Thermal IR radiative properties of mixed mineral dust and biomass aerosol during SAMUM-2

Claas H. Koehler*, Thomas Trautmann, Erwin Lindermeir, Willem Vreeling, Kirsten Lieke, Konrad Kandler, Bernadett Weinzierl, Silke Gross, Matthias Tesche, Manfred Wendisch

*Corresponding author for this work

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    Abstract

    Ground-based high spectral resolution measurements of downwelling radiances from 800 to 1200 cm(-1) were conducted between 20 January and 6 February 2008 within the scope of the SAMUM-2 field experiment. We infer the spectral signature of mixed biomass burning/mineral dust aerosols at the surface from these measurements and at top of the atmosphere from IASI observations. In a case study for a day characterized by the presence of high loads of both dust and biomass we attempt a closure with radiative transfer simulations assuming spherical particles. A detailed sensitivity analysis is performed to investigate the effect of uncertainties in the measurements ingested into the simulation on the simulated radiances. Distinct deviations between modelled and observed radiances are limited to a spectral region characterized by resonance bands in the refractive index. A comparison with results obtained during recent laboratory studies and field experiments reveals, that the deviations could be caused by the aerosol particles' non-sphericity, although an unequivocal discrimination from measurement uncertainties is not possible. Based on radiative transfer simulations we estimate the aerosol's direct radiative effect in the atmospheric window region to be 8 W m(-2) at the surface and 1 W m(-2) at top of the atmosphere.

    Original languageEnglish
    Pages (from-to)751-769
    Number of pages19
    JournalTellus. Series B: Chemical and Physical Meteorology
    Volume63
    Issue number4
    DOIs
    Publication statusPublished - Sep-2011

    Keywords

    • EMITTED RADIANCE INTERFEROMETER
    • OPTICAL-CONSTANTS
    • INFRARED SPECTRORADIOMETER
    • SOFTWARE PACKAGE
    • AMMONIUM-SULFATE
    • SCATTERING
    • SPECTRA
    • CALIBRATION
    • ALGORITHMS
    • PARTICLES

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