Papers by Dimitrios Melas
EGU General Assembly Conference Abstracts, Apr 1, 2013
Atmospheric Environment, Dec 1, 2015
h i g h l i g h t s A new natural emissions model for Europe integrates well-documented methodolo... more h i g h l i g h t s A new natural emissions model for Europe integrates well-documented methodologies. Very good model performance in comparison with existing uncertainties. Windblown dust emissions are the highest in summertime in Southern Europe. Sea salt emissions are the highest in Atlantic Ocean in autumn. During summer sea salt emissions are the highest in Mediterranean Sea.
Atmosphere, 2021
The Mediterranean is recognized among the most responsive regions to climate change, with annual ... more The Mediterranean is recognized among the most responsive regions to climate change, with annual temperatures projected to increase by 1–5 °C until 2100. Large cities may experience an additional stress discomfort due to the Urban Heat Island (UHI) effect. In the present study, the WRF-ARW numerical weather prediction model was used to investigate the climate change impact on UHI for two Mediterranean cities, Rome and Thessaloniki. For this purpose, three 5-year time-slice simulations were conducted (2006–2010, 2046–2050, 2096–2100) under the Representative Concentration Pathway (RCP) 8.5 emission scenario, with a spatial resolution of 2 km. In order to comprehensively investigate the urban microclimate, we analyze future simulation data across sections crossing urban/non-urban areas, and after grouping them into three classes depending on the location of the grid cells. The urban areas of both cities present increased average minimum temperature (Tmin) in winter/summer compared to ...
Atmospheric Chemistry and Physics Discussions, 2016
The main issue arising from the comparison of ground-based and satellite measurements is the diff... more The main issue arising from the comparison of ground-based and satellite measurements is the difference in spatial representativeness, which for locations with inhomogeneous spatial distribution of pollutants may lead to significant differences between the two datasets. In order to investigate the spatial variability of tropospheric NO<sub>2</sub> within a sub-satellite pixel, a campaign which was lasted for about six months was held at the greater area of Thessaloniki, Greece. Three DOAS/MAX-DOAS systems performed measurements of tropospheric NO<sub>2</sub> columns at different sites representative of urban, sub-urban and rural conditions. The direct comparison of these ground-based measurements with corresponding OMI/Aura and GOME-2/MetOp-A and GOME2/MetOp-B products showed good agreement only over the rural area. GOME2A and GOME2B sensors show an average underestimation of tropospheric NO<sub>2</sub> over the urban area of about 9.12 ±&t...
Atmospheric Environment, 2016
Abstract The main objective of this work is the study of the impact of windblown dust, sea-salt a... more Abstract The main objective of this work is the study of the impact of windblown dust, sea-salt aerosol and biogenic emissions on particle pollution levels in Europe. The Natural Emissions MOdel (NEMO) and the modelling system consisted of the Weather Research and Forecasting model (WRF) and the Comprehensive Air Quality model with extensions (CAMx) were applied in a 30 km horizontal resolution grid, which covered Europe and the adjacent areas for the year 2009. Air quality simulations were performed for different emission scenarios in order to study the contribution of each natural emission source individually and together to air quality levels in Europe. The simulations reveal that the exclusion of windblown dust emissions decreases the mean seasonal PM10 levels by more than 3.3 μg/m 3 (∼20%) in the Eastern Mediterranean during winter while an impact of 3 μg/m 3 was also found during summer. The results suggest that sea-salt aerosol has a significant effect on PM levels and composition. Eliminating sea-salt emissions reduces PM10 seasonal concentrations by around 10 μg/m 3 in Mediterranean Sea during summer while a decrease of up to 6 μg/m 3 is found in Atlantic Ocean during autumn. Sea-salt particles also interact with the anthropogenic component and therefore their absence in the atmosphere decreases significantly the nitrates in aerosols where shipping activities are present. The exclusion of biogenic emissions in the model runs leads to a significant reduction of secondary organic aerosols of more than 90% while an increase in PM2.5 levels in central Europe and Eastern Mediterranean is found due to their interaction with anthropogenic component.
