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Smart farming (SF) has emerged as a scientific approach exploiting technology advances for the management of agricultural practices, focusing on the control of resources and chemicals used. There is still limited evidence in the scientific literature in regard to the efficiency of SF, particularly for targeted environmental issues, such as air pollutant emissions from agricultural activities. The present paper expoits quantitative data collected from questionnaires to farmers of 6 pilot areas in Greece, participating in the LIFE GAIA Sense project. Emissions and pollutant levels were calculated for two consecutive years in these pilot areas, namely 2019 (baseline year) and 2020, which is the first SF application year. The methodology for calculating realistic emissions data, following a combined tier 1/tier2 approach is presented. To this purpose, detailed activity data of the specific SF application areas related to agricultural activities were acquired, based on the responses of participating farmers to targeted questionnaires. Calculated emissions were used as input data for air quality modeling simulations to examine the efficiency of SF in reducing local pollutant concentrations. The results show significant emissions and concentrations reductions in five out of the six pilot areas, for all pollutants and greenhouse gases studied, due to the decrease in fuel consumption and N fertilizer applied, as a result of the farmers following the SF advice. Particularly for NH3, which is an agricultural air pollutant of concern due to its health and environmental impacts, emission reductions of around 30% (and by up to almost 60%) were calculated.

There is much debate around promoting waste to energy incineration facilities in many communities globally, mainly because of social opposition against potential negative health effects of the operation of these installations close to urban areas. In this paper, a novel decision support approach is developed and its applicability is demonstrated for the greater Thessaloniki area, Greece. In this area, the incineration facilities are hotly debated, mainly due to the "Not In My Back Yard" syndrome related with health considerations. The exclusive method of treatment is landfilling. Health impacts and corresponding externalities attributed to the operation of an incineration facility are reliably estimated. Three potential alternative sites and three scenarios of emission rates are considered, depending on the abatement technology used. The estimated externalities are compared to the corresponding ones attributed to other pressures in the area. The "Years of Life Lost (YOLL)" indicator attributed to the operation of the facility is 2.8 YOLL in the worst-case scenario. This corresponds to a minimal added implication in comparison with the 11,044 YOLL estimated for the area due to the other environmental pressures (road traffic, space heating, industrial activity). The externalities ratio (externalities due to incineration facility/total externalities) for the region is approximately 0.03%. Thus, the impact of this operation on human health is negligible -and preferable to landfilling- even in the case that maximum emission rates are considered. Efforts should be targeted towards enhancing public awareness and militating the widely acknowledged "Not In My Back Yard" syndrome by local communities.

This review provides a community’s perspective on air quality research focussing mainly on developments over the past decade. The article provides perspectives on current and future challenges as well as research needs for selected key topics. While this paper is not an exhaustive review of all research areas in the field of air quality, we have selected key topics that we feel are important from air quality research and policy perspectives. After providing a short historical overview, this review focuses on improvements in characterising sources and emissions of air pollution, new air quality observations and instrumentation, advances in air quality prediction and forecasting, understanding interactions of air quality with meteorology and climate, exposure and health assessment, and air quality management and policy. In conducting the review, specific objectives were (i) to address current developments that push the boundaries of air quality research forward, (ii) to highlight the emerging prominent gaps of knowledge in air quality research and (iii) and to make recommendations to guide the direction for future research within the wider community. This review also identifies areas of particular importance for air quality policy. The original concept of this review was borne at the International Conference on Air Quality 2020 (held online due to the COVID 19 restrictions during 18–26 May 2020), but the article incorporates a wider landscape of research literature within the field of air quality science. On air pollution emissions the review highlights, in particular, the need to reduce uncertainties in emissions from diffuse sources, particulate matter chemical components, shipping emissions and the importance of considering both indoor and outdoor sources. There is a growing need to have integrated air pollution and related observations from both ground based and remote sensing instruments, including especially those on satellites. The research should also capitalize on the growing area of lower cost sensors, while ensuring a quality of the measurements which are regulated by guidelines. Connecting various physical scales in air quality modelling is still a continual issue, with cities being affected by air pollution gradients at local scales and by long range transport. At the same time, one should allow for the impacts from climate change on a longer timescale. Earth system modelling offers considerable potential by providing a consistent framework for treating scales and processes, especially where there are significant feedbacks, such as those related to aerosols, chemistry and meteorology. Assessment of exposure to air pollution should consider both the impacts of indoor and outdoor emissions, as well as apply more sophisticated, dynamic modelling approaches. With particulate matter being one of the most important pollutants for health, research is indicating the urgent need to understand, in particular, the role of particle number and chemical components in terms of health impact, which in turn requires improved emission inventories and models for predicting high resolution distributions of these metrics over cities. The review also examines, how air pollution management needs to adapt to the above-mentioned new challenges and briefly considers the implications from the COVID-19 pandemic for air quality. Finally, we provide recommendations for air quality research and support for policy.

