A PC-based Mie scattering program for theoretical investigations of the optical properties of atmospheric aerosols as a function of composition and relative humidity

1994 ◽  
Vol 28 (5) ◽  
pp. 803-809 ◽  
Author(s):  
William E. Wilson ◽  
Parker C. Reist
Keyword(s):  
Optical Properties ◽  
Relative Humidity ◽  
Atmospheric Aerosols ◽  
Mie Scattering ◽  
Theoretical Investigations

The influence of relative humidity on the optical properties of atmospheric aerosols

1999 ◽  
Vol 30 ◽  
pp. S639-S640 ◽  
Author(s):  
K. Tavartkiladze ◽  
I. Shengelia ◽  
A. Amiranashvili ◽  
V. Amiranashvili
Keyword(s):  
Optical Properties ◽  
Relative Humidity ◽  
Atmospheric Aerosols

scholarly journals COMPARISON BETWEEN KELVIN RADII AND BULK HYGROSCOPICITY OF MASS AND VOLUME BASED HYGROSCOPICITY PARAMETER FOR ATMOSPHERIC AEROSOLS

2020 ◽  
Vol 4 (2) ◽  
pp. 337-349
Author(s):  
Bello Saadu ◽  
B. I. Tijjani ◽  
S. Bello
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Regression Analysis ◽  
Growth Factors ◽  
Relative Humidity ◽  
Multiple Regression Analysis ◽  
Atmospheric Aerosols ◽  
Atmospheric Modeling ◽  
Hygroscopic Growth ◽  
Microphysical Properties

A mass based and volume based hygroscopicities models were applied to the data extracted from Optical Properties of Aerosols and Clouds (OPAC).The microphysical properties obtained were radii, density, refractive index, mass and volume of the atmospheric aerosols of continental average, continental clean, continental polluted, maritime tropical, maritime polluted, maritime clean, at eight different relative humidity of 0%, 50%, 70%, 80%, 90%, 95%, 98% and 99%.Using the microphysical properties, hygroscopic growth factors and effective radii of the mixtures were determined while the parameters Av and Bv for volume based and Am and Bm for mass based of the aerosols were determined using multiple regression analysis with SPSS 16.0 at each relative humidity. Although it was discovered that Bv is more dominant than Av, the R2 for all the models are greater than 90%. The significances are less than 0.05, Am>Av and Bm<Bv, therefore the two models are good for atmospheric modeling.

Mathematical modelling of remote detection of molecular air pollutants

1987 ◽  
Vol 52 (6) ◽  
pp. 1397-1406
Author(s):  
František Zrcek ◽  
Milan Horák
Keyword(s):  
Atmospheric Aerosols ◽  
Air Pollutants ◽  
Complex Refractive Index ◽  
Mie Scattering ◽  
Heat Emission ◽  
Remote Detection ◽  
Radiation Absorption ◽  
Variable Concentration ◽  
Lidar Equation ◽  
Optical Pathway

A model of remote detection of molecular air pollutants is devised based on the lidar equation. The various kinds of interaction of radiation with matter, viz. absorption, induced fluorescence, and Raman scattering, are taken into account; detection of either scattered or reflected signal is considered. The reflection is assumed to be either axial, using a retroreflector, or omnidirectional from a field target. Based on this model, an algorithm was set up for simulation of the different variants of the experiment, making allowance for a generally variable concentration of the compound along the optical pathway of the light beam. The basic atmospheric processes, viz. radiation absorption by the backround, heat emission, turbulence, and the effect of atmospheric aerosols, are treated, and the last of them is found to play the major role. Aerosols are looked upon as a source of the Mie scattering and they are described by distribution equations with respect to the particle size and the complex refractive index. The variable concentration of the aerosol along the optical pathway and the simultaneous effect of a higher numberof aerosol types are included.

