Modeling the radiative properties of nonspherical soil-derived mineral aerosols

Mineral dust aerosols have complex nonspherical shapes and varying composition. This study utilizes data on morphology (size and shape) and composition of dust particles to determine the extent to which the optical properties of real particles di8er from those of spheres. A method for modeling the optical properties of complex particle mixtures is proposed. The method combines dust particle composition–shape–size (CSS) distributions reconstructed from the electron microscopy data, e8ective medium approximations and discrete dipole approximation. The method is used to compute optical characteristics of realistic dust mixtures representative of Saharan and Asian dust. We demonstrate that considered CSS distributions result in various di8erences in the extinction coe<cient, single scattering albedo, asymmetry parameter and the scattering phase function relative to the volume-equivalent spheres and the mixtures of the randomly oriented oblate and prolate spheroids. Implications of these di8erences for radiation/climate modeling and remote sensing are discussed. ? 2003 Elsevier Ltd. All rights reserved.

[1]  Yuan Gao,et al.  Characteristics of Chinese aerosols determined by individual‐particle analysis , 2001 .

[2]  Sung-Nam Oh,et al.  Chemical composition and source signature of spring aerosol in Seoul, Korea , 2001 .

[3]  Larry D. Travis,et al.  Light scattering by nonspherical particles : theory, measurements, and applications , 1998 .

[4]  Ilan Koren,et al.  On the relation between size and shape of desert dust aerosol , 2001 .

[5]  Robert A. West,et al.  Laboratory measurements of mineral dust scattering phase function and linear polarization , 1997 .

[6]  M. Mishchenko,et al.  Modeling phase functions for dustlike tropospheric aerosols using a shape mixture of randomly oriented polydisperse spheroids , 1997 .

[7]  W. Wiscombe,et al.  Scattering from nonspherical Chebyshev particles. I: cross sections, single-scattering albedo, asymmetry factor, and backscattered fraction. , 1986, Applied optics.

[8]  Zev Levin,et al.  Chemical and mineralogical analysis of individual mineral dust particles , 2001 .

[9]  J. Pollack,et al.  Scattering by nonspherical particles of size comparable to wavelength - A new semi-empirical theory and its application to tropospheric aerosols , 1980 .

[10]  T. Kamiya,et al.  Characteristics of single particles sampled in Japan during the Asian dust}storm period , 2001 .

[11]  W. Wiscombe,et al.  Scattering from nonspherical Chebyshev particles. 2: Means of angular scattering patterns. , 1988, Applied optics.

[12]  Effect of clouds on direct aerosol radiative forcing of climate , 1998 .

[13]  M. Quante,et al.  Comment on error analysis of backscatter from discrete dipole approximation for different ice particle shapes [Liu, C.-L., Illingworth, A.J., 1997, Atmos. Res. 44, 231-241.] , 1998 .

[14]  T. Eck,et al.  Accuracy assessments of aerosol optical properties retrieved from Aerosol Robotic Network (AERONET) Sun and sky radiance measurements , 2000 .

[15]  Takashi Shibata,et al.  Free tropospheric aerosol backscatter, depolarization ratio, and relative humidity measured with the Raman lidar at Nagoya in 1994-1997: contributions of aerosols from the Asian Continent and the Pacific Ocean , 2000 .

[16]  Laboratory studies of scattering matrices for randomly oriented particles: potentials, problems, and perspectives , 2003 .

[17]  Zev Levin,et al.  Composition of individual aerosol particles above the Israelian Mediterranean coast during the summer time , 1998 .

[18]  Irina N. Sokolik,et al.  Incorporation of mineralogical composition into models of the radiative properties of mineral aerosol from UV to IR wavelengths , 1999 .

[19]  I. Sokolik,et al.  Investigation of optical and radiative properties of atmospheric dust aerosols , 1993 .

[20]  Irina N. Sokolik,et al.  Radiative heating rates and direct radiative forcing by mineral dust in cloudy atmospheric conditions , 2000 .

[21]  Michael F. Hochella,et al.  Measuring discrete feature dimensions in AFM images with image SXM , 2003 .

[22]  M. Mishchenko,et al.  Efficient finite-difference time-domain scheme for light scattering by dielectric particles: application to aerosols. , 2000, Applied optics.

[23]  J. Weingartner,et al.  Radiative Torques on Interstellar Grains. II. Grain Alignment , 1996, astro-ph/9611149.

[24]  K. Murphy,et al.  The partitioning of elements in crust-dominated marine aerosols , 1986 .

[25]  Hiroshi Naruse,et al.  Features of Individual Asian Dust-storm Particles Collected at Nagoya, Japan , 1987 .

[26]  Alexander Smirnov,et al.  Comparison of size and morphological measurements of coarse mode dust particles from Africa , 2003 .

[27]  Peter R. Buseck,et al.  Characterization of individual fine-fraction particles from the Arctic aerosol at Spitsbergen, May–June 1987 , 1992 .

[28]  Greg W. Starr,et al.  Evaluation of iteration methods used when modeling scattering from features on surfaces using the discrete-dipole approximation , 1998 .

[29]  Teruyuki Nakajima,et al.  Aerosol Optical Characteristics in the Yellow Sand Events Observed in May, 1982 at Nagasaki-Part II Models , 1989 .

[30]  Anthony J. Illingworth,et al.  Error analysis of backscatter from discrete dipole approximation for different ice particle shapes , 1997 .

[31]  J. Hovenier,et al.  Single scattering of light by circular cylinders. , 1994, Applied optics.

[32]  B. Draine,et al.  Discrete-Dipole Approximation For Scattering Calculations , 1994 .

[33]  Jost Heintzenberg,et al.  Shape of atmospheric mineral particles collected in three Chinese arid‐regions , 2001 .

[34]  Superthermal,et al.  Radiative Torques on Interstellar Grains : I . , 1996 .

[35]  J. Reid,et al.  Characterization of African dust transported to Puerto Rico by individual particle and size segregated bulk analysis , 2003 .

[36]  Daniel J. Jacob,et al.  Minerals in the Air: An Environmental Perspective , 2000 .

[37]  S. Asano,et al.  Light scattering by randomly oriented spheroidal particles. , 1980, Applied optics.