Aerosol stratification, optical properties and radiative forcing in Venice (Italy) during ADRIEX

Self Cite

ABSTRACT:The Aerosol Direct Radiative Experiment (ADRIEX) took place over the Adriatic and Black Seas during August and September 2004 with the aim of characterizing anthropogenic aerosol in these regions in terms of its physical and optical properties and establishing its impact on radiative balance. Eight successful flights of the UK BAE-146 Facility for Atmospheric Airborne Measurements were completed together with surface-based lidar and AERONET measurements, in conjunction with satellite overpasses. This paper outlines the motivation for the campaign, the methodology and instruments used, describes the synoptic situation and provides an overview of the key results. ADRIEX successfully measured a range of aerosol conditions across the northern Adriatic, Po Valley and Black Sea. Generally two layers of aerosol were found in the vertical: in the flights over the Black Sea and the Po Valley these showed differences in chemical and microphysical properties, whilst over the Adriatic the layers were often more similar. Nitrate aerosol was found to be important in the Po Valley region. The use of new instruments to measure the aerosol chemistry and mixing state and to use this information in determining optical properties is demonstrated. These results are described in much more detail in the subsequent papers of this special issue.

Section: Objective 4: Validation Of Remote-sensing Methods For Industsupporting

confidence: 65%

Aerosol Direct Radiative Impact Experiment (ADRIEX) overview

Highwood

Haywood

Coe

et al. 2007

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“…Figure 7(b) shows theÅngström exponent against time based on the Microtops data and the AERONET data. Comparisons of the lidar optical depths (not shown here) with AERONET are covered in Barnaba et al (2007).…”

Section: Validation Of Optical Properties Using Aircraft Observationsmentioning

confidence: 99%

In situ and remote-sensing measurements of the mean microphysical and optical properties of industrial pollution aerosol during ADRIEX

Osborne

Haywood

2007

ABSTRACT:We present a summary of the principal physical and optical properties of aerosol particles using the FAAM BAE-146 instrumented aircraft during ADRIEX between 27 August and 6 September 2004, augmented by sunphotometer, lidar and satellite retrievals. Observations of anthropogenic aerosol, principally from industrial sources, were concentrated over the northern Adriatic Sea and over the Po Valley close to the aerosol sources. An additional flight was also carried out over the Black Sea to compare east and west European pollution. Measurements show the single-scattering albedo of dry aerosol particles to vary considerably between 0.89 and 0.97 at a wavelength of 0.55 µm, with a campaign mean within the polluted lower free troposphere of 0.92. Although aerosol concentrations varied significantly from day to day and during individual days, the shape of the aerosol size distribution was relatively consistent through the experiment, with no detectable change observed over land and over sea. There is evidence to suggest that the pollution aerosol within the marine boundary layer was younger than that in the elevated layer. Trends in the aerosol volume distribution show consistency with multiple-site AERONET radiometric observations. The aerosol optical depths derived from aircraft measurements show a consistent bias to lower values than both the AERONET and lidar ground-based radiometric observations, differences which can be explained by local variations in the aerosol column loading and by some aircraft instrumental artefacts. Retrievals of the aerosol optical depth and fine-mode (<0.5 µm radius) fraction contribution to the optical depth using MODIS data from the Terra and Aqua satellites show a reasonable level of agreement with the AERONET and aircraft measurements.  Crown

“…This may be due to localized urban pollution in Venice that remained trapped close to the city; some evidence to support this is gathered from an investigation of other Adriatic flights during the campaign . A detailed analysis of the lidar results and comparison with the in situ data for other flights during the entire campaign is discussed by Barnaba et al (2007).…”

Section: In Situ Optical Propertiesmentioning

confidence: 99%

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

Cook

Highwood

Coe

et al. 2007

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.