First global assessment of modelled aerosol hygroscopicity in the context of other aerosol optical properties

2021 ◽  
Author(s):  
Maria Ángeles Burgos Simón ◽  
Elisabeth Andrews ◽  
Gloria Titos ◽  
Angela Benedetti ◽  
Huisheng Bian ◽  
...  
Keyword(s):  
Optical Properties ◽  
Light Scattering ◽  
Relative Humidity ◽  
Water Uptake ◽  
Chem Phys ◽  
Earth System ◽  
Aerosol Optical Properties ◽  
System Models ◽  
Earth System Models

&lt;p&gt;The particle hygroscopic growth impacts the optical properties of aerosols and, in turn, affects the aerosol-radiation interaction and calculation of the Earth&amp;#8217;s radiative balance. The dependence of particle light scattering on relative humidity (RH) can be described by the scattering enhancement factor f(RH), defined as the ratio between the particle light scattering coefficient at a given RH divided by its dry value.&lt;/p&gt;&lt;p&gt;The first effort of the AeroCom Phase III &amp;#8211; INSITU experiment was to develop an observational dataset of scattering enhancement values at 26 sites to study the uptake of water by atmospheric aerosols, and evaluate f(RH) globally (Burgos et al., 2019). Model outputs from 10 Earth System Models (CAM, CAM-ATRAS, CAM-Oslo, GEOS-Chem, GEOS-GOCART, MERRAero, TM5, OsloCTM3, IFS-AER, and ECMWF) were then evaluated against this in-situ dataset. Building on these results, we investigate f(RH) in the context of other aerosol optical and chemical properties, making use of the same 10 Earth System Models (ESMs) and in-situ measurements as in Burgos et al. (2020) and Titos et al. (2021).&lt;/p&gt;&lt;p&gt;Given the difficulties of deploying and maintaining instrumentation for long-term, accurate and comprehensive f(RH) observations, it is desirable to find an observational proxy for f(RH). This observation-based proxy would also need to be reproduced in modelling space. Our aim here is to evaluate how ESMs currently represent the relationship between f(RH), scattering &amp;#197;ngstr&amp;#246;m exponent (SAE), and single scattering albedo (SSA). This work helps to identify current challenges in modelling water-uptake by aerosols and their impact on aerosol optical properties within Earth system models.&lt;/p&gt;&lt;p&gt;We start by analyzing the behavior of SSA with RH, finding the expected increase with RH for all site types and models. Then, we analyze the three variables together (f(RH)-SSA-SAE relationship). Results show that hygroscopic particles tend to be bigger and scatter more than non-hygroscopic small particles, though variability within models is noticeable. This relationship can be further studied by relating SAE to model chemistry, by selecting those grid points dominated by a single chemical component (mass mixing ratios &gt; 90%). Finally, we analyze model performance at three specific sites representing different aerosol types: Arctic, marine and rural. At these sites, the model data can be exactly temporally and spatially collocated with the observations, which should help to identify the models which exhibit better agreement with measurements and for which aerosol type.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;Burgos, M.A.&amp;#160;et al.:&amp;#160;A global view on the effect of water uptake on aerosol particle light scattering.&amp;#160;Sci Data&amp;#160;6,&amp;#160;157. https://doi.org/10.1038/s41597-019-0158-7, 2019.&lt;/p&gt;&lt;p&gt;Burgos, M.A. et al.: A global model&amp;#8211;measurement evaluation of particle light scattering coefficients at elevated relative humidity, Atmos. Chem. Phys., 20, 10231&amp;#8211;10258, https://doi.org/10.5194/acp-20-10231-2020, 2020.&lt;/p&gt;&lt;p&gt;Titos, G. et al.: A global study of hygroscopicity-driven light scattering enhancement in the context of other in-situ aerosol optical properties, Atmos. Chem. Phys. Discuss. [preprint], https://doi.org/10.5194/acp-2020-1250, in review, 2020.&lt;/p&gt;

scholarly journals A new approach for retrieving the UV–vis optical properties of ambient aerosols

