scholarly journals Scattering matrices of mineral dust aerosols: a refinement of the refractive index impact

2020 ◽  
Vol 20 (5) ◽  
pp. 2865-2876 ◽  
Author(s):  
Yifan Huang ◽  
Chao Liu ◽  
Bin Yao ◽  
Yan Yin ◽  
Lei Bi
Keyword(s):  
Optical Properties ◽  
Radiative Forcing ◽  
Mineral Dust ◽  
Geometric Model ◽  
Scattering Matrix ◽  
Dust Particles ◽  
Matrix Elements ◽  
Direct Measurements ◽  
Scattering Matrix Elements ◽  
Pseudospectral Time Domain Method

Abstract. Mineral dust, as one of the most important aerosols, plays a crucial role in the atmosphere by directly interacting with radiation, while there are significant uncertainties in determining dust optical properties to quantify radiative effects and to retrieve their properties. Laboratory and in situ measurements of the refractive indices (RIs) of dust differ, and different RIs have been applied in numerical studies used for model developments, aerosol retrievals, and radiative forcing simulations. This study reveals the importance of the dust RI for the development of a model of dust optical properties. The Koch-fractal polyhedron is used as the modeled geometry, and the pseudospectral time domain method and improved geometric-optics method are combined for optical property simulations over the complete size range. We find that the scattering matrix elements of different kinds of dust particles are reasonably reproduced by choosing appropriate RIs, even when using a fixed particle geometry. The uncertainty of the RI would greatly affect the determination of the geometric model, as a change in the RI, even in the widely accepted RI range, strongly affects the shape parameters used to reproduce the measured dust scattering matrix elements. A further comparison shows that the RI influences the scattering matrix elements in a different way than geometric factors, and, more specifically, the P11, P12, and P22 elements seem more sensitive to the RI of dust. In summary, more efforts should be devoted to account for the uncertainties on the dust RI in modeling its optical properties, and the development of corresponding optical models can potentially be simplified by considering only variations over different RIs. Considerably more research, especially from direct measurements, should be carried out to better constrain the uncertainties related to the dust aerosol RIs.

scholarly journals Scattering matrices of mineral dust aerosols: a refinement of the refractive index impact

2019 ◽  
Author(s):  
Yifan Huang ◽  
Chao Liu ◽  
Yan Yin ◽  
Lei Bi
Keyword(s):  
Optical Properties ◽  
Radiative Forcing ◽  
Geometric Model ◽  
Model Development ◽  
Scattering Matrix ◽  
Dust Particles ◽  
Matrix Elements ◽  
Direct Measurements ◽  
Geometric Factors ◽  
Scattering Matrix Elements

Abstract. Dust, as one of the most important aerosols, plays a crucial role in the atmosphere by directly scattering and absorbing solar and infrared radiation, while there are significant uncertainties in determining dust optical properties to quantify radiative effects and to retrieve their properties. Both laboratory and in situ measurements show variations in dust refractive indices (RIs), and different RIs have been applied in different numerical studies of model developments, aerosol retrievals, and radiative forcing simulations. This study reveals the importance of the dust RI for the model development of its optical properties. The Koch-fractal polyhedron is used as the modeled geometry, and the pseudo-spectral time domain method and improved geometric-optics method are combined to cover optical property simulations over the entire size range. Our results indicate that the scattering matrix elements of different kinds of dust particles can be reasonably reproduced by choosing appropriate RIs even using a fixed particle geometry. The uncertainty of the RI would greatly affect the determination of the geometric model, as a change in the RI, even in the widely accepted RI range, strongly affects the appropriate shape parameters to reproduce the measured dust phase matrix elements. A further comparison shows that the RI influences the scattering matrix elements differently from geometric factors, and, more specifically, the P11, P12, and P22 elements seem more sensitive to dust RI. In summary, more efforts should be devoted to account for the uncertainties on the dust RI in modeling its optical properties, and the development of corresponding optical models can potentially be simplified by considering only variations over different RIs. Considerably more research, especially from direct measurements, should be carried out to better constrain the uncertainties related to the dust aerosol RIs.

scholarly journals The spatial distribution of mineral dust and its shortwave radiative forcing over North Africa: modeling sensitivities to dust emissions and aerosol size treatments

