Evaluating the Performance of a Regional-Scale Photochemical Modelling System: Part I Ozone Predictions

We present a detailed evaluation of the seasonal performance of the Community Multiscale Air Quality (CMAQ) modelling system and the PSU/NCAR meteorological model coupled to a new Numerical Emission Model for Air Quality (MNEQA). The combined system simulates air quality at a fine resolution (3 km as horizontal resolution and 1 h as temporal resolution) in north-eastern Spain, where problems of ozone pollution are frequent. An extensive database compiled over two periods, from May to September 2009 and 2010, is used to evaluate meteorological simulations and chemical outputs. Our results indicate that the model accurately reproduces hourly and 1-h and 8-h maximum ozone surface concentrations measured at the air quality stations, as statistical values fall within the EPA and EU recommendations. However, to further improve forecast accuracy, three simple bias-adjustment techniques mean subtraction (MS), ratio adjustment (RA), and hybrid forecast (HF) based on 10 days of available comparisons are applied. The results show that the MS technique performed better than RA or HF, although all the bias-adjustment techniques significantly reduce the systematic errors in ozone forecasts

The application of an Eulerian chemical and transport model (CMAQ) at fine scale resolution to the UK

Present-day numerical air quality models are considered essential tools for predicting future air pollutant concentrations and depositions, contributing to the development of new effective strategies for the control and the reduction of pollutant emissions. They simulate concentrations and depositions of pollutants on a wide range of scales (global, national, urban scale) and they are used for identifying critical areas, integrating measurements and achieving a deeper scientific understanding of the physical and chemical processes involving air pollutants in the atmosphere. The use of comprehensive air quality models started in the late 1970s and since then their development has increased rapidly, hand in hand with the rapid increase in computational resources. Today more and more complex and computationally expensive numerical models are available to the scientific community. One of these tools is the Community Multi-Scale Air Quality System (CMAQ), developed in the 1990s by the US Environmental Protection Agency (EPA) and currently widely applied across the world for air pollution studies. This work focuses on the application of CMAQ to the United Kingdom, for estimating concentrations and depositions of acidifying pollutants (NOX, NHX, SOX) on a national scale. The work is divided into seven chapters, the first one describing the main issues related to the emission and dispersion in the atmosphere of acidifying species. It also includes a brief overview of the main international policies signed in the last thirty years in order to reduce the problem of acidification in Europe, as well as a brief description of some models mentioned in this thesis. The second one describes the main features of CMAQ and addresses some issues such as the use of a nesting process for achieving temporally and spatially resolved boundary concentrations, and the implementation of the model on parallel machines, essential for reducing the simulation computing time. It also describes how this study is part of a wider context, which includes the application of CMAQ in the United Kingdom by other users with different scientific purposes (aerosols processes, air quality in the urban area of London, contribution of UK power stations to concentrations and depositions etc.). The third part of the thesis focuses on the application and evaluation over the United Kingdom of the 5th Generation Mesoscale Model MM5, used for providing 3D meteorological input fields to CMAQ. This study was performed assuming that an accurate representation of depositions and concentrations of chemical species cannot be achieved without a good estimate of the meteorological parameters involved in most of the atmospheric processes (transport, photochemistry, aerosol processes, cloud processes etc.). The fourth part of the thesis describes the preliminary implementation of the Sparse Matrix Operational Kernel Emission System (SMOKE) in the United Kingdom. The processor provides input emissions to CMAQ. The use of SMOKE is usually avoided in CMAQ applications of outside America, and CMAQ input emission files are prepared by the application of other software. The reason is that the model requires radical changes for being applied outside Northern and Central America. Some of these changes have been made in this study such as the adaptation of the European emission inventory EMEP and the UK National Inventory NAEI to the modelling system for point and area sources, the introduction of new European emission temporal profiles in substitution of the American ones and the introduction of new geographical references for the spatial allocation of emissions. In the fifth chapter the results of CMAQ application over the UK are discussed. The study focuses on NOX, SO2, NH3 and + 4 NH . Maps of concentration are presented and modelled data are compared to measurements from two different air quality networks in the UK. An analysis of the performance of CMAQ over the UK is also performed. In the final chapter an annual inter-comparison between CMAQ and the Lagrangian transport model FRAME is carried out. Maps of annual wet deposition fluxes of NHX, NOY and SOX for year 1999 are presented. The results of both models are compared to one another and they are also compared to values from the UK official data set CBED. Finally, the last chapter suggests the work that has to be done in the future with CMAQ and it summarizes the conclusions

