Annual variations of physical properties of desert dust over Israel

Abstract

The annual variation of the desert dust aerosol loading above the eastern Mediterranean is studied. Three periods are identified, March–May, July–August, and September–November, for which the properties of dust particles are distinctly different. The dust layers are at higher altitudes and consist of larger particles in summer and autumn than in spring. The real part of the refractive index of the particles is the same for summer and autumn periods and exceeds the real part of the refractive index measured during the spring. The imaginary part of the refractive index is negligible both in spring and in summer, whereas the imaginary refractive index becomes significant in September–November, indicating the presence of absorbing aerosols. The difference is attributed to different sources and desert dust trajectories in these periods. In spring the desert aerosol from the source in Chad is transported to the eastern Mediterranean predominantly along the North African coast. This is the motion associated with Sharav cyclones. The aerosols come to the eastern Mediterranean via Egypt from the sources near the Red Sea in July–August. In autumn the dust arrives to the eastern Mediterranean from the Libyan coast.

Size-segregated mass distributions of aerosols over Eastern Mediterranean: seasonal variability and comparison with AERONET columnar size-distributions

“…8b the average volume size distributions obtained from the AERONET-FORTH sun photometer were deployed to introduce the columnar information. Similar procedure using the AERONET data has been applied from Israelevich et al (2003) for desert dust aerosol over Israel. It should be noted that the SDI provides mass distributions based on the aerodynamic diameter of the particles, while the AERONET volume distributions refer to physical or stokes diameter (identical for smooth, spherical particles).…”

Origin and pathways of the mineral dust transport to two Spanish EARLINET sites: Effect on the observed columnar and range-resolved dust optical properties

“…Other measurements covered longer time periods (Cachorro et al, 2000;Formenti et al, 2001;Sabbah et al, 2001;Tanre et al, 2001;Gerasopoulos et al, 2003;Israelevich et al, 2003;Esposito et al, 2004;Pavese et al, 2009). Analyses based on satellite observations were also performed to identify the transport of Saharan dust (e.g.…”

Synoptic conditions favouring the occurrence of aerosol episodes over the broader Mediterranean basin

“…Israelevich et al (2003) studied the annual variation of desert dust over the eastern Mediterranean for the warm period of the year and defined its properties, source regions and transport pathways. The synoptic conditions associated with dust transportation towards the central Mediterranean and Europe, based on Aerosol Index (AI) values from the Total Ozone Mapping Spectrometer (TOMS), were analysed by Barkan et al (2005) for the period 1979-1992.…”