A high resolution emissions inventory for the port city of Thessaloniki, Greece has been compiled... more A high resolution emissions inventory for the port city of Thessaloniki, Greece has been compiled for the year 2008. The emission model MOSESS, developed in the Laboratory of Atmospheric Physics of the University of Thessaloniki has been employed in order to compile emissions of CO, NOx, SOx, NH3, NMVOCs, PM10 and PM2.5 which are released inside the 62x62 km domain (of 2km resolution centered in the city) from more than 30 emission sources such as: central heating, industries, road and non-road vehicles, aviation, cargo ships and many others. Emphasis was given in the emissions originating from the various processes inside the area of the port (stockpiles, loading operations, machinery etc) as well as to the maritime sector emissions provided that the inventory will be used to access the impact of the port activities emissions on the air quality in the city of Thessaloniki. The calculations were based entirely on real activity information provided by numerous local and national auth...
NATO Science for Peace and Security Series C: Environmental Security, 2013
Primary emissions from natural sources can have a significant effect on air quality as well as ad... more Primary emissions from natural sources can have a significant effect on air quality as well as adverse health effects. Natural aerosols act cumulatively with particles of anthropogenic origin increasing the pollution burden especially over urban areas. When studying manmade pollution these sources should be taken into account. The aim of this study is the quantification of the emissions of particulate matter (PM) originated from natural sources in Europe using a state of the art emission model as well as their comparison with the anthropogenic PM emissions. The contribution of natural sources to the PM pollution levels in the study area is also investigated with the synergy of a meteorological and a photochemical model. Natural emissions are estimated on an hourly basis for the year 2010 over Europe with 30km spatial resolution. Natural PM emissions are estimated using the Natural Emission Model (NEMO) which has been developed in the Laboratory of Atmospheric Physics (LAP) of the Ar...
The aim of this study is the estimation of the future emissions in the area of the large urban ce... more The aim of this study is the estimation of the future emissions in the area of the large urban center of Thessaloniki (Greece) with emphasis on the emissions originated from the maritime sector within the port area of the city which are presented in detail. In addition, the contribution of the future anthropogenic emissions to atmospheric pollution levels in Thessaloniki focusing on PM levels is studied. A 2km spatial resolution anthropogenic gaseous and particulate matter emission inventory has been compiled for the port city of Thessaloniki for the year 2010 with the anthropogenic emission model MOSESS, developed by Laboratory of Atmospheric Physics of the Aristotle University of Thessaloniki. MOSESS was used for the estimation of emissions from several emission sources (road transport, central heating, industries, maritime sector etc) while the natural emission model NEMO was implemented for the calculation of dust, sea salt and biogenic emissions. Maritime emissions originated f...
The aim of this study is the quantification of the emissions of particulate matter originated fro... more The aim of this study is the quantification of the emissions of particulate matter originated from natural sources, focusing on windblown dust and sea salt, in the Eastern Mediterranean as well as their dependence on meteorology. Natural emissions are estimated on an hourly basis for a full year run over the Balkan region with 10km spatial resolution using the Natural Emission Model (NEMO). NEMO is driven by WRF meteorology. The methodology for the estimation of dust emissions uses a complex parameterization of wind speed as a function of soil particle size, soil moisture and drag partitioning. Sea salt emissions are dependent on wind speed, sea surface temperature and water salinity. The spatial and temporal distribution of natural emissions in comparison with the aforementioned meteorological parameters is studied. Sea salt emissions are higher during summer and autumn when sea surface temperature is higher while they become maximum in autumn because of the highest wind speed valu...
2006 First International Symposium on Environment Identities and Mediterranean Area, 2006
... tr Selahattin Incecik, Sema Toppu Faculty ofAeronautics and Astronautics, Department of Meteo... more ... tr Selahattin Incecik, Sema Toppu Faculty ofAeronautics and Astronautics, Department of Meteorology Engineering Istanbul Technical University 34469 Maslak Istanbul TURKEY incecik@d,itu.edu.tr,stopcu@d,itu.edu. tr Abstract ...
Springer Atmospheric Sciences, 2012
ABSTRACT Aim of this work is to study the impact of the intense forest fires that tookplace in Gr... more ABSTRACT Aim of this work is to study the impact of the intense forest fires that tookplace in Greece at the end of summer 2007 on the air quality in the Eastern Mediterranean. For this reason the meteorological model MM5 and the photochemical model CAMx are applied over the study area with 10 km spatial resolution. CAMx model is implemented for two emission scenarios; with and without biomass burning emissions. High spatial resolution wildfire emission data are used that are based on the Global Fire Emissions Database (GFED3). The CAMx chemical boundary conditions are taken from the TM4 global model. The nonradiative impact on the composition of the atmosphere and on environmental indices (e.g. Aggregate Risk Index) is quantified in regional scale. The impact of the atmospheric processes on the air pollution levels due to the biomass burning event is also studied giving more emphasis on the boundary layer. The intense biomass burning event in the Eastern Mediterranean at the end of August 2007 results in an enhancement of the CO, NOx and PM2.5 concentrations over almost all the study area, which can range from several times to two order of magnitude over the fire hot spots. The increases in O3 levels are less pronounced and are found mainly downwind the burnt areas. On the 25th August 2007, when fire counts in the study area are maximum, in the daytime boundary layer, the inclusion of biomass burning emissions results in a change of the chemical regime from O3 destruction to O3 production.