Effects of 2000-2050 Global Climate Change on Ozone and Particulate Matter Air Quality in the United States Using Models-3/CMAQ System

The Models-3/Community Multi-scale Air Quality modeling system (CMAQ), coupled with Goddard Institute for Space Studies (GISS) atmospheric General Circulation Model (GCM), fifth Generation Mesoscale Model system (MM5), and Goddard Earth Observing System-CHEMistry (GEOS-Chem), was used to simulate atmospheric concentration of ozone and particulate matter over the continental United States 12-km and 36-km (CONUS) domains at year 2000 and year 2050. In the study, GISS GCM model outputs interfaced with MM5 were utilized to supply the current and future meteorological conditions for CMAQ. The conventional CMAQ profile initial and boundary conditions were replaced by time-varied and layer-varied GEOS-Chem outputs. The future emission concentrations were estimated using year 2000 based emissions with emission projections suggested by the IPCC A1B scenario. Multi-scenario statistical analyses were performed to investigate the effects of climate change and change of anthropogenic emissions toward 2050. The composite effects of these changes were broken down into individual effects and analyzed on three distinct regions (i.e., Midwest, Northeast and Southeast). The results of CMAQ hourly and 8-hour average concentrations indicate the maximum ozone concentration in the Midwest is increased slightly from year 2000 to year 2050, as a result of increasing average and maximum temperatures by 2 to 3 degrees Kelvin. In converse, there is an observed reduction of surface ozone concentration in the Southeast caused by the decrease in solar radiation. For the emission reduction scenario, the decline of anthropogenic emissions causes reductions of both ozone and PM2.5 for all regions. The emission reduction has compensated the effect of increasing temperature. The overall change on the maximum daily 8-hr ozone and average PM2.5 concentrations in year 2050 were estimated to be 10% and 40% less than the values in year 2000, respectively. The modeling results indicates the effect of emissions reduction has greater impact than the effect of climate change

Air pollution forecasts: An overview

© 2018 by the authors. Licensee MDPI, Basel, Switzerland. Air pollution is defined as a phenomenon harmful to the ecological system and the normal conditions of human existence and development when some substances in the atmosphere exceed a certain concentration. In the face of increasingly serious environmental pollution problems, scholars have conducted a significant quantity of related research, and in those studies, the forecasting of air pollution has been of paramount importance. As a precaution, the air pollution forecast is the basis for taking effective pollution control measures, and accurate forecasting of air pollution has become an important task. Extensive research indicates that the methods of air pollution forecasting can be broadly divided into three classical categories: statistical forecasting methods, artificial intelligence methods, and numerical forecasting methods. More recently, some hybrid models have been proposed, which can improve the forecast accuracy. To provide a clear perspective on air pollution forecasting, this study reviews the theory and application of those forecasting models. In addition, based on a comparison of different forecasting methods, the advantages and disadvantages of some methods of forecasting are also provided. This study aims to provide an overview of air pollution forecasting methods for easy access and reference by researchers, which will be helpful in further studies

Evaluating Surface Concentrations of NO2 and O3 in Urban and Rural Regions by Combining Chemistry Transport Modelling with Surface Measurements

