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University of Crete (2006)

Physical properties of aerosol particles affecting climate in the eastern Mediterranean atmosphere

KALIVITIS NIKOLAOS PETROU Καλυβίτης, Νικόλαος Πέτρου

Titre : Physical properties of aerosol particles affecting climate in the eastern Mediterranean atmosphere

Φυσικές ιδιότητες αιωρούμενων σωματιδίων με κλιματικό ενδιαφέρον στην ατμόσφαιρα της ανατολικής Μεσογείου

Auteur : KALIVITIS NIKOLAOS PETROU Καλυβίτης, Νικόλαος Πέτρου

Etablissement de soutenance : University of Crete

Grade : Master of Science (MS) 2006

Résumé
Mediterranean Basin aerosol loads have become the subject of various studies during the last decades, since a variety of aerosol types can be found there, namely marine aerosols, anthropogenic aerosols and desert dust aerosols. The dust aerosols play an important role owing to the proximity of the extended deserted areas of North Africa (e.g., Sahara and Sahel deserts). Several studies have shown the importance of dust generated aerosols not only to the global and regional energy balance, but to the weather forecasting and to rain formation as well. Multiyear surface ΡΜ10 measurements performed on Crete Island, Greece, have been used in conjunction with satellite (Total Ozone Mapping Spectrometer (TOMS)) and ground-based remote sensing measurements (Aerosol Robotic Network (AERONET)) to enhance our understanding of the evolution of mineral dust events over the eastern Mediterranean. Dust particles arrive to Crete mainly when air masses originate from the south. Back trajectories analysis of southerly air masses at altitudes of 1000 and 3000 m over a 5 year period (2000–2005), showed that dust can potentially arrive over Crete, either simultaneously in the lower free troposphere and inside the boundary layer (vertical extended transport (VET)) or initially into the free troposphere with the heavier particles gradually being scavenged inside the boundary layer (free troposphere transport (FTT)). Both pathways present significant seasonal variations, VET transport pattern prevails during autumn and winter, FTT is more frequently met during summer while during spring they are equally observed, but on an annual basis contribute almost equally to the dust transport in the area. During VET the aerosol index (AI) derived from TOMS was significantly correlated with surface ΡΜ10, and in general AI was found to be adequate for the characterization of dust loadings over the eastern Mediterranean on a climatological basis. A significant covariance between ΡΜ10 and AOT was observed during VET as well, indicating that AOT levels from AERONET may be estimated by ΡΜ10 levels at the surface. Surface measurements are thus crucial for the validation of remote sensing measurements and hence are a powerful tool for the investigation of the impact of aerosols on climate.

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Page publiée le 22 novembre 2022