This document aims to impact the realization of the current project by recording all the necessary and available data for the thematic layers of land use and the surface parameters for the pilot areas that will be used as input data and surface boundary conditions for the numerical simulation that will be performed in WP3.

The dominant influence of shipping emissions on air quality of port cities and their surrounding urban areas has been demonstrated in a number of case studies, based on both assessment of monitoring data and the application of modelling tools. In the present work, chemical dispersion calculations are used for assessing the impact of marine traffic on air quality of Piraeus, Greece, and the neighbouring areas of the Athens urban agglomeration. A comprehensive marine emissions inventory is compiled using a bottom-up methodology on the basis of AIS traffic data, as well as activity and source parameter data obtained from other national databases, covering both merchant and passenger traffic in the area. A set of dispersion calculations are performed using the MEMO/MARS-aero chemical dispersion model for the Attica region, revealing the dominating contribution of the port area on the pollutant levels over the southern part of the city of Piraeus. Assessment of a hypothetical scenario, involving the implementation of cold ironing for ships at berth, indicates that emissions in the hoteling phase are significantly reduced, resulting to a notable reduction of concentrations in the port and the surrounding areas.

Interactions between different spatial and temporal scales play a major role in determining the flow structure over the urban canopy in densely built agglomerations. Aiming to address the limitations which arise as a result of the physical disparities between the different modelling scales, a two-way scheme has been introduced for coupling the mesoscale model MEMO and the microscale model MIMO, utilising a collection of interpolating metamodels. The coupled system was used to simulate meteorological fields over the Greater Paris area during a multi-day wintertime case study. Its performance as a meteorological driver model was further evaluated by introducing the calculated meteorological fields as driving input in air quality calculations performed using the Eulerian chemical dispersion model MARS-aero.

The need for comprehensive prognostic meteorological models is paramount in various applications related to environmental assessment. The inclusion of urban land cover in the computational domain in mesoscale models introduces new challenges for accurately incorporating the complex interactions related to the dynamical and thermal effects of the urban canopy. Aiming to address these requirements, a new urban surface scheme was introduced in a mesoscale meteorological model incorporating parameterisations of the area-averaged effects of drag and turbulence production as well as an improved representation of the surface heat and moisture fluxes. In addition, an advanced data assimilation module was implemented for enabling the self-consistent estimation of anthropogenic heat fluxes on the basis of representative satellite data, as well as the introduction of resulting forcing in the surface energy budget. The enhanced version of the model was evaluated in two mesoscale applications covering the greater urban areas of Paris, France and Athens, Greece. The model was evaluated over the course of three periods of strong anticyclonic conditions, enabling a better assessment of the influence of urban effects. The results confirmed that the urban surface module enhancements led to a significant improvement of model performance. Finally, the assimilation of anthropogenic heat data in the model provided an improved capability of reproducing the observed spatial and temporal variation of surface temperature.