A base case modelling investigation was conducted to explore the chemical and physical behaviour of ground-level ozone (O3) and its precursor nitrogen dioxide (NO2) in Ontario using the U.S. Environmental Protection Agency (EPA) Community Multiscale Air Quality (CMAQ) model. Two related studies were completed to evaluate the performance of CMAQ in reproducing the behaviour of these species in both rural and urban environments by comparing to surface measurements collected by the Ontario Ministry of the Environment (MOE) network of air quality stations. The first study was a winter examination and the second study was conducted for a period during the summer of the same year. The municipality of North Bay was used to represent a rural setting given its smaller population relative to the city of Ottawa which was the base of the urban site. Statistical and graphical analyses were used to validate the model output. CMAQ was found to replicate the spatial variation of O3 and NO2 over the domain in both the winter and summer, but showed some difficulty in simulating the temporal allocation of the species. Validation statistics for North Bay and Ottawa showed overall O3 mean biases (MB) of 3.35 ppb and 2.25 ppb, respectively, and overall NO2 MB of -8.75 ppb and -4.37 ppb, respectively for the winter. Summer statistics generated O3 MB of 4.66 ppb (North Bay) and 10.05 ppb (Ottawa) while both MB for NO2 were between -2.20 ppb to -2.55 ppb. Graphical analysis showed that the model was not able to reproduce the lower levels of O3, especially at night, or the higher levels of NO2 during the day at the North Bay site for either season. This was expected since the comparisons were made between point measurements and 36 km grid-averaged model results. The presence of high amounts of NO2 emissions local to the monitoring sites compared to the levels represented in the emissions inventory may also be a contributing factor. The simulations for Ottawa demonstrated better agreement between model results and measurements as CMAQ provided a more accurate reproduction of both the higher and lower mixing ratios of O3 and NO2 during the winter and summer seasons. Results indicate that CMAQ is able to simulate urban environments better than rural ones

Study of Ozone Sensitivity to Precursors at High Spatial Resolution Using the Modified CMAQ-ADJ Model

In this thesis, I apply the adjoint for the Community Multiscale Air Quality model (hereafter CMAQ-ADJ) in a high spatial resolution study of the sensitivity of ozone to several of its precursors in the regions surrounding the Great Lakes. CMAQ-ADJ was originally developed for low spatial resolution applications. In order to use it in high spatial resolution (12 km) studies, it was necessary to resolve a conflict between the pre-set fixed output time step interval in CMAQ-ADJ and the CMAQ-calculated irregular synchronization time-step and also to modify the meteorological interface for the backward model integrations. To increase computation efficiency, the chemistry time-step in the modified CMAQ-ADJ is checkpointed instead of being re-calculated in the backward part of the model as before. I used the modified model to analyze the sensitivity of ozone to precursor species for cases of assumed high ozone episode in two target locations in southwestern and east-central Ontario. The studies examined the influence of pre-existing ozone, NO, CO, anthropogenic volatile organic compounds (VOCs) and isoprene on ozone level changes for the 69 hours immediately preceding the assumed high ozone event. The results are dominated by the long-distance advection, local meteorology (lake breezes), air temperature, the underlying surface features, and emissions in the pollutant pathway. Both production and titration of ozone by NOx is evident at different times and locations in the simulations. The industrial Midwest U.S. and Ohio Valley have been shown to be an important source of anthropogenic emission of NO and most VOCs that contribute to high ozone events in southwestern and east-central Ontario. Isoprene from the northern forest suppresses ozone in both target regions, with a greater magnitude in east-central Ontario. The response of ozone level in the two selected receptor regions in Ontario to different VOCs depends on the type of VOC, the time and location they are emitted, and the air temperature. Increasing VOC emissions in urban areas such as Toronto and Ottawa in the morning can enhance the ozone level by late afternoon. Increasing VOCs except ethylene and formaldehyde in regions with large VOC/NOx ratio in the morning tends to suppress the ozone level by late afternoon. Among all the species examined, NO has the largest impact on the target ozone level changes. CO is very unlikely to significantly influence the ozone level changes in southwestern or east-central Ontario

