Particle size distributions in the Eastern Mediterranean troposphere

Abstract

Abstract. Atmospheric particle size distributions were measured on Crete island, Greece in the Eastern Mediterranean during an intensive field campaign between 28 August and 20 October, 2005. Our instrumentation combined a differential mobility particle sizer (DMPS) and an aerodynamic particle sizer (APS) and measured number size distributions in the size range 0.018 µm-10 µm. Four time periods with distinct aerosol characteristics were discriminated, two corresponding to marine and polluted air masses, respectively. In marine air, the sub-µm size distributions showed two particle modes centered at 67 nm and 195 nm having total number concentrations between 900 and 2000 cm −3 . In polluted air masses, the size distributions were mainly unimodal with a mode typically centered at 140 nm, with number concentrations varying between 1800 and 2900 cm −3 . Super-µm particles showed number concentrations in the range from 0.01 to 2.5 cm −3 without any clear relation to air mass origin. A small number of short-lived particle nucleation events were recorded, where the calculated particle formation rates ranged between 1.1-1.7 cm −3 s −1 . However, no particle nucleation and growth events comparable to those typical for the continental boundary layer were observed. Particles concentrations (Diameter <50 nm) were low compared to continental boundary layer conditions with an average concentration of 300 cm −3 . The production of sulfuric acid and its subsequently condensation on preexisting particles was exCorrespondence to: N. Mihalopoulos (mihalo@chemistry.uoc.gr) amined with the use of a simplistic box model. These calculations suggested that the day-time evolution of the Aitken particle population was governed mainly by coagulation and that particle formation was absent during most days.

Modelling the dispersion of particle numbers in five European cities

“…A spatially uniform annually average regional PNC background of 1800 particles cm −3 was used for the boundary conditions, based on Kalivitis et al (2008). The regional background values of all other relevant species were extracted from the LOTOS-EUROS computations, at the grid squares surrounding the city.…”

Spatial extent of new particle formation events over the Mediterranean Basin from multiple ground-based and airborne measurements

“…Although the Mediterranean area is particularly sensitive to the future evolution of atmospheric pollutants and climate change, only a few studies related to NPF in this area have been reported so far. Intensive campaigns were conducted on the eastern Spanish coast, in Barcelona and at the Montseny site (Pey et al, 2008;Cusack et al, 2013), while long-term measurements are performed at the Finokalia (Crete) station (Kalivitis et al, 2008(Kalivitis et al, , 2015Manninen et al, 2010;Pikridas et al, 2012), where NPF event days are close to 30 %. The Mediterranean Basin is at the cross section of many different influences: there is a strong anthropogenic influence from densely populated coastal zones, in addition to marine and dust sources, as well as with emissions from Mediterranean forests and shrublands that emit both terpenes and isoprene.…”

Atmospheric new particle formation as a source of CCN in the eastern Mediterranean marine boundary layer

“…New particle formation is frequent in the eastern Mediterranean atmosphere (Petäjä et al, 2007;Kalivitis et al, 2008;Manninen et al, 2010;Kalivitis et al, 2012;Pikridas at al., 2012), although a bit more sparse than in other, mostly continental, European sites (Manninen et al, 2010). Few CCN measurements have been conducted in the eastern Mediterranean (Bougiatioti et al, 2009(Bougiatioti et al, , 2011, and no attempt exist to date to link NPF with CCN in this environment.…”