Anthropogenic effects in urban areas influence the thermal conditions in the environment and cause an increase of the atmospheric temperature. The cities are sources of heat and pollution, affecting the thermal structure of the atmosphere above them which results to the urban heat island effect. In order to analyze the urban heat island mechanism, it is important to estimate the anthropogenic heat flux which has a considerable impact on the urban energy budget. The anthropogenic heat flux is the result of man-made activities (i.e. traffic, industrial processes, heating/cooling) and thermal releases from the human body. Many studies have underlined the importance of the Anthropogenic Heat Flux to the calculation of the urban energy budget and subsequently, the estimation of mesoscale meteorological fields over urban areas. Therefore, spatially disaggregated anthropogenic heat flux data, at local and city scales, are of major importance for mesoscale meteorological models. The main objectives of the present work are to improve the quality of such data used as input for mesoscale meteorological models simulations and to enhance the application potential of GIS and remote sensing in the fields of climatology and meteorology. For this reason, the Urban Energy Budget concept is proposed as the foundation for an accurate determination of the anthropogenic heat discharge as a residual term in the surface energy balance. The methodology is applied to the cities of Athens and Paris using the Landsat ETM+ remote sensing data. The results will help to improve our knowledge on Anthropogenic Heat Flux, while the potential for further improvement of the methodology is also discussed.

Online coupled mesoscale meteorology atmospheric chemistry models have undergone a rapid evolution in recent years. Although mainly developed by the air quality modelling community, these models are also of interest for numerical weather prediction and regional climate modelling as they can consider not only the effects of meteorology on air quality, but also the potentially important effects of atmospheric composition on weather. Two ways of online coupling can be distinguished: online integrated and online access coupling. Online integrated models simulate meteorology and chemistry over the same grid in one model using one main time step for integration. Online access models use independent meteorology and chemistry modules that might even have different grids, but exchange meteorology and chemistry data on a regular and frequent basis. This article offers a comprehensive review of the current research status of online coupled meteorology and atmospheric chemistry modelling within Europe. Eighteen regional online coupled models developed or being used in Europe are described and compared. Topics discussed include a survey of processes relevant to the interactions between atmospheric physics, dynamics and composition; a brief overview of existing online mesoscale models and European model developments; an analysis on how feedback processes are treated in these models; numerical issues associated with coupled models; and several case studies and model performance evaluation methods. Finally, this article highlights selected scientific issues and emerging challenges that require proper consideration to improve the reliability and usability of these models for the three scientific communities: air quality, numerical meteorology modelling (including weather prediction) and climate modelling. This review will be of particular interest to model developers and users in all three fields as it presents a synthesis of scientific progress and provides recommendations for future research directions and priorities in the development, application and evaluation of online coupled models. This work was realised within and supported by the COST Action ES1004 EuMetChem. Several authors of this article are grateful for the support received from the following projects: EC FP7 TRANSPHORM and PEGASOS, Nordic EnsCLIM, the RF SOL No 11.G34.31.0078 and No 14.B37.21.0880 at RSHU, the US NSF EaSM program (AGS-1049200) at NCSU, the German Science Foundation grant No SCHL-499-4, the Spanish projects “Supercomputación y eCiencia” (CSD2007-0050) and CGL2010-19652, Estonian grants ETAG 7895 and SF0180038s08, and the NASA’s Air Quality Science Team (AQAST) programme. Acknowledgements go to Ralf Wolke (IfT Leipzig, COSMOMUSCAT); Kristian Nielsen, Ashraf Zakey and Roman Nuterman (DMI, Enviro-HIRLAM), Jacek Kaminski, Joanna Struzewska (GEM-AQ); Fabien Solmon (ICTP, RegCM), Maud Leriche, Christine Lac (Meso-NH), Malte Uphoff (Univ. Hamburg, M-SYS), Erik van Meijgaard (KNMI, RACMO2), Claas Teichmann (CSC, REMO-HAM), Bärbel Langmann (Univ. Hamburg, REMOTE), Rohit Mathur, Jon Pleim, Christian Hogrefe (US EPA, WRFCMAQ) for providing detailed information on the named model systems and for valuable comments, Carlos Pérez García-Pando for permission of his figure use, Sabine Ehrenreich for a technical support with the manuscript revision, and all COST ES1004 members for collaboration and productive discussions during COST meetings. The editor David Topping, as well as David Schultz, Jaakko Kukkonen, Mark Z. Jacobson, Shaocai Yu, Peter Builtjes, Rahul Zaveri, Carsten A. Skjoth, Paul A. Makar and 3 anonymous reviewers are thanked for thorough reviews, and for many valuable comments that substantially improved this article.

