1,081 research outputs found

    Online-coupled meteorology and chemistry models: history, current status, and outlook

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    The climate-chemistry-aerosol-cloud-radiation feedbacks are important processes occurring in the atmosphere. Accurately simulating those feedbacks requires fully-coupled meteorology, climate, and chemistry models and presents significant challenges in terms of both scientific understanding and computational demand. This paper reviews the history and current status of the development and application of online-coupled meteorology and chemistry models, with a focus on five representative models developed in the US including GATOR-GCMOM, WRF/Chem, CAM3, MIRAGE, and Caltech unified GCM. These models represent the current status and/or the state-of-the science treatments of online-coupled models worldwide. Their major model features, typical applications, and physical/chemical treatments are compared with a focus on model treatments of aerosol and cloud microphysics and aerosol-cloud interactions. Aerosol feedbacks to planetary boundary layer meteorology and aerosol indirect effects are illustrated with case studies for some of these models. Future research needs for model development, improvement, application, as well as major challenges for online-coupled models are discussed

    Acid deposition in Colorado: a potential or current problem; local versus long-distance transport into the state

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    August 13-15, 1986.Includes bibliographical references.A compendium of papers presented at a workshop sponsored by the Cooperative Institute for Research in the Atmosphere, Colorado State University in Fort Collins, Colorado on August 13-15, 1986

    Modelling of the transport of nitrogen and sulphur contaminants to the Baltic Sea region

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    In the work for this thesis, the 3D model Hilatar, which can be used to monitor and numerically forecast air pollution transport, chemical transformation and deposition in Europe and its sub-areas, has been developed. Model has been used to assess the sulphur and nitrogen concentrations and fluxes over the Baltic Sea and its surroundings in 1985, 1988 and 1993-2002 and to study their time variation caused by physical, meteorological and model structural factors, as well as other uncertainties connected to the 3D modelling. The model has been used e.g. in quantifying nitrogen flux to the Baltic Sea, and the factors that influence it, within the EU BASYS (Baltic Sea System Study) project and in studying of pollutants in episodic situations. The first model version has been used in calculating the Daiquiri-model unit matrixes for the Finnish Environmental Institute. The temporal- and spatial variation of the concentration and deposition of air pollutants is high. Episodicity is to a large extent caused by meteorological factors, the time variation of emissions, high concentration gradients close to source areas and long-range transport from high-intensity emission areas. Considering the Nordic countries, the modelled deposition of oxidised nitrogen in Lapland is around 10 % of that in Denmark, the ammonium deposition being still smaller. Although sulphur deposition is high in the vicinity of the large industrial areas of the Kola Peninsula, is does not exceed the Central European level there. The wet flux of nitrogen to the Baltic Sea is strongest in winter and autumn. The dry nitrogen deposition share was highest in Southern Sweden and Denmark in summer due to high ammonium emissions. The effects of the decreasing emission trend could not be seen in Northern European N-deposition in 1993-98; S-deposition decreased slightly, however. The prevailing meteorological conditions were the primary cause of the inter-annual variation of regional deposition. Annual deposition to the open Baltic Sea area (391 000 km2) over the period 1993-1998 vary in the range 140-180 kt(N) for NOx and 100-120 kt(N) for NHx. The relative importance of the atmospheric load for algae growth in the Baltic Sea needs to be further studied since the sea is already rather badly eutrophicated and the primary production is largely driven by the nutrients that have already accumulated in the system. Modelled NOx and SO2 concentrations are at their highest during winter, due to slower chemical and terrestrial deposition sinks, maximum emissions and more frequent inversions. Ammonia emissions are highest during the summer and the conversion of NH3 to ammonium-sulphate particles is stronger in winter when there is more sulphate in the air. HNO3 levels are low in winter due to low reactivity, short days and reactions with NH3. The critical deposition limits were exceeded, but the critical wintertime SO2 and annual NO2 concentrations were not exceeded in the Nordic background areas, although this occurred for SO2 over large areas in Europe especially in the cold winter of 1996. Comparison with field campaign results and long-term measurements demonstrated a rather good description of both the spatial and temporal characteristics of the S and N pollution in the Baltic Sea region. Model results and meteorological input data are stored in two continuously updated databases. They can be used in studying simultaneous effect of meteorological and air pollution stresses on vegetation.reviewe