Low Emission Zone Study İn İstanbul By Using Models-3/cmaq Framework

Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, Yüksek LisansM.Sc. (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, MERVE GÖKGÖZ ERGÜLIstanbul is the most populated city of Turkey as well as one of the mega cities of the world. Due to growing population and economy, city has been experiencing the problems of air pollution. There are many studies about air pollution effects on human health in the literature. Road transport emissions are released in areas where people live intensively, therefore these emissions are important for public health. This thesis aims to identify and quantify the measures to be taken to prevent traffic-related air pollution by using WRF meteorology model and CMAQ chemistry and transport model. This study presents the first Low Emission Zone study in Istanbul by using modeling and highlights the requirements of Low Emission Zone establishment. Istanbul-specific inventory includes main anthropogenic sources on 2 km horizontal and hourly temporal resolution. Road transport emissions were obtained from COPERT emission model. Emission model results reveal that on-road traffic emissions are the main source for most of the pollutants such as CO, NMVOC and NOx, industrial combustion is responsible for high amount of SO2 emissions and solvent use and traffic are the main participants for NMVOC emissions. The spatial distribution of air pollutants has proved that the highest concentrations occur at the places where emission sources are located. But uncertainties may be occur due to the activity data, emission factors and temporal profiles used in this thesis. WRF model was run for a 11-day period, includes PM concentrations are mostly higher than EU limit value (50μg/m3), from November 2 to November 12, 2010. Model run results from the WRF simulation were compared with observations from Ataturk Airport and Goztepe air quality stations. According to statistical and time plot results WRF has captured surface temperature successfully. But this performance can be further improved by changing physical parameters of WRF. The results from the CMAQ model were compared with Aksaray air quality station based on PM10 concentrations. The statistical performance of model shows low correlation with the observations. Differences between model with measurement results can arise from many causes such as; uncertainty in the meteorological model and COPERT model, improper boundary conditions and temporal profiles and measurement errors. In order to limit traffic related air pollutants, methods and regions which have high density of population and work places were determined. Based on these criteria Historical Peninsula, Kadikoy and Maslak were selected as candidates. When transport sector emissions were reduced by 30% and given to DUMAN model, Historical Peninsula has demonstrated most significant response which is 10μg/m3 reduction in PM10 hourly concentration. Then, effect of each method on PM levels was examined by using literature studies and COPERT model. The most effective method was found as EURO 3 standard causes 85% reduction in PM10 emissions. In the case of only EURO 3, EURO 4, EUR0 5 and EURO 6 vehicles can enter the zone, hourly PM concentration differences between base situation and low emission case has reached up 35μg/m3. Overall, a low emission zone will be announced on the Historical Peninsula, will provide a significant improvement in regional air quality.