AIR QUALITY MODELLING IN THE CITY OF MYTILENE, GREECE

Gaussian plume dispersion models traditionally have been used for estimating the spatial distribution of air pollutants close to point sources. Modifications over the past decades have enabled these models to determine pollutant concentrations around line as well as area sources. AERMOD, an open source Gaussian plume model recommended by the US Environmental Protection Agency (EPA), is one of the most widely used model for regulatory purposes. In this work we employ AERMOD to investigate how the spatial distribution of PM10 in the city of Mytilene is affected by the activity at the port of the city and a nearby power plant that serves the needs of the whole island. The emissions by the ships approaching the port of Mytilene were calculated using the Tier 3 EMEP/EEA methodology. It is a bottom-up technique, based on the tracking of the movements of ships (cruising and maneuvering) or their dockside mooring (berthing) and the application of appropriate emission factors depending on the engine type, the fuel type and the different phase of the trip. The emissions by the power plant were calculated using Tier 1 EMEP/EEA methodology for public electricity and heat production which is based on the amount of energy production and emission factor per unit of energy. Predictions of the spatial distribution of PM10 emitted by the ships and the power plant were performed for the period between 10 and 20 of August 2012. The meteorological data required for the simulation were obtained from the Hellenic National Meteorological Service (HNMS) weather station of Mytilene International Airport (surface data) and European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis (upper air data). The emissions of the power plant exceeded a little the emissions by the port. Although the ships use less of the power of their engines inside the port (manoeuvring, at berth) compared to cruising, the emissions inside the port are higher because the ships remain more time there. AERMOD results revealed low concentration levels of PM10 originating from both port activity and PPC. The pollution is significantly influenced by the study region topography (hilly terrain) and the prevailing north winds.