An Air Quality Management System (AQMS) has been developed and installed in the Department of Labour Inspection of the Republic of Cyprus in order to meet the requirements of the European Air Quality Directive (2008/50/EC). Following an operational evaluation of the system’s performance, several improvements of its core and interface modules have recently taken place. In an effort to optimize the core model performance, a revised methodology for determining boundary conditions (BC) has been implemented. This new BC module enables the transfer, formatting and, finally, the assimilation of concentration data originating from the ensemble forecasts of the regional scale models of the MACC Project. As a further improvement, an empirical approach for the improved estimation of a street-scale concentration increment on top of the urban background has been developed, addressing the inherent shortcoming of mesoscale models in predicting air pollution levels in traffic hotspots. The methodology incorporates a functional relationship between local meteorological parameters, street characteristics and traffic emissions, calibrated on the basis of calculated increments in representative locations. Finally, a range of additional features have been incorporated in the AQMS functionality, including a versatile reanalysis module, as well as a user interface for the analysis of weighted back trajectories.

The importance of different processes and feedbacks in online coupled chemistry-meteorology models for air quality simulations and weather prediction was investigated in COST Action ES1004 (EuMetChem). Case studies for Europe were performed with different models as a coordinated exercise for two episodes in 2010 in order to analyse the aerosol direct and indirect radiative effect and the response of different models to aerosol-radiation interactions.

In street scale numerical simulations utilising computational fluid dynamics (CFD) models, normally the inlet flow should preserve the horizontal homogeneity upstream and downstream of the area where the resolved obstacles reside. Hence, the vertical profiles of the main atmospheric flow quantities must comply with the roughness characteristics of the ground surface. Horizontally homogenous boundary conditions do not normally agree with field measurements while at the same time the profiles obtained by measurements do not preserve the homogeneity of the flow. As a result, in recent years alternative sets of boundary conditions have been proposed in order to bridge the gap between real life vertical profiles of the atmospheric boundary layer and those applied as input boundary conditions for modelling purposes. In the present study, the homogeneity of the boundary conditions is addressed by applying the power law for the mean wind speed to obtain the appropriate vertical profiles.

The operation of large open-pit lignite mines represents a significant source of fugitive dust emissions connected to energy production. Emission inventories can be used to provide operational estimates of the total dust burden in the surrounding areas attributable to mining operations. In this work, a methodology based on the inverse dispersion modelling approach, combining two different dispersion models, is used for preparing a dust emissions inventory for several activity types in the lignite mines of Western Macedonia, Greece. A three-year campaign of field measurement experiments provides the necessary meteorological data and upwind-downwind concentration levels in the area of each activity. A comparison of calculated emission rates provided by the two dispersion models indicates a very good agreement, while the normalised downwind concentration timeseries are accurately reproduced. Emission factors are calculated for each experiment and per-activity, leading to the formulation of empirical relations for the total fugitive dust emissions.

Interactions between different spatial and temporal scales play a major role in determining the flow structure over the urban canopy in densely built agglomerations. The intense surface in-homogeneities result in the generation of additional terms in the turbulent transport within the urban atmospheric boundary layer (ABL), which in effect generate equally intense temporal in-homogeneities. Aiming to address the limitations which arise as a result of physical disparities between the scales involved, a novel two-way scheme has been developed within the frame of the EU MEGAPOLI project to couple the mesoscale model MEMO and the microscale model MIMO, utilising a collection of interpolating metamodels. The methodology developed was employed for assessing the effects of multiscale interactions on turbulent transport in the city of Paris using the MARS-aero model, and was validated based on comparisons with monitoring measurements. Simulation results reveal an improvement of the prediction skill over non-coupled models in accurately resolving scale interactions on the atmospheric flow within the urban ABL.

We investigate the electronic and optical properties of free-standing and epitaxially strained ${\mathrm{Si}}_{1\ensuremath{-}y}{\mathrm{C}}_{y}$ alloys. We first determine the microscopic atomic structure of the alloys using the semi-grand-canonical Monte Carlo method and empirical interatomic potentials. For the calculation of the electronic and optical properties of the alloys we employ a supercell geometry and an empirical tight-binding model, which was fitted to reproduce the relevant band structures obtained from first-principles calculations. Our approach allows for a thorough investigation of C alloying and strain effects on the band gap, the band offsets, the effective masses of the upper valence and lowest conduction bands, and the optical properties. Our results are in very good agreement with experiment.