2010 ◽  
Vol 10 (18) ◽  
pp. 8821-8838 ◽  
Author(s):  
C. Zhao ◽  
X. Liu ◽  
L. R. Leung ◽  
B. Johnson ◽  
S. A. McFarlane ◽  
...  
Keyword(s):  
North Africa ◽  
Radiative Forcing ◽  
Mineral Dust ◽  
Regional Climate ◽  
Dust Emission ◽  
Radiative Properties ◽  
Lower Atmosphere ◽  
Dust Particles ◽  
Dust Emissions ◽  
Sahel Region

Abstract. A fully coupled meteorology-chemistry-aerosol model (WRF-Chem) is applied to simulate mineral dust and its shortwave (SW) radiative forcing over North Africa. Two dust emission schemes (GOCART and DUSTRAN) and two aerosol models (MADE/SORGAM and MOSAIC) are adopted in simulations to investigate the modeling sensitivities to dust emissions and aerosol size treatments. The modeled size distribution and spatial variability of mineral dust and its radiative properties are evaluated using measurements (ground-based, aircraft, and satellites) during the AMMA SOP0 campaign from 6 January to 3 February of 2006 (the SOP0 period) over North Africa. Two dust emission schemes generally simulate similar spatial distributions and temporal evolutions of dust emissions. Simulations using the GOCART scheme with different initial (emitted) dust size distributions require ~40% difference in total emitted dust mass to produce similar SW radiative forcing of dust over the Sahel region. The modal approach of MADE/SORGAM retains 25% more fine dust particles (radius<1.25 μm) but 8% less coarse dust particles (radius>1.25 μm) than the sectional approach of MOSAIC in simulations using the same size-resolved dust emissions. Consequently, MADE/SORGAM simulates 11% higher AOD, up to 13% lower SW dust heating rate, and 15% larger (more negative) SW dust radiative forcing at the surface than MOSAIC over the Sahel region. In the daytime of the SOP0 period, the model simulations show that the mineral dust heats the lower atmosphere with an average rate of 0.8 ± 0.5 K day−1 over the Niamey vicinity and 0.5 ± 0.2 K day−1 over North Africa and reduces the downwelling SW radiation at the surface by up to 58 W m−2 with an average of 22 W m−2 over North Africa. This highlights the importance of including dust radiative impact in understanding the regional climate of North Africa. When compared to the available measurements, the WRF-Chem simulations can generally capture the measured features of mineral dust and its radiative properties over North Africa, suggesting that the model is suitable for more extensive simulations of dust impact on regional climate over North Africa.

scholarly journals FROM ANDERSON LOCALIZATION TO MESOSCOPIC PHYSICS

2010 ◽  
Vol 24 (12n13) ◽  
pp. 1555-1576 ◽  
Author(s):  
Markus Büttiker ◽  
Michael Moskalets
Keyword(s):  
Electron Transport ◽  
Anderson Localization ◽  
Transport Phenomena ◽  
Scattering Matrix ◽  
Scaling Theory ◽  
Single Electron ◽  
Mesoscopic Physics ◽  
Matrix Elements ◽  
Electron Interference ◽  
Scattering Matrix Elements

In the late seventies an increasing interest in the scaling theory of Anderson localization led to new efforts to understand the conductance of systems which scatter electrons elastically. The conductance and its relation to the scattering matrix emerged as an important subject. This, coupled with the desire to find explicit manifestations of single electron interference, led to the emergence of mesoscopic physics. We review electron transport phenomena which can be expressed elegantly in terms of the scattering matrix. Of particular interest are phenomena which depend not only on transmission probabilities but on both amplitude and phase of scattering matrix elements.

scholarly journals Scattering matrix elements of biological particles measured in a flow through system: theory and practice

1989 ◽  
Vol 28 (10) ◽  
pp. 1752 ◽  
Author(s):  
Peter M. A. Sloot ◽  
Alfons G. Hoekstra ◽  
Hans van der Liet ◽  
Carl G. Figdor
Keyword(s):  
System Theory ◽  
Scattering Matrix ◽  
Theory And Practice ◽  
Matrix Elements ◽  
Biological Particles ◽  
Flow Through ◽  
Scattering Matrix Elements
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