    Research report 1987-1989: Environmental Quality Laboratory and Environmental Engineering Science, W. M. Keck Laboratories

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    This research biennial report for 1987-89 covers the activities of both the Environmental Engineering Science program and the Environmental Quality Laboratory for the period October 1987-November 1989. Environmental Engineering Science is the degree-granting academic program housed in the Keck Laboratories, with associated research projects. The Environmental Quality Laboratory is a research center focusing on large scale problems of environmental quality and natural resources. All the faculty and students involved in EQL projects are part of one of the regular academic programs, with the largest number being in Environmental Engineering Science. Hence the convenience of this combined report. In the lists of students, degrees, and research projects we have included some students in other degree programs who are working on environmental topics under one of the professors associated with EES and/or EQL. Caltech's small size and flexible structure allows professors to participate in more than one academic program including the supervision of doctoral students. The report starts with brief descriptions of EQL and EES, then lists the people - professors, research staff, visitors and consultants, support staff, and graduate students. Next is a listing of our research sponsors and donors, to whom we are all indebted for making these programs possible. The main part of the report presents the research summaries for all our activities including publications during the period October 1987 - November 1989. Also included at the end of the report is a listing of books published during 1987-89 (which do not appear in the research summaries) and information about a major smog conference held in 1988. It is hoped this report will be a useful reference not only for prospective students and visitors but also for the entire EES and EQL group

    Numerical Air Quality Forecast over Eastern China: Development, Uncertainty and Future

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    Air pollution is severely focused due to its distinct effect on climate change and adverse effect on human health, ecological system, etc. Eastern China is one of the most polluted areas in the world and many actions were taken to reduce air pollution. Numerical forecast of air quality was proved to be one of the effective ways to help to deal with air pollution. This chapter will present the development, uncertainty and thinking about the future of the numerical air quality forecast emphasized in eastern China region. Brief history of numerical air quality modeling including that of Shanghai Meteorological Service (SMS) was reviewed. The operational regional atmospheric environmental modeling system for eastern China (RAEMS) and its performance on forecasting the major air pollutants over eastern China region was introduced. Uncertainty was analyzed meanwhile challenges and actions to be done in the future were suggested to provide better service of numerical air quality forecast

    The effect of short-term changes in air pollution on respiratory and cardiovascular morbidity in Nicosia, Cyprus.

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    Presented at the 6th International Conference on Urban Air Quality, Limassol, March, 2007. Short-paper was submitted for peer-review and appears in proceedings of the conference.This study investigates the effect of daily changes in levels of PM10 on the daily volume of respiratory and cardiovascular admissions in Nicosia, Cyprus during 1995-2004. After controlling for long- (year and month) and short-term (day of the week) patterns as well as the effect of weather in Generalized Additive Poisson models, some positive associations were observed with all-cause and cause-specific admissions. Risk of hospitalization increased stepwise across quartiles of days with increasing levels of PM10 by 1.3% (-0.3, 2.8), 4.9% (3.3, 6.6), 5.6% (3.9, 7.3) as compared to days with the lowest concentrations. For every 10μg/m3 increase in daily average PM10 concentration, there was a 1.2% (-0.1%, 2.4%) increase in cardiovascular admissions. With respects to respiratory admissions, an effect was observed only in the warm season with a 1.8% (-0.22, 3.85) increase in admissions per 10μg/m3 increase in PM10. The effect on respiratory admissions seemed to be much stronger in women and, surprisingly, restricted to people of adult age

    Quantification of short-term erosion rates using the cosmogenic radionuclide Be-7