We study the electronic and optical properties of cubic (3C) SiC, using a combination of first-principles and tight-binding electronic structure calculations. We employ pseudopotential density functional theory calculations, with appropriate corrections to the energy of conduction bands, to investigate the band structure of this material and obtain band gaps that are in agreement with experimental results. The optical properties are then studied within the framework of the empirical tight-binding model, which is fitted to reproduce the first-principles calculations. This approach allows for a thorough investigation of the dielectric functions, the reflectivity, and the refractive index. Critical points are identified and connected to the appropriate transitions in the band structure. The results are in good agreement with available experimental data. In addition, we investigate spin splitting effects.

An empirical tight-binding model with an orthogonal sp 3 set of orbitals, interactions up to second neighbor and spin-orbit coupling, is used to describe the electronic and optical properties of bulk as well as strained GaAs and InP. The band structure and the dielectric functions of bulk GaAs and InP are calculated and found to be in good agreement with experimental results. The deformation potentials for the E 1 and E 1 + Δ 1 transitions, for uniaxial strain along the [001] and [111] directions, are evaluated. Also the piezooptical tensor components P 11 , P 12 , P 44 , as well as the differential reflectivity were calculated. Finally the refractive index as a function of energy is calculated for hydrostatic pressures in the range of 0 to 8 GPa. The theoretically obtained results are in good agreement with existing experimental data.

The deformation potentials and the piezooptical properties of Si, for strain along the [001] and [111] directions, are investigated with the use of a realistic empirical tight-binding model. The values, as well as their sign, of the deformation potential constants D 1 1 , D 1 5 , D 3 3 , and D 3 5 for the variation of the critical energy E 1 are evaluated for uniaxial and biaxial strain. The sign is found to be negative for D 1 1 , D 3 3 , and D 3 5 , and positive for D 1 5 . The dielectric function of Si under pressure, as well as the reflectivity and the linear piezooptical tensor components P 11 (ω), P 12 (ω) and P 44 (ω) are also evaluated. The main structures in P ij are located around the critical points E 1 and E 2 .

The piezo-optical properties of Ge, for pressure along the [001] and [111] directions, are calculated with the use of a realistic empirical tight-binding model. The real and imaginary part of components ${P}_{11}(\ensuremath{\omega})$, ${P}_{12}(\ensuremath{\omega})$, and ${P}_{44}(\ensuremath{\omega})$ of the linear piezo-optical tensor for Ge are evaluated. The main structures in ${P}_{\mathrm{ij}}$ are located around the ${E}_{1}$ and ${E}_{2}$ critical points. Deformation potential constants ${D}_{1}^{1}$, ${D}_{1}^{5}$, ${D}_{3}^{3}$, and ${D}_{3}^{5}$, for the ${E}_{1}\ensuremath{-}{(E}_{1}+{\ensuremath{\Delta}}_{1})$ transitions are also evaluated. The theoretically obtained results are in good agreement with existing experimental values.

Estimation of parameters of the gravitational-wave signal from a coalescing binary by a network of laser interferometers is considered. A solution of the inverse problem for the network of three detectors is generalized to the network of N detectors. This enables, from measurements at individual detectors of the network, optimal estimation of the astrophysically interesting parameters of the binary system: its distance from Earth, its position in the sky, and the chirp mass of the system. Maximum likelihood and least-squares methods are used to obtain the solution. The existence of the solution in view of the nonlinear nature of the problem and the noise in the detectors is discussed. An alternative solution of the inverse problem that circumvents the singularities present in the problem is proposed. Accuracy of the estimation of the parameters is assessed from the inverse of the Fisher information matrix. The variance of the maximum likelihood estimator of the distance is calculated for a simple model and compared with the approximate one obtained from the Fisher matrix. Extensive Monte Carlo simulations are performed to assess the accuracy of the estimation of the astrophysical parameters by networks of three and four detectors. Addition of the fourth detector to the network markedly improves the performance of the network. Adding the fourth node in Australia to the LIGO/VIRGO network increases the number of detectable events roughly twofold. For the four-detector network one can find among all detectable events again roughly twice the number of events for which accurate determination of the binary distance is possible. Moreover, the position of the binary in the sky can be typically determined three to four times more accurately for the enhanced LIGO/VIRGO network.

