Radiative transfer simulation of dust-like aerosols: Uncertainties from particle shape and refractive index

Abstract The composition, particle shape, number concentration, size distribution, and spatial and temporal distributions of dust aerosols cause significant uncertainties in relevant radiative transfer simulations. The spherical particle approximation has been generally recognized to introduce errors in radiative transfer calculations involving dust aerosols. Although previous studies have attempted to quantify the effect of non-spherical particles, no consensus has been reached as to the significance of the dust aerosols non-spherical effect on flux calculations. For this study, we utilize a newly developed ultra-violet-to-far-infrared spectral database of the single-scattering properties of tri-axial ellipsoidal, mineral dust-like aerosols to study the non-spherical effect on radiative forcing. The radiance and flux differences between the spherical and ellipsoidal models are obtained for various refractive indices and particle size distributions. The errors originating from using the spherical model and the uncertainties in the refractive indices are quantified at both the top and bottom of the atmosphere. The dust non-spherical effect on the net flux and heating rate profile is obtained over the entire range of the solar spectrum. The particle shape effect is found to be related to the dust optical depth and the surface albedo and can be an important uncertainty source in radiative transfer simulation. The particle shape effect is largest over water surfaces and can cause up to a 30% difference in dust forcing at the top of the atmosphere.

[1]  K. Liou,et al.  Geometric-optics-integral-equation method for light scattering by nonspherical ice crystals. , 1996, Applied optics.

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

[3]  Gunnar Myhre,et al.  Global sensitivity experiments of the radiative forcing due to mineral aerosols , 2001 .

[4]  J. Penner,et al.  Introduction to special section: Outstanding problems in quantifying the radiative impacts of mineral dust , 2001 .

[5]  Eric P. Shettle,et al.  Atmospheric Aerosols: Global Climatology and Radiative Characteristics , 1991 .

[6]  Barbara E. Carlson,et al.  Nonsphericity of dust‐like tropospheric aerosols: Implications for aerosol remote sensing and climate modeling , 1995 .

[7]  Arve Kylling,et al.  Radiance and flux simulations for mineral dust aerosols: Assessing the error due to using spherical or spheroidal model particles , 2004 .

[8]  Z. Kam,et al.  Absorption and Scattering of Light by Small Particles , 1998 .

[9]  F. Torricella,et al.  Atmospheric aerosol optical properties: a database of radiative characteristics for different components and classes. , 1997, Applied optics.

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

[11]  Bernhard Mayer,et al.  Atmospheric Chemistry and Physics Technical Note: the Libradtran Software Package for Radiative Transfer Calculations – Description and Examples of Use , 2022 .

[12]  John E. Harries,et al.  Observations of the impact of a major Saharan dust storm on the atmospheric radiation balance , 2006 .

[13]  M. Kahnert,et al.  Mie simulations as an error source in mineral aerosol radiative forcing calculations , 2007 .

[14]  Jean-François Léon,et al.  Application of spheroid models to account for aerosol particle nonsphericity in remote sensing of desert dust , 2006 .

[15]  Paola Formenti,et al.  Using aircraft measurements to determine the refractive index of Saharan dust during the DODO Experiments , 2009 .

[16]  F. X. Kneizys,et al.  AFGL atmospheric constituent profiles (0-120km) , 1986 .

[17]  Hester Volten,et al.  Scattering matrices of mineral aerosol particles at 441.6 nm and 632.8 nm , 2001 .

[18]  Qiang Fu,et al.  Test of Mie-based single-scattering properties of non-spherical dust aerosols in radiative flux calculations , 2009 .

[19]  Olga V. Kalashnikova,et al.  Modeling the radiative properties of nonspherical soil-derived mineral aerosols , 2004 .

[20]  Timo Nousiainen,et al.  Light scattering modeling of small feldspar aerosol particles using polyhedral prisms and spheroids , 2006 .

[21]  B. Albrecht.  Aerosols, Cloud Microphysics, and Fractional Cloudiness , 1989, Science.

[22]  Ping Yang,et al.  Effects of particle nonsphericity and radiation polarization on retrieving dust properties from MODIS observations , 2009 .

[23]  Larry D. Travis,et al.  Capabilities and limitations of a current FORTRAN implementation of the T-matrix method for randomly oriented, rotationally symmetric scatterers , 1998 .

[24]  S. Hook,et al.  The ASTER spectral library version 2.0 , 2009 .

[25]  T. Nousiainen,et al.  Comparison of measured single-scattering matrix of feldspar particles with T-matrix simulations using spheroids , 2003 .

[26]  Zhaokai Meng,et al.  Single-scattering properties of tri-axial ellipsoidal mineral dust aerosols: A database for application to radiative transfer calculations , 2010 .

[27]  Ping Yang,et al.  Single-scattering properties of triaxial ellipsoidal particles for a size parameter range from the Rayleigh to geometric-optics regimes. , 2009, Applied optics.

[28]  Hester Volten,et al.  Aerosol retrievals from AVHRR radiances: effects of particle nonsphericity and absorption and an updated long-term global climatology of aerosol properties , 2003 .

[29]  Olga V. Kalashnikova,et al.  Importance of shapes and compositions of wind‐blown dust particles for remote sensing at solar wavelengths , 2002 .

[30]  Hester Volten,et al.  Experimental determination of scattering matrices of randomly oriented fly ash and clay particles at 442 and 633 nm , 2001 .

[31]  Michael Kahnert,et al.  Reproducing the optical properties of fine desert dust aerosols using ensembles of simple model particles , 2004 .

[32]  K. Stamnes,et al.  Numerically stable algorithm for discrete-ordinate-method radiative transfer in multiple scattering and emitting layered media. , 1988, Applied optics.

[33]  O. Boucher,et al.  Estimates of the direct and indirect radiative forcing due to tropospheric aerosols: A review , 2000 .

[34]  Timo Nousiainen,et al.  Spherical and spheroidal model particles as an error source in aerosol climate forcing and radiance computations: A case study for feldspar aerosols , 2005 .