İstanbul, Türkiye'deki en büyük şehir olmasının yanı sıra 14 milyonu aşan nüfusuyla dünyadaki mega şehirlerden biridir. Bu şehir, artan nüfusu ve gelişen endüstrisi sebebiyle sıklıkla hava kirliliği problemi yaşamaktadır. Hava kirliliğinin, insan sağlığı üzerindeki etkileri literatürdeki bir çok çalışma tarafından kanıtlanmıştır. Kirleticilere maruz kalmanın, akciğer ve solunum yolu rahatsızlıkları, kardiyovasküler hastalıklar, astım şikayetlerinde artış, erken doğum ve ölüme varan sonuçları görülmektedir. Ulaşım kaynaklı emisyonlar, toplumun yoğunyaşadığı şehirleşmiş bölgelerde yoğunlaştığı için insan sağlığı açısından diğer emisyon kaynaklarına göre daha önemli bir yere sahiptir. Ayrıca bu emisyonların yer seviyesinde salınıyor olması da hava kirliliğine maruziyeti arttıran sebeplerden biridir. Bu tez çalışmasında trafik kaynaklı emisyonları sınırlandırmak ve azaltmak için alınacak önlemleri belirlemek ve etkilerini hesaplayabilmek için WRF meteroloji modeli, COPERT trafik kaynaklı emisyon hesaplama modeli ve CMAQ kimyasal taşınım modeli kullanılmıştır. Literatürdeki emisyon azaltım yöntemleri bu çalışmada teknolojik, davranışsal ve yönetimsel olarak gruplandırılmıştır. Bu önlemler arasında dizel partikül filtre kullanımı, EURO standartlarına göre araç girişlerinin sınırlandırılması, elektrikli otobüslerle toplu ulaşımın sağlanması, düşük emisyon bölgesi içindeki park ücretlerinin arttırılması, bölgeye giriş yapacak araçların trafik sıkışıklığı ücreti ödeyerek bölgeye giriş yapması, sinyalizasyonda yapılacak iyileştirmeler ve geliştirilmiş toplu ulaşım sistemleri sayesinde özel otomobil kullanımının azaltılması bulunmaktadır. Düşük Emisyon Bölgesi çalışması bu önlemlerin tek başına ya da topluca uygulanabildiği bir yöntemdir. Dünyada uygulama alanı gittikçe genişleyen bu metod 8 ülke ve 70 şehirde kurulmuş durumdadır. Bu tez çalışmasında İstanbul için aday bölgeler belirlenerek Düşük Emisyon Bölgesi çalışması ilk defa modellenmiştir. Meteoroloji ve kimyasal taşınım modelleri, 3 domain için koşturulmuştur. Ana domain tüm Avrupa'yı, Kuzey Afrika'yı ve Doğu Asya'nın bir kısmını, ikinci domain tüm Türkiye'yi, üçüncü domain İstanbul'u kapsamaktadır ve çözünürlükleri sırasıyla 30 km, 10 km, ve 2 km'dir. 30 km ve 10 km'lik domainlerde TNO'nun hazırlamış olduğuemisyon envanteri kullanılmıştır. Im'in İstanbul için hazırlamış olduğu emisyon envanteri 2 km mekansal çözünürlükte ve saatlik olarak başlıca antropojenik kaynakları içermektedir. Bu kaynakların içerisinde evsel ısınma, endüstri, atık yönetimi, solvent kullanımı, enerji üretimi, yakıt işleme ve ulaşım yer almaktadır. Bu çalışmada, COPERT modeli ile trafik kaynaklı emisyonlar hesaplanarak İstanbul'a ait envanterin ulaşım sektörü kısmında kullanılmıştır. Biyojenik emisyonlar için MEGAN modeli kullanarak doğal emisyonlar da hesaba katılmıştır. Emisyonların dağılımına bakıldığında ulaşım sektörü CO, NMVOC ve NOx kirleticilerinin ana kaynağı olarak görülmektedir. Endüstri ise SO2 emisyonlarının, çözücü kullanımı ve trafik ise NMVOC emisyonlarının ana kaynağıdır. İstanbul envanterindeki trafik sektörü, insan sağlığı açısından en önemli kirleticilerden biri olan PM için ana kaynak iken, COPERT'e ait emisyonların ulaşım sektörü için kullanılması durumunda PM için ana kaynak, üretim endüstrisi olmaktadır. İstanbul'da 26 adet hava kalitesi ölçüm istasyonu bulunmaktadır. Bu istasyonların hepsinde SO2 ve PM10 ölçümü yapılmakta olup bazılarındaysa bunlara ek olarak sıcaklık, rüzgar, azotoksit (NO, NO2, NOx), CO