2016 ◽  
Vol 9 (8) ◽  
pp. 3477-3490 ◽  
Author(s):  
Nir Bluvshtein ◽  
J. Michel Flores ◽  
Lior Segev ◽  
Yinon Rudich
Keyword(s):  
Optical Properties ◽  
Atmospheric Aerosols ◽  
Radiative Forcing ◽  
Complex Refractive Index ◽  
Single Scattering ◽  
Aerosol Size Distribution ◽  
Distribution Data ◽  
Ambient Aerosols ◽  
New Approach ◽  
Effective Radiative Forcing

Abstract. Atmospheric aerosols play an important part in the Earth's energy budget by scattering and absorbing incoming solar and outgoing terrestrial radiation. To quantify the effective radiative forcing due to aerosol–radiation interactions, researchers must obtain a detailed understanding of the spectrally dependent intensive and extensive optical properties of different aerosol types. Our new approach retrieves the optical coefficients and the single-scattering albedo of the total aerosol population over 300 to 650 nm wavelength, using extinction measurements from a broadband cavity-enhanced spectrometer at 315 to 345 nm and 390 to 420 nm, extinction and absorption measurements at 404 nm from a photoacoustic cell coupled to a cavity ring-down spectrometer, and scattering measurements from a three-wavelength integrating nephelometer. By combining these measurements with aerosol size distribution data, we retrieved the time- and wavelength-dependent effective complex refractive index of the aerosols. Retrieval simulations and laboratory measurements of brown carbon proxies showed low absolute errors and good agreement with expected and reported values. Finally, we implemented this new broadband method to achieve continuous spectral- and time-dependent monitoring of ambient aerosol population, including, for the first time, extinction measurements using cavity-enhanced spectrometry in the 315 to 345 nm UV range, in which significant light absorption may occur.

scholarly journals PROCESSING JUMP POINT OF LIDAR DETECTION DATA AND INVERSING THE AEROSOL EXTINCTION COEFFICIENT

2019 ◽  
Vol XLII-3/W9 ◽  
pp. 227-232
Author(s):  
H. L. Zhang ◽  
H. Zhao ◽  
Y. P. Liu ◽  
X. K. Wang ◽  
C. Shu
Keyword(s):  
Atmospheric Aerosols ◽  
Extinction Coefficient ◽  
Interpolation Method ◽  
Linear Interpolation ◽  
Mie Scattering ◽  
Inversion Method ◽  
Aerosol Extinction ◽  
Detection Range ◽  
Long Time ◽  
Aerosol Extinction Coefficient

Abstract. For a long time, the research of the optical properties of atmospheric aerosols has aroused a wide concern in the field of atmospheric and environmental. Many scholars commonly use the Klett method to invert the lidar return signal of Mie scattering. However, there are always some negative values in the detection data of lidar, which have no actual meaning，and which are jump points. The jump points are also called wild value points and abnormal points. The jump points are refered to the detecting points that are significantly different from the surrounding detection points, and which are not consistent with the actual situation. As a result, when the far end point is selected as the boundary value, the inversion error is too large to successfully invert the extinction coefficient profile. These negative points are jump points, which must be removed in the inversion process. In order to solve the problem, a method of processing jump points of detection data of lidar and the inversion method of aerosol extinction coefficient is proposed in this paper. In this method, when there are few jump points, the linear interpolation method is used to process the jump points. When the number of continuous jump points is large, the function fitting method is used to process the jump points. The feasibility and reliability of this method are verified by using actual lidar data. The results show that the extinction coefficient profile can be successfully inverted when different remote boundary values are chosen. The extinction coefficient profile inverted by this method is more continuous and smoother. The effective detection range of lidar is greatly increased using this method. The extinction coefficient profile is more realistic. The extinction coefficient profile inverted by this method is more favorable to further analysis of the properties of atmospheric aerosol. Therefore, this method has great practical application and popularization value.

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