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Integration of multi-phase chemistries into a 3D photochemical transport model to improve model performances
No full textIn recent years, many studies have emphasized that the dangers of air pollutants such as O3 and particulate matter (PM) influencing premature mortality and adverse health effects. In response to these issues, governments have implemented emission control strategies based on the result of air quality models. However, such mitigating air pollutant policies proves to be highly ineffective due to uncertainties in model simulation. These findings suggest a critical need for further development focused on enhancing model performance and reliability. In this context, we developed updated Community Multiscale Air Quality (CMAQ) model that incorporates multiphase reactions and updated emissions associated with four representative processes: (i) HONO processes, (ii) halogen processes, (iii) sulfate processes, and (iv) HO₂ processes. In particular, these four processes were selected because of their close association with the formation of air pollutants. Based on the modeling framework, we evaluate the model performance against observations, then examined the impact of the four processes on atmospheric species. First, we incorporated newly HONO processes into our modeling system to simulate accurate key atmospheric species such as O3 and PM2.5. The HONO chemistry incorporated in this study were: (i) direct HONO emissions (such as soil, traffic and soil HONO emissions); (ii) gas-phase HONO reaction; (iii) heterogeneous reactions of NO2 on aerosol and ground surfaces; (iv) renoxifications. After establishing modeling framework, we explored the impact of HONO processes on oxidant capacity (OH, HO2, and O3), as well as particulate matter concentrations. As a result, the updated model showed improvements in the mixing ratios of both HONO and O3 simulated compared to observed mixing ratios with enhanced statistical metrics. Secondly, we investigated the influence of halogen radicals (Cl, Br, and I) on significant atmospheric species by incorporating halogen processes, including emissions of halogen compounds and 155 new gaseous-, 4 aqueous-, and 18 heterogeneous-halogen reactions, into the CMAQ model. We evaluate the updated model performance by utilizing the ClNO2 observations, and then examined the net Ox production rates (P(Ox)) in the presence of the halogen radicals. The results revealed that mixing ratios of ClNO2 simulated agreed well with observations, with the index of agreement (IOA) rising from 0.41 to 0.66. In addition, the P(Ox) increased in the land, while decreased over the ocean. Our findings highlight the critical role of halogen chemistry determining the levels of atmospheric species. Thirdly, in order to address underestimation in sulfate concentrations simulated, we developed a new parameterization of the SO2 uptake coefficient (γSO2) as a function of relative humidity, and NO2 and NH3 mixing ratios. We then evaluated the γSO2 used in this study, together with different parameterizations of γSO2 introduced in previous studies. Comparative analysis showed that our study has the best agreements with surface-observations. For example, sulfate concentrations simulated in our study increasing from 3.85 μg/m3 to 4.78 μg/m3, with the IOA increasing from 0.63 to 0.70. In addition, for extended 1-year simulations, our approach also significantly reproduced the sulfate concentrations during the spring and winter. It implied that the importance of accurate γSO2 for effective air quality management strategies. Finally, we attempted to provide a comprehensive insight into the HO2 processes in the atmosphere. From the findings in aircraft observations, we found that the mixing ratios of HO2 simulated may be strongly connected with NO distributions. In particular, for low-NO conditions (below 0.3 ppb), the mixing ratios of HO2 simulated overestimated by 6.0% due to missing removal pathways. In this context, we incorporated HO2 aerosol uptake, adopting an uptake coefficient of HO2 as 0.08, assuming no H2O2 production, which can lead to improved model performance. We also explored the impact of HO2 aerosol uptake on air pollutants depending on NO mixing ratios. As a result, this study emphasized complex interactions of HO₂ in atmospheric chemistry. In this study, we attempted to achieve three major objectives: (i) incorporate missing pathways into the CMAQ model using ‘state-of-the-art’ techniques; (ii) enhance the simulation accuracy for various substances; (iii) understand their interactions in the atmosphere. To establish the purpose, we investigated four representative atmospheric processes in terms of various perspectives. Based on the result, our findings are expected to provide a valuable opportunity to expand our knowledge on atmospheric chemistry and model development.DoctorABSTRACT i
