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          Institute: MPI für Chemie     Collection: Publikationen MPI für Chemie     Display Documents



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ID: 18173.0, MPI für Chemie / Publikationen MPI für Chemie
STAAARTE-MED 1998 summer airborne measurements over the Aegean Sea: 2. Aerosol scattering and absorption, and radiative calculations
Authors:Formenti, P.; Boucher, O.; Reiner, T.; Sprung, D.; Andreae, M. O.; Wendisch, M.; Wex, H.; Kindred, D.; Tzortziou, M.; Vasaras, A.; Zerefos, C.
Language:English
Date of Publication (YYYY-MM-DD):2002-11
Title of Journal:Journal of Geophysical Research
Journal Abbrev.:J. Geophys. Res.
Volume:107
Issue / Number:D21
Sequence Number of Article:4451
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:[1] Chemical, physical, and optical measurements of aerosol particle properties within an aged biomass-burning plume were performed on board a research aircraft during a profile descent over a ground-based site in northeastern Greece (40degrees24'N, 23degrees57'E; 170 m asl) where continuous measurements of the spectral downwelling solar irradiance (global, direct, and diffuse) are being made. The aerosol optical depth measured at the ground during the time of overflight was significantly enhanced (0.39 at a wavelength of 500 nm) due to a haze layer between 1 and 3.5 km altitude. The dry particle scattering coefficient within the layer was around 80 Mm(-1), and the particle absorption coefficient was around 15 Mm(-1), giving a single scattering albedo of 0.89 at 500 nm (dry state). The black carbon fraction is estimated to account for 6-9% of the total accumulation mode particle mass (<1 μm diameter). The increase of the particle scattering coefficient with increasing relative humidity at 500 nm is of the order of 40% for a change in relative humidity from 30 to 80%. The dry, altitude- dependent, particle number size distribution is used as input parameter for radiative transfer calculations of the spectral short-wave, downwelling irradiance at the surface. The agreement between the calculated irradiances and the experimental results from the ground-based radiometer is within 10%, both for the direct and the diffuse components (at 415, 501, and 615 nm). Calculations of the net radiative forcing at the surface and at the top of the atmosphere (TOA) show that due to particle absorption the effect of aerosols is much stronger at the surface than at the TOA. Over sea the net short-wave radiative forcing (daytime average) between 280 nm and 4 μm is up to -64 W m(-2) at the surface and up to -22 W m(-2) at the TOA.
Free Keywords:aerosols; Aegean Sea; optical properties; vertical profiles; direct radiative forcing
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Chemie/Biogeochemie
External Affiliations:Ctr Geophys Evora, P-7000671 Evora, Portugal; Met Off, Farnborough GU146 TD, Hants, England; Aristotle Univ Thessaloniki, Lab Atmospher Phys, GR-54006 Thessaloniki, Greece; Inst Tropospher Res, D-04303 Leipzig, Germany
Identifiers:ISI:000180860300002
ISSN:0747-7309
DOI:10.1029/2001JD001536
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