Chemical

Abstract. Global and regional chemical transport models of the atmosphere are based on the assumption that chemical species are completely mixed within each model grid box. However, in reality, these species are often segregated due to localized sources and the influence of topography. In order to investigate the degree to which the rates of chemical reactions between two reactive species are reduced due to the possible segregation of species within the convective boundary layer, we perform large-eddy simulations (LESs) in the mountainous region of Hong Kong Island. We adopt a simple chemical scheme with 15 primary and secondary chemical species, including ozone and its precursors. We calculate the segregation intensity due to inhomogeneity in the surface emissions of primary pollutants and due to turbulent motions related to topography. We show that the inhomogeneity in the emissions increases the segregation intensity by a factor of 2–5 relative to a case in which the emissions are assumed to be uniformly distributed. Topography has an important effect on the segregation locally, but this influence is relatively limited when considering the spatial domain as a whole. In the particular setting of our model, segregation reduces the ozone formation by 8 %–12 % compared to the case with complete mixing, implying that the coarse-resolution models may overestimate the surface ozone when ignoring the segregation effect.

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The methodological approach for the determination of the pressure of artificial raindrops as a question of the theory of splash soil erosion

Melioration and Water Management ◽

10.32962/0235-2524-2019-1-24-28 ◽

2020 ◽

pp. 24-28

Author(s):

Mihail Zver'kov

Keyword(s):

Block Diagram ◽

Methodological Approach ◽

Control Measures ◽

Soil Conditions ◽

Effective Pressure ◽

Long Distance ◽

Splash Erosion ◽

Rain Drops ◽

Artificial Rain ◽

The Impact

To the article the results of the theoretical and experimental researches are given on questions of estimates of the dynamic rate effect of raindrop impact on soil. The aim of this work was to analyze the current methods to determine the rate of artificial rain pressure on the soil for the assessment of splash erosion. There are the developed author’s method for calculation the pressure of artificial rain on the soil and the assessment of splash erosion. The study aims to the justification of evaluation methods and the obtaining of quantitative characteristics, prevention and elimination of accelerated (anthropogenic) erosion, the creation and the realization of the required erosion control measures. The paper considers the question of determining the pressure of artificial rain on the soil. At the moment of raindrops impact, there is the tension in the soil, which is called vertical effective pressure. It is noted that the impact of rain drops in the soil there are stresses called vertical effective pressure. The equation for calculation of vertical effective pressure is proposed in this study using the known spectrum of raindrops. Effective pressure was 1.4 Pa for the artificial rain by sprinkler machine «Fregat» and 5.9 Pa for long distance sprinkler DD-30. The article deals with a block diagram of the sequence for determining the effective pressure of rain drops on the soil. This diagram was created by the author’s method of calculation of the effective pressure of rain drops on the soil. The need for an integrated approach to the description of the artificial rain impact on the soil is noted. Various parameters characterizing drop erosion are considered. There are data about the mass of splashed soil in the irrigation of various irrigation machinery and installations. For example, the rate (mass) of splashed soil was 0.28…0.78 t/ha under irrigation sprinkler apparatus RACO 4260–55/701C in the conditions of the Ryazan region. The method allows examining the environmental impact of sprinkler techniques for analyzes of the pressure, caused by raindrops, on the soil. It can also be useful in determining the irrigation rate before the runoff for different types of sprinkler equipment and soil conditions.

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DISCRESSION OF THE SAMPLE RESORTS POLICE IN THE IMPLEMENTATION OF ADMINISTRATIVE LAW PERSPECTIVE INVESTIGATION

Legal Standing Jurnal Ilmu Hukum ◽

10.24269/ls.v4i2.3065 ◽

2020 ◽

Vol 4 (2) ◽

pp. 147

Author(s):

Tamrin Muchsin ◽

Sri Sudono Saliro ◽

Nahot Tua Parlindungan Sihaloho ◽

Sardjana Orba Manullang

Keyword(s):

Empirical Research ◽

Qualitative Method ◽

Government Regulation ◽

Sampling Technique ◽

Administrative Law ◽

Criminal Investigation ◽

Accurate Data ◽

Long Distance ◽

The Impact ◽

Depth Interviews

It is still found that investigating officers do not have an S1 degree or equivalent in thejurisdiction of the Sambass Resort Police as mandated in PP No. 58 of 2010 concerningAmendments to Government Regulation Number 27 of 1983 concerning theImplementation of KUHAP article 2A paragraph (1) letter a. If the requirements ofinvestigators are not fulfilled, there will automatically be limits of authority, includingthe inability to issue investigation orders, detention warrants and other administrativeletters. This study used a qualitative method with juridical empirical research. Toobtain accurate data, purposive sampling technique was used, and primary datacollection by conducting in-depth interviews. The research results found, among others:first, discretion regarding the administration of investigations in the jurisdiction of theSambas Resort Police for the Sambas District Police who do not have investigatingofficers who meet the requirements, is then taken over by the Head of the CriminalInvestigation Unit as the supervisor of the integrated criminal investigation function.Second, the impact of an integrated investigation administration causes the time tocarry out investigations to be slow due to the long distance between the Sector Policeand the Resort Police.

