Anastasios Mavrakis

A case of nighttime high ozone concentration over the greater Athens area

A cas e of abrupt and significant increase of surface ozone was examined, which is recorded during the night of October 9 th , 2003, over the area of the Thriassion Plain – Greece, being acco mpanied by the occurrence of a wind outbreak during the same period. As this increase cannot be explained by the ordinary diurnal evolution of tropospheric ozone concentration, the possibility of downward stratospheric ozone transport was investigated. It was indeed found that the case is associated with tropopause folding and subsequent stratospheric air intrusion in the upper troposphere over Greece. With the aid of mesoscale modeling, being also supported by the hydraulic theory, it was found that the intense wind outbreak is associated with the development of disturbances in the lee side of the neighbouring mountain ranges. These disturbances contribute to the free troposphere – atmospheric boundary layer interaction, facilitating the transportation of stratospheric air close to the surface, thus resulting to the observed tropospheric ozone increase. Zusammenfassung

Soil degradation, landscape and climate variations in a Mediterranean agro-forest system (Thriasio, Greece): proposal for a desertification indicator using time series analysis

As a contribution to soil degradation and desertification monitoring in the northern Mediterranean basin, the present study investigates long-term climate variations in the traditional agro-forest system of Thriasio Plain (Greece) by examining month average temperature, precipitation, relative humidity, Standardised Precipitation Index (SPI) and de Martonne index time series between 1958 and 2011. In the last twenty years, the area experienced an increased anthropogenic pressure due to urbanisation and industrialisation processes. Results indicate a moderate trend towards a warmer and drier climate with a slight increase in the range of the observed values for precipitation and temperature. Relative humidity decrease by 0.1% per year at both year and month base. Results point out the complexity of climate variations at the local scale and the importance of air humidity trends depending on rainfall and temperature regimes in the Mediterranean basin.

Soil erosion and degradation in a rapidly expanding industrial area of Eastern Mediterranean basin (Thriasio plain, Greece)

This study investigates soil erosion in a rapidly expanding industrial region of Eastern Mediterranean basin (Thriasio plain, Greece), controlling how geomorphology, topography, soil drainage and vegetation cover shape the local erosivity rate. Our results show that Thriasio plain is characterized by medium–low classes of soil vulnerability in the actual environmental conditions. However, in an ‘extreme conditions’ scenario, areas with sharp slope, a branched hydrographical network and low vegetation cover are classified at high vulnerability to soil erosion. A field study has been implemented considering extreme natural conditions (January 2004) driven by rapid snow melting determining an exceptionally high volume of water flooding down to the sea through a seasonal stream. This episode was considered a ‘natural experiment’ when assessing extreme soil erosion conditions. Based on theoretical calculations and field measurements, our results confirm the estimated value of soil erosion under the ‘extreme conditions’ scenario illustrated above.

Generating a “Typical Air Pollutant Day” in Thriasio Plain, Greece

The Thriasio Plain is the first and main industrial zone of Greece. The scope of this paper is to generate “Typical Air Pollutant Day” in Thriasio Plain. For this purpose we used data for the time period 2001–2014. The data were provided from the Ministry of Environment and are hourly concentration values of Sulfur Dioxide, Nitrogen Monoxide and Dioxide, Ozone and daily values of PM10 at Elefsis central station. The results show an improvement of air quality during the last years, especially for Sulfur Dioxide and Nitrogen Monoxide and Dioxide. The time period considered, concurs with the economic and financial crisis in Greece. For Ozone, the results are unclear. Similar results for Ozone were obtained when we compared measurements from the Ministry of Environment’s data for specific days with measurements from the local municipality’s network.