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Transport and Transformation of Air Pollutants from Europe to the Mediterranan Region

Objetivo

- To identify and quantify the transport and transformation of polluted air masses travelling over the eastern section of the Mediterranean area in order to assess the cross Mediterranean north-south pollution transfer.
- The aim of this project was to study the transport of air pollutants in the Eastern Mediterranean region. Despite the fact that some work had been conducted in the past in order to understand the levels and transport of pollutants to the Western Mediterranean, almost no information was available for the Eastern part of it. In the framework of this project, continuous measurements, experimental campaigns, including research aircraft flights, and model simulations have been conducted during the period 1993-1996 in order to better understand the transport and transformation phenomena in the Eastern Mediterranean. The suggestion that the urban and industrial plumes can travel large distances keeping their characteristics for some days and therefore can affect the air quality in remote locations, urban or rural, has been validated in the frame of this study from surface and airborne measurements as well as from extensive numerical modelling. The surface observations made at the coast of Israel in combination with the airborne measurements in the Eastern Mediterranean Sea showed that this area is influenced by elevated levels of sulphate and nitrate species. Israel is especially affected by high particulate sulphate values.
- From the airborne measurements performed over the Greek territory and more specifically over the Aegean Sea, the Attica peninsula and East Peloponnese, it appears that the air masses are funnelled southwards across the Aegean Sea and the highest levels are observed close to Crete and especially near Peloponnese. This area was found to be influenced by the urban plume of Athens for several days every year. The area South and Southeast of Peloponnese is also affected by the long range transport from the Central Mediterranean and Italy. The airborne measurements along the Northern and Southern Aegean showed that the transport across the Aegean Sea (from north to south) should occur during several days per year. So, polluted air masses from large urban areas like Istanbul or from industrial areas around the Black Sea should be transported across the Aegean Sea towards the Middle East and Africa. Observation of the composition of the pollutant in the air masses reaching the Israeli coast indicates that the primary pollutants were entrapped thousands of kilometres away. The travel time elapsed between pollution entrapment and arrival at the Israeli coast is sufficient to allow the formation of sulphates and nitrates and the deposition and/or transformation of the primary pollutants.
- Extensive numerical modelling has been performed in order to investigate the paths of air pollutants from Europe to the Eastern part of the Mediterranean. One path of transport of air pollutants towards the Eastern Mediterranean is across the straight South of Italy and Greece. This path might be followed either during the warm or the cold period of the year but mainly during spring as it is associated with the prevalence of westerly flow. When this westerly flow over the central part of the Mediterranean is weak and the lower troposphere is quite stable, the plumes of Italy can travel through the gap between Peloponnese and Crete. When it is stronger or from NW directions, the main path of the plumes palles from the South of Crete towards the eastern part of the Mediterranean. The second path of transport is across the Aegean Sea and seems to occur more frequently because of the synoptic conditions and the developed regional-scale circulations. It is the dominant mechanism during summer.
- Model results also showed the significant role that mesoscale local circulations of various types on the dispersion of such plumes and on the definition of air quality at local scales. The time scale for transport of air pollutants from sources located in Eastern Europe towards the Eastern Mediterranean has been shown to be approximately two to three days, while for the transport from the western to the eastern part of the Mediterranean is in general longer.
- Continuous monitoring of the background levels of the primary SO2, Nox and the secondary pollutant 03 at selected sites in the SW Mediterranean Coast of Turkey and at the central Israeli coastline;
- Monitoring of the sulphate and nitrate particulates on an intermitted basis in Turkey and Israel;
- Performance of additional measurements in Israel of other chemical species (CH20, 03, N02, HN02, N03) with the aid of a DOAS instrument;
- Performance of aircraft flights over the Eastern Mediterranean Region with emphasis over the Aegean Sea in order to measure the lower tropospheric concentrations of S02, N0y, 03 and particulates. The first intensive experimental campaign lasted approximately three weeks (June 26 - July 12, 1994). During this period, the research aircraft flew for approximately 80 hours over the Eastern Mediterranean and the Aegean Sea providing measurements of S02, N0x, 03, aerosol sulphate/nitrate, temperature, and relative humidity. In addition to the tasks for this project, flights were performed in order to study the behaviour of the Athens urban plume. The second experimental campaign lasted one week (1-7 July 1995). Approximately 40 hours of additional aircraft research measurements have been performed over Eastern Mediterranean Sea;
- Performance of atmospheric modelling and transport simulations with the aid of an advanced regional/mesoscale modelling system (3-D simulations).

Tema(s)

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Convocatoria de propuestas

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Régimen de financiación

CSC - Cost-sharing contracts

Coordinador

NATIONAL AND KAPODISTRIAN UNIVERSITY OF ATHENS
Aportación de la UE
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Dirección
33,Panespistimioupolis Building Phys 5
15784 ZOGRAPHOS, ATHENS
Grecia

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Coste total
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Participantes (2)