Sensitivity of direct radiative forcing by mineral dust to particle characteristics

Adam J. Durant, Sandy P. Harrison*, I. Matthew Watson, Y. Balkanski

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    30 Citations (Scopus)

    Abstract

    Airborne dust affects the Earth's energy balance - an impact that is measured in terms of the implied change in net radiation (or radiative forcing, in W m-2) at the top of the atmosphere. There remains considerable uncertainty in the magnitude and sign of direct forcing by airborne dust under current climate. Much of this uncertainty stems from simplified assumptions about mineral dust-particle size, composition and shape, which are applied in remote sensing retrievals of dust characteristics and dust-cycle models. Improved estimates of direct radiative forcing by dust will require improved characterization of the spatial variability in particle characteristics to provide reliable information dust optical properties. This includes constraints on: (1) particle-size distribution, including discrimination of particle subpopulations and quantification of the amount of dust in the sub-10 μm to <0.1 μm mass fraction; (2) particle composition, specifically the abundance of iron oxides, and whether particles consist of single or multi-mineral grains; (3) particle shape, including degree of sphericity and surface roughness, as a function of size and mineralogy; and (4) the degree to which dust particles are aggregated together. The use of techniques that measure the size, composition and shape of individual particles will provide a better basis for optical modelling.

    Original languageEnglish
    Pages (from-to)80-102
    Number of pages23
    JournalProgress in Physical Geography
    Volume33
    Issue number1
    DOIs
    Publication statusPublished - 2009

    Keywords

    • Atmospheric dust loading
    • Climate uncertainties
    • Dust-particle properties
    • Mineral dust
    • Radiative forcing

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