CONTENTS iv
LIST OF FIGURE ix
LIST OF TABLES xvi
I. Introduction 1
1.1 Research Background 1
1.2 Organization of this study 4
1.3 References 5
II. Description of methodology 7
2.1 Modeling Framework 7
2.1.1 WRF simulation 7
2.1.2 CMAQ simulation 8
2.1.3 Emission 10
2.2 KORUS-AQ campaign 11
2.3 In-situ observations 12
2.4 Korean Flexible Chemistry (KFC) Editor 14
2.5 Statistical metrics 19
2.6 References 20
III. An investigation into atmospheric nitrous (HONO) processes in South Korea 22
3.1 Introduction 22
3.2 Methodology 25
3.2.1 WRF-CMAQ model configuration 25
3.2.2 Measurements 27
3.2.3 HONO sources 32
3.2.3.1 Gas Phase reactions (GAS) 32
3.2.3.2 Biomass burning emissions (BioB) 33
3.2.3.3 Traffic emissions (TRAF) 34
3.2.3.4 Soil emission (SOIL) 35
3.2.3.5 Heterogeneous reaction of NO2 on atmospheric aerosol surfaces (HET_A) 35
3.2.3.6 Heterogeneous reaction of NO2 on tree leaf and building surfaces (HET_L and HET_BD)
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3.2.3.7 Photolysis reactions (RENOx) 37
3.3 Results and Discussions 39
3.3.1 Observed vs Simulated HONO mixing ratios 39
3.3.2 Relative contribution of HONO sources 44
3.3.3 Impact of HONO processes on atmospheric species 48
3.3.3.1 Impact on atmospheric species 48
3.3.3.2 Impact on net ozone production 52
3.4 Conclusions 54
3.5 References 56
IV. Incorporation of a multiphase halogen chemistry into the Community Multiscale Air Quality (CMAQ)
model 64
4.1 Introduction 64
4.2 Methodology 66
4.2.1 Observation data 66
4.2.2 WRF-CMAQ model description 66
4.2.3 Halogen emissions 68
4.2.3.1 Anthropogenic emissions 68
4.2.3.2 Natural emissions 71
4.2.4 Halogen chemical reactions 73
4.2.4.1 Chlorine reactions 73
4.2.4.2 Bromine reactions 78
4.2.4.3 Iodine reactions 81
4.2.5 Experimental design 84
4.3 Results and Discussions 85
4.3.1 Model performances 85
4.3.1.1 Observed vs Modeled ClNO2 mixing ratios 85
4.3.1.2 Contributions to mixing ratios of ClNO2 88
4.3.1.3 Uncertainties in Cl2 91
4.3.2 Influence of the halogen chemistry on O3 mixing ratios 92
4.3.2.1 Comparative analysis at three supersites 92
4.3.2.2 Impacts of halogen processes 94
4.3.2.3 Net Ox production 97
4.3.3 Impacts of halogen chemistry on atmospheric species 100
4.4 Summary and Conclusions 104
4.5 References 106
V. A new approach for parameterization of uptake coefficient of SO2 and its impact on sulfate
concentration 110
5.1 Introduction 110
5.2 Materials and Methods 112
5.2.1 Description of WRF-CMAQ simulation 112
5.2.2 In-situ measurements 113
5.2.3 Embedded sulfate formation pathways in the CMAQ model 114
5.2.4 Heterogeneous reaction of SO2 on aerosol 116
5.3 Results and Discussions 118
5.3.1 Evaluation of biases for sulfur species in the CMAQ model 118
5.3.2 Implementation of new parameterization of γSO2 119
5.3.3 Insights into seasonal variations of sulfate concentrations 123
5.3.4 Uncertainties in sulfate formation 125
5.4 Summary 130
5.5 References 131
VI. Comprehensive insights into HO2 processes and the impact of HO2 aerosol uptake on air quality
136
6.1 Introduction 136
6.2 Methodology 138
6.2.1 Overview of WRF-CMAQ model framework 138
6.2.2 KORUS-AQ campaign 140
6.2.3 Description of HO2 aerosol loss 140
6.3 Results and Discussions 142
viii
6.3.1 Investigation of determining factor for HO2 levels 142
6.3.2 Dependence of HO2 distribution on NO mixing ratios 147
6.3.2.1 Low-NO condition 147
6.3.2.2 High-NO condition 149
6.3.3 Influence of HO2 aerosol loss on atmospheric species 151
6.3.3.1 OH, HO2, and H2O2 151
6.3.3.2 O3 152
6.3.3.3 PM2.5 156
6.4 Summary 159
6.5 References 160
VII. Summary and future study 166
7.1 Summary 166
7.2 Future study 168
7.2.1 Integration of organic aerosol chemistry 168
7.2.2 Application for different periods 168
7.2.3 Reconciliation of emission inventory 168
CURRICULUM VITA 169
ACKNOWLEDGEMENT 17