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45. Education at distance: Broadcasting ECG rounds to Southeastern Ontario (BESO Project). An innovative approach for teaching electrocardiography

Clinical & Investigative Medicine ◽

10.25011/cim.v30i4.2805 ◽

2007 ◽

Vol 30 (4) ◽

pp. 51 ◽

Cited By ~ 2

Author(s):

A. Baranchuk ◽

G. Dagnone ◽

P. Fowler ◽

M. N. Harrison ◽

L. Lisnevskaia ◽

...

Keyword(s):

Health Care ◽

Real Time ◽

Digital Signal ◽

Teaching Methodology ◽

Care Providers ◽

Long Distance ◽

Medicine Clerkship ◽

Time Problem ◽

The Impact ◽

Ecg Interpretation

Electrocardiography (ECG) interpretation is an essential skill for physicians as well as for many other health care professionals. Continuing education is necessary to maintain these skills. The process of teaching and learning ECG interpretation is complex and involves both deductive mechanisms and recognition of patterns for different clinical situations (“pattern recognition”). The successful methodologies of interactive sessions and real time problem based learning have never been evaluated with a long distance education model. To evaluate the efficacy of broadcasting ECG rounds to different hospitals in the Southeastern Ontario region; to perform qualitative research to determine the impact of this methodology in developing and maintaining skills in ECG interpretation. ECG rounds are held weekly at Kingston General Hospital and will be transmitted live to Napanee, Belleville, Oshawa, Peterborough and Brockville. The teaching methodology is based on real ECG cases. The audience is invited to analyze the ECG case and the coordinator will introduce comments to guide the case through the proper algorithm. Final interpretation will be achieved emphasizing the deductive process and the relevance of each case. An evaluation will be filled out by each participant at the end of each session. Videoconferencing works through a vast array of internet LANs, WANs, ISDN phone lines, routers, switches, firewalls and Codecs (Coder/Decoder) and bridges. A videoconference Codec takes the analog audio and video signal codes and compresses it into a digital signal and transmits that digital signal to another Codec where the signal is decompressed and retranslated back into analog video and audio. This compression and decompression allows large amounts of data to be transferred across a network at close to real time (384 kbps with 30 frames of video per second). Videoconferencing communication works on voice activation so whichever site is speaking has the floor and is seen by all the participating sites. A continuous presence mode allows each site to have the same visual and audio involvement as the host site. A bridged multipoint can connect between 8 and 12 sites simultaneously. This innovative methodology for teaching ECG will facilitate access to developing and maintaining skills in ECG interpretation for a large number of health care providers. Bertsch TF, Callas PW, Rubin A. Effectiveness of lectures attended via interactive video conferencing versus in-person in preparing third-year internal medicine clerkship students for clinical practice examinations. Teach Learn Med 2007; 19(1):4-8. Yellowlees PM, Hogarth M, Hilty DM. The importance of distributed broadband networks to academic biomedical research and education programs. Acad Psychaitry 2006;30:451-455

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The Effect of Repeated Whole-Body Cryotherapy on Sirt1 and Sirt3 Concentrations and Oxidative Status in Older and Young Men Performing Different Levels of Physical Activity

Antioxidants ◽

10.3390/antiox10010037 ◽

2020 ◽

Vol 10 (1) ◽

pp. 37

Author(s):

Gabriela Wojciak ◽

Jadwiga Szymura ◽

Zbigniew Szygula ◽

Joanna Gradek ◽

Magdalena Wiecek

Keyword(s):

Physical Activity ◽

Young Men ◽

Oxidative Status ◽

Whole Body ◽

Stress Index ◽

Blood Levels ◽

Long Distance ◽

Antioxidant Defence ◽

Whole Body Cryotherapy ◽

The Impact

Background: The activity of antioxidant enzymes and sirtuins (Sirt) decreases along with age, which is counteracted by aerobic training. Sirtuins increase antioxidant defence. Whole-body cryotherapy (WBC) increases total antioxidant capacity (TAC) in young men. The aim of our study was to assess the impact of 24 WBC treatments on the blood concentration of selected sirtuins and the level of antioxidant defence as well as oxidative stress index of training and non-training men depending on age. Methods: The study involved 40 males. In each group, there were 10 non-training older and young men (60 NTR and 20 NTR), and 10 older and young long-distance runners (60 TR, 20 TR). During an 8-week period, participants underwent 24 WBC treatments (3 min −130 °C), which were performed three times a week (Monday, Wednesday, Friday). The concentrations of Sirt1, Sirt3, TAC, total oxidative status and the activity of superoxide dismutase (SOD), catalase and glutathione peroxidase (GPx) in the blood were determined before 1 WBC and after 1 WBC, 12 WBC and 24 WBC. Results: After 1 WBC, the activity of GPx and the concentration of Sirt1 and TAC in 60 TR and TAC in 60 NTR increased. After 12 WBC, the level of Sirt1 in 20 NTR and SOD in 20 TR increased. After 24 WBC, the level of Sirt1 increased in 60 TR and in 20 NTR, Sirt3 in 60 TR and SOD in 20 TR. Conclusions: Cryogenic temperatures increase blood levels of Sirt1 and Sirt3 and systemic antioxidant defence in men, but the effect is dependent on age, level of performed physical activity and the number of applied treatments.

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