Evaluation of a sectional representation of size distributions for calculating aerosol optical properties

1996 ◽  
Vol 101 (D14) ◽  
pp. 19277-19283 ◽  
Author(s):  
X. A. Wu ◽  
C. Seigneur ◽  
R. W. Bergstrom
Keyword(s):  
Optical Properties ◽  
Size Distributions ◽  
Aerosol Optical Properties

scholarly journals Estimating cloud condensation nuclei number concentrations using aerosol optical properties: role of particle number size distribution and parameterization

2019 ◽  
Vol 19 (24) ◽  
pp. 15483-15502 ◽  
Author(s):  
Yicheng Shen ◽  
Aki Virkkula ◽  
Aijun Ding ◽  
Krista Luoma ◽  
Helmi Keskinen ◽  
...  
Keyword(s):  
Optical Properties ◽  
Size Distribution ◽  
Cloud Condensation Nuclei ◽  
Size Distributions ◽  
Condensation Nuclei ◽  
Aerosol Optical Properties ◽  
Average Bias ◽  
Angstrom Exponent ◽  
Ångström Exponent ◽  
Ångstrom Exponent

Abstract. The concentration of cloud condensation nuclei (CCN) is an essential parameter affecting aerosol–cloud interactions within warm clouds. Long-term CCN number concentration (NCCN) data are scarce; there are a lot more data on aerosol optical properties (AOPs). It is therefore valuable to derive parameterizations for estimating NCCN from AOP measurements. Such parameterizations have already been made, and in the present work a new parameterization is presented. The relationships between NCCN, AOPs, and size distributions were investigated based on in situ measurement data from six stations in very different environments around the world. The relationships were used for deriving a parameterization that depends on the scattering Ångström exponent (SAE), backscatter fraction (BSF), and total scattering coefficient (σsp) of PM10 particles. The analysis first showed that the dependence of NCCN on supersaturation (SS) can be described by a logarithmic fit in the range SS <1.1 %, without any theoretical reasoning. The relationship between NCCN and AOPs was parameterized as NCCN≈((286±46)SAE ln(SS/(0.093±0.006))(BSF − BSFmin) + (5.2±3.3))σsp, where BSFmin is the minimum BSF, in practice the 1st percentile of BSF data at a site to be analyzed. At the lowest supersaturations of each site (SS ≈0.1 %), the average bias, defined as the ratio of the AOP-derived and measured NCCN, varied from ∼0.7 to ∼1.9 at most sites except at a Himalayan site where the bias was >4. At SS >0.4 % the average bias ranged from ∼0.7 to ∼1.3 at most sites. For the marine-aerosol-dominated site Ascension Island the bias was higher, ∼1.4–1.9. In other words, at SS >0.4 % NCCN was estimated with an average uncertainty of approximately 30 % by using nephelometer data. The biases were mainly due to the biases in the parameterization related to the scattering Ångström exponent (SAE). The squared correlation coefficients between the AOP-derived and measured NCCN varied from ∼0.5 to ∼0.8. To study the physical explanation of the relationships between NCCN and AOPs, lognormal unimodal particle size distributions were generated and NCCN and AOPs were calculated. The simulation showed that the relationships of NCCN and AOPs are affected by the geometric mean diameter and width of the size distribution and the activation diameter. The relationships of NCCN and AOPs were similar to those of the observed ones.

Long term (2007–2013) observations of columnar aerosol optical properties and retrieved size distributions over Anantapur, India using multi wavelength solar radiometer

2016 ◽  
Vol 142 ◽  
pp. 238-250 ◽  
Author(s):  
K. Raja Obul Reddy ◽  
G. Balakrishnaiah ◽  
K. Rama Gopal ◽  
N. Siva Kumar Reddy ◽  
T. Chakradhar Rao ◽  
...  
Keyword(s):  
Optical Properties ◽  
Size Distributions ◽  
Aerosol Optical Properties ◽  
Multi Wavelength

scholarly journals Estimating CCN number concentrations using aerosol optical properties: Role of particle number size distribution and parameterization

2019 ◽  
Author(s):  
Yicheng Shen ◽  
Aki Virkkula ◽  
Aijun Ding ◽  
Krista Luoma ◽  
Helmi Keskinen ◽  
...  
Keyword(s):  
Optical Properties ◽  
Size Distribution ◽  
Particle Number ◽  
Cloud Condensation Nuclei ◽  
Geometric Mean ◽  
Measurement Data ◽  
Correlation Coefficients ◽  
Size Distributions ◽  
Aerosol Optical Properties ◽  
Average Bias

Abstract. The concentration of cloud condensation nuclei (CCN) is an essential parameter affecting aerosol-cloud interactions within warm clouds. Long-term CCN number concentration (NCCN) data are scarce, there are a lot more data on aerosol optical properties (AOPs). It is therefore valuable to derive parameterizations for estimating NCCN from AOP measurements. Such parameterizatios have been made earlier, in the present work a new one is presented. The relationships between AOPs, NCCN and particle number size distributions were investigated based on in-situ measurement data from six stations in very different environments around the world. The parameterization derived here depends on the scattering Ångström exponent (SAE), backscatter fraction (BSF) and total scattering coefficient (σsp) of PM10 particles. The analysis showed that the dependence of NCCN on supersaturation SS% is logarithmic: NCCN ≈ ((287 ± 45)SAE10ln(SS%/(0.093 ± 0.006))(BSF − BSFmin) + (5.2 ± 3.3))σsp. At the lowest supersaturations of each site (SS% ≈ 0.1) the average bias, defined as the ratio of the AOP-derived and measured NCCN varied from ~ 0.7 to ~ 1.5 at most sites except at a Himalayan site where bias was > 4. At SS% > 0.3 the average bias ranged from ~ 0.7 to ~ 1.3 at all sites. In other words, at SS% > 0.3 NCCN was estimated with an average uncertainty of approximately 30 % by using nephelometer data. The squared correlation coefficients between the AOP-derived and measured NCCN varied from ~ 0.5 to ~ 0.8. The coefficients of the parameterization derived for the different sites were linearly related to each other. To study the explanation of this, lognormal unimodal particle size distributions were generated and NCCN and AOPs were calculated. The simulation yielded similar relationships between the coefficients as in the field data. It also showed that the relationships of the coefficients are affected by the geometric mean diameter and width of the size distribution and the activation diameter.

Temporal and spatial variations of aerosol optical properties over the Korean peninsula during KORUS-AQ

2021 ◽  
pp. 118301
Author(s):  
Yongjoo Choi ◽  
Young Sung Ghim ◽  
Michal Segal Rozenhaimer ◽  
Jens Redemann ◽  
Samuel E. LeBlanc ◽  
...  
Keyword(s):  
Optical Properties ◽  
Korean Peninsula ◽  
Spatial Variations ◽  
Aerosol Optical Properties ◽  
Temporal And Spatial Variations ◽  
Temporal And Spatial

MODELING OF AEROSOL OPTICAL PROPERTIES AT AN INDIAN COASTAL SITE DURING THE 1999 INDOEX FIELD PHASE

2001 ◽  
Vol 32 ◽  
pp. 423-424
Author(s):  
S.C. ALFARO ◽  
L. GOMES ◽  
A. GAUDICHET ◽  
J.L. RAJOT ◽  
J.F. LEON ◽  
...  
Keyword(s):  
Optical Properties ◽  
Field Phase ◽  
Aerosol Optical Properties ◽  
Coastal Site
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