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    ABSTRACT The fallout radionuclides 137Cs, 210Pbex are used widely for obtaining quantitative information on soil erosion and sediment redistribution rates within agricultural landscapes, over several spatial and temporal scales, and they are frequently seen to represent a valuable complement to conventional soil erosion measurement techniques. However, measurements of these radionuclides provide estimates of medium term (i.e. 40-100 years) soil erosion rates. The shorter-term perspective provided by the 7Be method has the potential to estimate soil erosion rates associated with individual events or short periods. The 7Be method has become increasingly relevant in an environment impacted by climate change, changing land use and other human activities. The present work establishes a mathematical model based on the physical processes of molecular diffusion and radioactive decay, to study the vertical behaviour of 7Be in soils. This model was further used to quantify erosion rates for 12 individual erosional events over a period of two years at our study site in Müncheberg, Germany. The scope of the model was explored analytically as well as numerically for Pulse-like fallout initial condition, zero concentration initial condition and exponential distribution initial condition. The model was fitted to more than 15 depth distributions and the resulting model parameter, effective diffusion coefficient D, is evaluated. In general diffusion coefficients estimated were of the order of 10-12 10-13 m2 s-1 for loamy to sandy soil types. Diffusion coefficients estimated for our study site were about 10-13 m2 s-1. The soil analyses indicate that the diffusion coefficient D is not merely a fitting parameter, but is related to the physico-chemical properties of radionuclide transport in soils. The erosion rates estimated at tilled and no-till plots at our study site were between < 0.001 - 4.7 ± 0.4 kg m-2 and 0.3 ± 0.5 kg m-2 - 2.0 ± 1.4 kg m-2 respectively. The magnitude of erosion rates estimated at the no-till plots was less than that at the tilled plots. The main conclusions of this work are: - The mathematical model developed during this study describes the transport of 7Be in soils. It is the first extensive model proposed so far that despite of its many simplifications, adequately represents the exponential distribution of 7Be profiles at disturbed and undisturbed or reference sites. - Main physical processes, which transport of 7Be in soil are, diffusion and radioactive decay. Migration parameters and measurements confirm that sorption is the main physical process, which confines 7Be concentration to soil surface. - Current erosion estimation methods with 7Be available in the literature for estimating erosion rates for single rainfall event was successfully modified to quantify erosion rates for multiple rainfall events. - Erosion rates estimated with 7Be technique were successfully used to differentiate between the rill-interrill, splash and surface erosion at the study plot. - The Diffusion model proposed in this study does not take into account the vegetation cover and thus overestimates the erosion rates or in some cases shows the occurrence of deposition on the plot

    Development and application of a comprehensive methodology for the analysis of global and local emissions of energy systems

