Desert Aerosol in the Mediterranean
A. di Sarra, M. Cacciani, J. DeLuisi, L. De Silvestri, T. Di Iorio, G. Fiocco, P.
Grigioni
Abstract
Tropospheric aerosols may affect climate through different mechanisms. In
particular, aerosols intervene in the water cycle, and may influence the
hydrologic balance. In the Mediterranean a large role is played by desert dust
originating in the Sahara. Mineral dust production depends on soil aridity,
i.e., among other factors, on land use, and precipitationltemperature regimes.
In the Mediterranean, desert dust is mostly transported northward during
spring and summer, driven by low and high pressure systems over north
Africa. In addition, depending on the synoptic situation, anthropogenic
particles and marine aerosols are found over the Mediterranean. The
Mediterranean basin is thus an excellent laboratory to study the complex
interactions of different type of particles with the radiative field, the
hydrological cycle, and clouds. Some results of measurements carried out at
Lampedusa island (35SN, 12.6 E) in 1999, showing the presence of desert
dust and its effects on the radiative field, are described.
1
Introduction
Atmospheric aerosol produce a significant influence on the Earth radiative budget
(e.g. Schwartz and Andreae, 1996), through scattering and absorption of radiation
(direct forcing), and by influencing the cloud nucleation processes and the cloud
microphysical properties (indirect forcing). Mineral or crustal (dust) particles are
among the principal constituents of tropospheric aerosols. It is estimated that a
fraction ranging between 30 and 50% of the total mineral aerosols are of
anthropogenic origin such as produced in soils which have been disturbed by human
activity (Tegen and Fung, 1995; Sokolik and Toon, 1996). Continental aridity is
indicated as the main cause of increased dust flux from the deserts (Rea et aI., 1985;
Pye, 1989), that constitute the most relevant source of these particles. Hyper arid
regions however (mean annual precipitation <80 mm) are less efficient dust sources
than arid regions (Goudie, 1983). The mobilization of dust in the atmosphere is due
A. di Sarra, M. Cacciani, J. DeLuisi, L. De Silvestri, T. Di Iorio, G. Fiocco, P.
Grigioni
Abstract
Tropospheric aerosols may affect climate through different mechanisms. In
particular, aerosols intervene in the water cycle, and may influence the
hydrologic balance. In the Mediterranean a large role is played by desert dust
originating in the Sahara. Mineral dust production depends on soil aridity,
i.e., among other factors, on land use, and precipitationltemperature regimes.
In the Mediterranean, desert dust is mostly transported northward during
spring and summer, driven by low and high pressure systems over north
Africa. In addition, depending on the synoptic situation, anthropogenic
particles and marine aerosols are found over the Mediterranean. The
Mediterranean basin is thus an excellent laboratory to study the complex
interactions of different type of particles with the radiative field, the
hydrological cycle, and clouds. Some results of measurements carried out at
Lampedusa island (35SN, 12.6 E) in 1999, showing the presence of desert
dust and its effects on the radiative field, are described.
1
Introduction
Atmospheric aerosol produce a significant influence on the Earth radiative budget
(e.g. Schwartz and Andreae, 1996), through scattering and absorption of radiation
(direct forcing), and by influencing the cloud nucleation processes and the cloud
microphysical properties (indirect forcing). Mineral or crustal (dust) particles are
among the principal constituents of tropospheric aerosols. It is estimated that a
fraction ranging between 30 and 50% of the total mineral aerosols are of
anthropogenic origin such as produced in soils which have been disturbed by human
activity (Tegen and Fung, 1995; Sokolik and Toon, 1996). Continental aridity is
indicated as the main cause of increased dust flux from the deserts (Rea et aI., 1985;
Pye, 1989), that constitute the most relevant source of these particles. Hyper arid
regions however (mean annual precipitation <80 mm) are less efficient dust sources
than arid regions (Goudie, 1983). The mobilization of dust in the atmosphere is due