The recent air quality directive (2008/50/EC) encourages the introduction of modelling as a necessary tool for air quality assessment and management. Towards this aim, an air quality management system (AQMS) has been developed and installed in the Department of Labour Inspection (DLI) of the Republic of Cyprus. The AQMS comprises of two operational modules, providing hourly nowcasting and daily forecasting of the air quality status, implemented as an integrated model system that performs nested grid meteorological and photochemical simulations. A third operational module provides the capability of an interactive configuration of custom emission scenarios and corresponding model runs covering user-defined domains of interest. Statistical indicators are calculated at the end of each day for the measurement locations of DLI's air quality monitoring network. Besides, the system provides an advanced user interface, which is realised as a web-based application providing access to model results from any computer with an internet connection and a web browser.

Matched filtering is proposed as a way to detect the gravitational-wave signal from a coalescing binary and to estimate its parameters. One of the authors (AK) has investigated the theoretical performance of this method by calculating the signal-to-noise ratio and the covariance matrix for the parameters of the signal. In this work we try to verify how the above method will work in practice. We generate a Gaussian, approximately white noise and add the signal, and then, using the algorithm derived from the maximum likelihood principle, we find the maximum likelihood estimators of the parameters. The procedure amounts essentially to the maximization of the correlation of the data with the filter matched to the signal. The size of the maximum of the correlation determines the probability of the detection of the signal. We repeat the procedure a thousand times to obtain suitable statistics for the estimators. We find that it agrees well with the theoretical predictions. We also investigate the post-Newtonian effects. It was recently shown by the Caltech group that the matched filtering technique is sensitive to the post-Newtonian corrections. We demonstrate this by inputing the signal with the first post-Newtonian term and correlating the data with the Newtonian filter. We find that we can still detect the post-Newtonian signal with a Newtonian filter but the maximum of the correlation falls by 40% and consequently the probability of the detection decreases. The estimates of the mass parameter of the post-Newtonian signal and its time-of-arrival are shifted by a certain amount from the true values. We also address the problem of the estimation of the individual masses of the binary.

Aerosols have a significant impact on the Earth’s radiation budget by scattering and absorbing solar radiation thus decreasing the radiation absorbed at the surface and increasing low-level static stability. Recent developments in urban air pollution modelling have focused on the introduction of two-way coupling between aerosol modules and the driving meteorological models, aiming to a more accurate description of aerosol-induced radiative forcings in the atmosphere. In this study, the feedback mechanism due to the aerosol direct effect is examined with the aid of a mesoscale Eulerian meteorological model and a chemical transport model, as part of an on-line coupled scheme. For the assessment of the performance of the coupled model system, pollutant dispersion over the Paris area is simulated over a summer period in 2005 identified in the framework of the MEGAPOLI project. A comparison between the standalone and coupled calculations reveals that the radiative forcing due to the direct effect has a substantial impact on the calculated meteorological fields and leads to an improved representation of the pollutant concentration patterns.

A simple approach for accurately estimating an urban concentration increment on top of the regional background for urban areas in Europe is presented. The method operates by establishing a functional relationship between the concentration increment and the local meteorological situation, the city characteristics, the urban emissions and the background concentrations. In the current study, the above method was applied for PM 10 and NO 2 . Pollutant concentrations needed for the multiple regression process can be derived both from measurements and high resolution urban scale model results. The results demonstrate the capability of this simple approach to reproduce the urban increment with satisfactory accuracy, thus providing a tool for fast but still reliable quantitative assessments of urban air quality that can subsequently be used in calculations of exposure and health impact assessment. Moreover, scenario calculations for the urban increments can be based on scenario emissions and respective modelled regional background concentrations.