ve O3 ölçümleri yapılmaktadır. Bu çalışma esnasında bu istasyonlardan elde edilen konsantrasyon değerleriyle model sonuçları karşılaştırılmıştır. WRF modeli, 2-12 Kasım 2010 tarihleri arasında koşturulmuştur. Modelin sonuçları Atatürk Havaalanı ve Göztepe'deki hava kalitesi istasyonlarından elde edilen ölçüm sonuçlarıyla karşılaştırılmıştır. Zaman serisi ve istatistiksel analizler, WRF'un yüzey sıcaklığını yakalamada başarılı olduğunu göstermektedir. Modelin performansını arttırmak için modelin fiziksel parametreleri üzerinde değişiklikler yapılarak en uygun seçenek belirlenebilir. CMAQ modelinin çıktılarına göre hesaplanan saatlik PM10 konsantrasyonları, Aksaray hava kalitesi istasyonundan elde edilen PM10 ölçüm sonuçları ile tüm domainler için karşılaştırılmıştır. 30 km ve 10 km'lik domainler, 2 km'lik domaine göre model performansı açısından daha başarılıdır. İstanbul simülasyonu için, modelin ölçüm sonuçlarına göre daha yüksek konsantrasyonlar sergilediği görülmüştür. İstatistiksel analizler yapıldığında ölçüm sonuçları ve simüle edilmiş sonuçlar arasında düşük bir korelasyon görülmüştür. Bu zayıf performansın sebebi saatlik ölçümlerin karşılaştırılması, tek bir noktaya ait ölçüm sonuçlarının baz alınması, meteorolojik modeldeki ve COPERT modelindeki belirsizlikler, çalışma alanına uygun olmayan model sınır koşulları, zamansal profillerin uygun olmaması ve ölçüm hataları olabilir. Trafik kaynaklı hava kirliliğini azaltmak için uygun olan bölge ve yöntemler belirlenmiştir. Bölgeler belirlenirken yüksek gündüz nüfusuna sahip olmaları ve iş yerleri açısından merkez niteliğinde olmaları göz önünde bulundurulmuştur. Aday bölgeler Kadıköy, Maslak ve Tarihi Yarımada olarak seçilmiştir. Bu bölgeler trafik çekme özellikleriyle de düşük emisyon bölgesi uygulaması açısından uygundurlar. Trafik kaynaklı emisyonların 30% azaltılarak DUMAN emisyon işleme modeline verilmesi sonucunda, Tarihi Yarımada'da saatlik PM10 konsantrasyonlarında 10μg/m3 'a varan düşüş görülmüştür. Kadıköy bölgesi için maksimum fark 7μg/m3, Maslak bölgesi için maksimum fark 3μg/m3 olarak simule edilmiştir. Hem gündüz nüfusunun en fazla olduğu hem de emisyonlardaki azaltıma konsantrasyon değişimi olarak en çok yanıt veren bölge Tarihi Yarımadadır. Düşük Emisyon Bölgesi için seçilen Tarihi Yarımada'da uygulanacak yöntemlerin her birisi için PM10 emisyonlarında ne kadar düşüşe neden olduğu literatürdeki çalışmalar ve COPERT modelinin çıktıları kullanılarak hesaplanmıştır. Belirlenen metodların arasında, bölgeye sadece EURO 3 ve üzeri araçların girişine izin verilmesi uygulaması PM10 emisyonlarında 85% azaltım sağlamaktadır. Emisyondaki bu azaltım, referans durum ile Düşük Emisyon Bölgesi ilan edilen durum arasında saatlik bazda 35μg/m3 ' e varan farka sebep olmaktadır. PM için günlük ortalamalarda fark 15μg/m3' e varmaktadır. Bu önemli farkın sebebi EURO 3 standardından düşük olan araçların hem sayıca fazla olması hem de diğer yeni araçlara göre daha fazla kirletici yaymalarıdır. Bölgeye yalnızca yeni teknolojili ve az sayıda araç girişine izin verildiği takdirde hava kalitesinde önemli ölçüde iyileşmeler görülecektir. Bu çalışma, İstanbul'u daha fazla temsil eden sınır koşulları kullanılarak ve daha ayrıntılı emisyon envanteri hazırlanarak geliştirilebilir. Şu anda devam etmekte olan Ulusal Hava Kirliliği Emisyon Yönetim Sisteminin Geliştirilmesi projesi (KAMAG) ve COPERT'in araç dağılımı ve özellikleri kısımlarının güncellenmesi sayesinde model performansı yükseltilebilir.M.Sc.Yüksek Lisan