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Implementation of an updated chlorine chemistry for the Community Multiscale Air Quality (CMAQ) modeling system using Korean Flexible Chemistry (KFC) editor
No full textThe heterogeneous reaction of dinitrogen pentoxide (N2O5) and nitryl chloride (ClNO2) is a representative reaction that contributes to the activation of particles containing chlorine in the atmosphere. Chlorine from various sources such as biomass burning and sea salt is reacted with N2O5 to produce ClNO2. ClNO2 is photolyzed to produce chlorine radical. Although reactions of chlorine is diverse, yet there are some that are not reflected among reactions. Additional chlorine reactions were considered in this study because it aims to simulate the actual atmospheric chemistry. Studies of chlorine chemistry have been conducted through the chemical transport model (CTM) involving Community Multiscale Air Quality (CMAQ). However, there are omitted several factors that can alter contributions of chlorine containing particles. CMAQ modeling was conducted improved chlorine chemistry mechanism during the Korea United States Air Quality (KORUS-AQ) campaign. Meanwhile, Korean Flexible Chemistry (KFC) editor to modify chemical mechanism of CMAQ with ease have been developed. In this study, gas-phase chemistry was updated using the KFC editor to combine three homogeneous reactions of formyl chloride (ClCHO) which are considered in CB05tucl mechanism but not in SAPRC07tc. In addition, the update of heterogeneous reactions of hydrochloric acid (HCl), hypochlorous acid (HOCl), and chlorine nitrate (ClONO2) was taken into account in CMAQ. To evaluate the effect of uptake coefficient of N2O5 on the formation of ClNO2, ozone (O3), and nitrate (NO3-), sensitivity analyses of the uptake coefficient ranging from 0.0001 to 0.086 was imposed in CMAQ to show. The results of this study show how chlorine containing substances affect Cl2, ClNO2, O3, and NO3-. In addition, CMAQ-simulated results suggest which uptake coefficient is appropriate for different regions.Maste
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Development of NMVOC Emission Inventory Associated with Downstream of Petroleum Industry
No full textThe purpose of this study is to establish the non-methane volatile organic compound (NMVOC) emission inventory with “Korean speciation” from 9 sources associated with downstream of petroleum industry over South Korea. This study focused on solvent use (i.e., paint applications and offset-printing) and fugitive emission sources (i.e., oil refining, naphtha cracking, aromatic reforming, polymerization processes of high density polyethylene (HDPE) and polypropylene (PP), and gasoline storage of oil storage facilities and gas stations). Such sources are the main components of emission sources related to downstream of petroleum industry. The newly estimated emission from 9 sources was 319,153 ton/yr higher than the emission from corresponding sources of Clean Air Policy Support System (CAPSS). Especially, the emission from oil refineries was considerably increased from 56,021 to 284,071 ton/yr. To investigate the chemical speciation over South Korea, the composition of 30 compounds was obtained via HS-GC-MS analysis on solvent samples with respect to 15 applications. Also, chemical profiles for the fugitive emission sources were estimated based on material balance via chemical process model (i.e., PRO/Ⅱ) simulation. The results showed that the emissions of major chemical compounds from solvent use were xylene, toluene, and ethylbenzene, while emissions from fugitive emission sources were mainly composed of propane, n-butane, C5 alkane, C6 alkane, ethylene, propylene, and xylene. Based on Koreanspeciated NMVOC emission inventory of solvent use, ozone formation potential (OFP) and secondary organic aerosol formation potential (SOAFP) were also calculated. The analysis of OFPs and SOAFPs showed that xylene, toluene, and ethylbenzene were the major precursors of ozone and SOA formation in South Korea. This study suggests that the chemically speciated NMVOC emission inventory for South Korea is important to ⅰ) control individual compounds, ⅱ) establish air quality policies, and ⅲ) produce the input data for air quality prediction modeling.Maste
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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