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    The energy sector is a source of economic and social progress, but it is also the main responsible of air pollution resulting from human activity, mainly from the combustion of fossil fuels and bioenergy. The impacts on atmosphere may be divided into global effects, due to change in concentration of greenhouse gases, and regional/local effects, due to the dispersion of SO2, NOx, particulates and other gases. The aim of this thesis is the development and application of a methodology for calculating the emissions in atmosphere associated with energy management interventions. The methodology aims to characterize and quantify the environmental impacts affecting both the local and global scale. The pollutants involving local effects considered in this study are nitrogen oxides and particulate matter. Globally, the emission of greenhouse gases is considered, by quantifying the equivalent CO2 (CO2eq) emitted. The environmental impact of an energy option is quantified in terms of its emission balance, i.e. by comparing the present situation with one (or more) future scenarios. The study at the local scale also considers the dispersion of pollutants using modelling tools. The methodology is applied to two case studies located in the Italian Metropolitan City of Turin, characterized by different application contexts and different scales of operation. The first case study is represented by a system for the production and conversion of biogas and biomethane. The analysis of global emissions considers four different operating scenarios. The results show a CO2 reduction of 1426 t/y for biogas combustion in full cogeneration mode (generation of both heat and electricity). Biomethane for transports scenario provides a similar result (1379 t/y). If biogas combustion with partial cogeneration is considered (generation of electricity only), the CO2 balance approaches to zero. The evaluation of local impacts is made with two different dispersion models. The application of an Octave-based Gaussian model provides an average increase of concentration both for NOx and TSP, in the order of units of g/m3. The results of CALPUFF model simulations show a slight decrease of concentration in the order of 10-2 g/m3. The second case study consists of a potential extension of the district heating network in the urban area of Turin. The production of local emissions is calculated considering the operation of the main power plants in response to the estimated heat demand. Avoided emissions are calculated simulating the heat production of centralized residential heaters. The results of CALPUFF model simulations show a potential reduction of NOx average concentration between 1 and 6 g/m3. The results of global emissions show an unfavorable balance in the order of 104 t/y of CO2, that varies depending on the assumptions on the emission factors of the power units. A comprehensive final discussion is reported after the analysis of the two case studies. The calculation of two indicators (the “thermal benefit vs. local emission indicator” and the “local to global emission ratio”) is also included to discuss a possible standardization of the proposed methodology. This study provides important information on the effects on air quality resulting from the modification of the energetic management of an area or settlement. The employed methodology is consistent and comprehensive in identifying the potential optimal solutions for energy production and management, as well as identifying the consequences to a given scenario under an environmental point of view

    Ammonia cycling and emerging particulate matter pollutants under arable land-use management: A modelling approach

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    Air quality monitoring in Ireland is under the jurisdiction of the Environmental Protection Agency in compliance with the Gothenburg Protocol, EU/national legislation, and the National Clean Air Strategy. Particulate Matter (PM) has been acknowledged as a key atmospheric pollutant, with serious public health impacts and no safe threshold of exposure in place to-date. Ammonia (NH3) emissions are linked to the secondary production of PM through atmospheric reactions occurring with acidic atmospheric components such as sulfuric acid, nitric acid, and hydrochloric acid. These reactions result in the formation of ammonium sulfate, ammonium nitrate and ammonium chloride, among others. More than 95% of NH3 emissions occurring in Ireland arise from agriculture, with minor contributions from transport and natural sources. This study aims to advance knowledge and understanding of the role of arable agricultural practices and management in NH3 enrichment and aid in mapping of the sources of PM production. The nature and contribution of NH3 in the atmosphere to secondary PM in defined arable settings will be examined to provide greater insight into system dynamics facilitating emission control and mitigation measures to be implemented. This will be achieved through a review of existing literature and database assessment combined with the application of a localised field monitoring network in arable agricultural settings. As Ireland currently has no active atmospheric NH3 monitoring in place, reported emission levels can prove to be imprecise. And lead to over- and under-estimation of NH3 gas emissions to the atmosphere from sources such as agriculture. By establishing localized monitoring stations at emission sources, the precision of the estimated NH3 concentrations in the atmosphere can be improved. This can also lead to improved understanding of PM dynamics and formation. This will be achieved by using a combination of active and passive sampling instruments for in-field atmospheric sample collection, which will then be analysed in the laboratory using ion chromatography. Additionally, to gain a fuller understanding of the dynamics of an agricultural system, background monitoring of soil properties and water nutrient enrichment will also be carried out. The output of this project will build on existing theories of NH3, and PM dynamics established by previous research, and combine these with field data, including agricultural practices, NH3 source production and PM generation, soil and water enrichment and quality background monitoring to synthesise a new mechanistic paradigm. This new understanding will be operationalised through the development of a conceptual model of NH3 dynamics and PM generation, and agri-ecological interactions known as Conceptual Ammonia-aeroSol bIOspheric Simulation (CASIOS). The model builds on a Drivers, Pressures, State, Impacts, Responses framework, with an additional attribute introduced under the term ‘Concept’ which includes environmental conditions previously not considered under this paradigm
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