On the applicability of the Roothaan-Bagus procedure

Tsilimigras, P.

doi:10.1016/0009-2614(71)80541-9

Cited by 2 publications

(4 citation statements)

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“…The OPAC programming software comprises of two sections, the initial segment is a dataset of microphysical properties and the subsequent optical properties of cloud and aerosols components at various wavelengths and for different relative humidity conditions [18,33]. The other part is a FORTRAN program that permits the user to separate information from this dataset, to compute extra optical properties, and to ascertain optical properties of the mixtures of the stored cloud and aerosols components [18,33]. The dataset gives the microphysical and optical properties for six kinds of water clouds, three ice mists, and 10 aerosols components.…”

Section: The Opac Software Packagementioning

confidence: 99%

“…For functional use, the values must be multiplied by the total number density. On account of those aerosols components that can take up water, data for eight values of relative humidities (0%, 50%, 70%, 80%, 90%, 95%, 98%, 99%) are given [18,33]. The information is stored as ASCII files, one record for each cloud or aerosols component and for each relative humidities.…”

Section: The Opac Software Packagementioning

confidence: 99%

“…First, single cloud or aerosols segments can be chosen, and all or a portion of their optical properties can be extracted or determined from the dataset. Second, it is feasible to choose one of those combinations of the aerosol's components, which are proposed as default values in OPAC, or to characterize an extra mixture and to obtain its optical properties [18,33]. Height placement of aerosols particles is given but may likewise be changed with information given by the user.…”

Section: The Opac Software Packagementioning

confidence: 99%

“…For versatility, the program is disseminated as FORTRAN source code. All mandatory input to the program must be entered as an ASCII text document [18,33].…”

Section: The Opac Software Packagementioning

confidence: 99%

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Impacts of the Variations of Aerosols Components and Relative Humidity on the Visibility and Particles Size Distribution of the Desert Atmosphere

Yerima

Abdulkarim

Tijjani

et al. 2021

AJR2P

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This paper investigates the Impact of relative humidity, varying the concentrations of water-soluble aerosol particle concentrations (WASO), Mineral Nuclei Mode Aerosols Particle Concentration (MINN), mineral accumulation mode, nonspherical (MIAN) aerosol particles concentrations and Mineral Coarse Mode Aerosols Particle Concentration (MICN) on the visibility and particles size distribution of desert aerosols based on microphysical properties of desert aerosols. The microphysical properties (the extinction coefficients, volume mix ratios, dry mode radii and wet mode radii) were extracted from Optical Properties of Aerosols and Clouds (OPAC 4.0) at eight relative humidities, RHs (00 to 99%) and at the spectral visible range of 0.4-0.8mm, the concentrations were varied to obtain five different models for each above-mentioned component. Regression analysis of some standard equations were used to determine the Angstrom exponent (α), the turbidity coefficient (β), the curvature (α2), humidification factor (), the mean exponent of aerosol growth curve (µ) and the mean exponent of aerosol size distributions (n). The values of angstrom exponent (α) were observed to be less than 1 throughout the five models at all RHs for the four studied components, and this signifies the dominance of coarse mode particles over fine mode particles. But the magnitude of the angstrom exponent (α) fluctuates all through the studied components except for WASO which increased with the increase in RH across the models and this also signifies the dominance of coarse mode particles with some traces of fine mode particles. The investigation also revealed that the curvature (α2) has both monomodal (negative signs) and bimodal (positive signs) types of distributions all through the five models and this also signifies the dominance of coarse mode particles with some traces of fine mode particles across the individual models for all the studied components. it was also found that the visibility decreased with the increase in RH and increased with the increase in wavelength. The investigation further revealed that the turbidity coefficient (β) fluctuates with the increase in RH and the particles concentrations, and this might be due to major coagulation and sedimentation. The analysis further found that there is a direct inverse power relation between the humidification factor and the mean exponent of aerosols size distribution with the mean exponent of aerosols growth curve. It was also found that as the magnitude of µ increased for MIAN, MINN and MICN, the effective hygroscopic growth decreased. For WASO, it was found that as the magnitude of µ decreased, the effective hygroscopic growth increased with the increase in particles concentrations and RH. The decreased in the magnitude of µ for WASO might be due to the fact that as we increase the non-hygroscopic particles, we decrease the deliquescence. The mean exponent of aerosol size distribution (n) being less than 3 shows foggy condition of the desert atmosphere the four investigated components and five studied models.

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Section: The Opac Software Packagementioning

confidence: 99%

Section: The Opac Software Packagementioning

confidence: 99%

Section: The Opac Software Packagementioning

confidence: 99%

“…For versatility, the program is disseminated as FORTRAN source code. All mandatory input to the program must be entered as an ASCII text document [18,33].…”

Section: The Opac Software Packagementioning

confidence: 99%

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