A comparison of aerosol optical and chemical properties over the Adriatic and Black Seas during summer 2004: Two case-studies from ADRIEX

Abstract

ABSTRACT:In this study we provide aerosol characteristics for two case-studies from a summertime campaign over the northern Mediterranean region. Airborne measurements over the northern Adriatic and the western coast of the Black Sea provide a vertically resolved picture of aerosol optical, microphysical and chemical properties, and the horizontal variability of pollution across eastern and western Europe. Observed variations in the characteristics can be principally attributed to the source region of each air mass. This is particularly evident in a stratified aerosol profile over the Black Sea that results from an eastern European air mass at low altitudes underlying an air mass originating from central and western Europe. The atmospheric column over the Adriatic was found to be more homogeneous, both optically and in composition, comprising western European industrial pollution. Analysis of the chemical components of the sampled aerosol showed that the elevated pollution layer over the Black Sea was dominated by sulphates, while the lower layer was dominated by organic compounds, most likely due to agricultural fire events that were visible from the aircraft. This difference in chemical composition was reflected in the in situ single-scattering albedo; the lower layer had a mean value of 0.91 while the elevated layer had a higher mean value of 0.95, indicative of a stronger scattering component. Measurements over the Adriatic Sea displayed more consistency in composition between the two layers and a less apparent difference in the single-scattering albedo (SSA; 0.89 and 0.90 for the lower and elevated pollution layers, respectively). Airborne observations are complemented by surface sunphotometer and lidar retrievals, and satellite retrievals where available, and a closure investigation is performed to examine consistency of optical properties between these datasets.

Chemical composition of summertime aerosol in the Po Valley (Italy), northern Adriatic and Black Sea

“…A mixture of profiles, straight and level runs and orbits were conducted over both the Po Valley and Northern Adriatic Sea, in a manner similar to that flown by the Met Office C-130 aircraft during various missions -the Southern African Regional Science Initiative (SAFARI 2000;Haywood et al, 2003), the Saharan Dust Experiment, the Tropospheric Radiative Forcing Observational Experiment, and the second Aerosol Characterization Experiment (SHADE, TARFOX, ACE-2; Osborne and Haywood, 2005). A flight over the Black Sea was also conducted and is described in detail in Cook et al (2007).…”

“…These were often present in the same particles as the inorganic salts (e.g. Cook et al, 2007) indicating the components were often internally mixed.…”

“…This flight is discussed in detail by Cook et al (2007), but is also discussed here to contrast with the Adriatic flights. There are two distinct vertical layers which contain significant amounts of aerosol, both of which are capped by a strong temperature inversion.…”

“…The paper aims to look at the role of airmass history on the measured composition and examine the role of meteorology on the aerosol climatology in the Po Valley and northern Adriatic Sea. An overview of the ADRIEX campaign can be found in Highwood et al (2007), and in situ and remotely sensed optical and radiative properties of aerosol can be found in Osborne et al (2007), Cook et al (2007) and Barnaba et al (2007). Aerosol composition measurements derived from thermograms of optical size distributions taken during ADRIEX can be found in Brooks et al (2007).…”

Aerosol scattering and absorption during the EUCAARI-LONGREX flights of the Facility for Airborne Atmospheric Measurements (FAAM) BAe-146: can measurements and models agree?

“…Volume weighted mixing is often used to combine optical properties (for external mixtures) or refractive indices and density prior to scattering calculations (for internal mixtures) of aerosol components such as sulphates or black carbon (BC) (e.g. Chylek et al, 1988;Osborne et al, 2007;Cook et al, 2007). It is important to quantify the uncertainty with which we know firstly the refractive indices of individual aerosols as measured in the laboratory, and secondly, how mixing the components affects scattering and absorption.…”