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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.

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.

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.

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.