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Dust transport over the eastern Mediterranean derived from Total Ozone Mapping Spectrometer, Aerosol Robotic Network, and surface measurements

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2007-02-07
Kalivitis, N.
Gerasopoulos, E.
Vrekoussis, M.
Kouvarakis, G.
Kubilay, N.
Hatzianastassiou, N.
Vardavas, I.
Mihalopoulos, N.
Multiyear surface PM10 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. An 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 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 PM10, 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 PM10 and AOT was observed during VET as well, indicating that AOT levels from AERONET may be estimated by PM10 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.