Water, Air, & Soil Pollution, 2014
Atmospheric Environment, 2015
h i g h l i g h t s The Balkan a posteriori NO x emissions inventory resulted in 1.11 Tg N/y. Fos... more h i g h l i g h t s The Balkan a posteriori NO x emissions inventory resulted in 1.11 Tg N/y. Fossil fuel NO x emissions over Greece comprise of the 80% of the total emissions. Soil emissions, omitted in a priori, accounted for 20% of the total over Greece. Microbial activity emissions are important in high resolution emission inventories. Biomass burning NO x emission rate, accounted for 0.5 Â 10 À6 Tg N/km 2 over Greece.
The main objective of the present study is the assessment of the non-radiative impact on the lowe... more The main objective of the present study is the assessment of the non-radiative impact on the lower troposphere air quality of the intense biomass burning events that took place in the Eastern Mediterranean, when wild forest fires were burning in Peloponnesus (Greece) at the end of August 2007. The MM5-CAMx modeling system was applied in the Eastern Mediterranean in high spatial and temporal resolution for the period 23 to 31 August 2007, forced by biomass burning emission fluxes from the Global Fire Emissions Database (version 3.0), in day-today temporal and 0.1°spatial variability from the Global Fire Assimilation System. Enhancements of the CO and NOx concentrations over almost the entire modeling domain were estimated due to the biomass burning, which were more pronounced over the burnt areas and maximum over the Peloponnesus forest fires. The domain-wide near surface mean concentration was higher by +6% for CO and +11% for NOx because of the biomass burning. The near surface O 3 values were reduced over the fire hot spots but increased over the greater part of the modeling domain. On the 26th August 2007, the maximum O 3 concentrations reduction of about 12 ppb (i.e. −34%) was calculated over the Peloponnesus fires while the highest O 3 increase of about 27 ppb (i.e. +52%) was estimated over the sea at 500 km downwind the Peloponnesus large forest fires. The process analysis revealed that on that day, the inclusion of the biomass burning emissions resulted in an enhancement of the daytime gas phase O 3 production in the boundary layer in the Eastern Mediterranean and during some daytime hours in a change of the chemical regime from O 3 destruction to O 3 production. From 6 to 16 UTC, the O 3 photochemistry in the boundary layer was VOC-sensitive close to the Peloponnesus fires, gradually changing to NOx-sensitive in the downwind fire plume. In the same period, the maximum impact on the oxidizing capacity of the boundary layer was an increase by 0.25 ppt for OH and a reduction by 13 ppt for HO 2 mean concentrations over the Peloponnesus forest fires and an increase by 12 ppt for HO 2 in the downwind plume.
Aerosol levels at Mediterranean Basin are significantly affected by desert dust that is eroded in... more Aerosol levels at Mediterranean Basin are significantly affected by desert dust that is eroded in North Africa and is transported northwards. This study aims to assess the performance of the Dust REgional Atmospheric Model (BSC-DREAM8b) in the prediction of dust outbreaks near the surface in Eastern Mediterranean. For this purpose, model PM10 predictions covering a 7-year period and PM10 observations at five surface monitoring sites in Greece are used. A quantitative criterion is set to select the significant dust outbreaks defined as those when the predicted PM10 surface concentration exceeds 12 μg/m 3. The analysis reveals that significant dust transport is usually observed for 1-3 consecutive days. Dust outbreak seasons are spring and summer, while some events are also forecasted in autumn. The seasonal variability of dust transport events is different at Finokalia, where the majority of events are observed in spring and winter. Dust contributes by 19-25% to the near surface observed PM10 levels, which can be increased to more than 50 μg/m 3 during dust outbreaks, inducing violations of the air quality standards. Dust regional modeling can be regarded as a useful tool for air quality managers when assessing compliance with air quality limit values.
Springer Atmospheric Sciences, 2012
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Papers by Dimitrios Melas