Effect of Varying Aerosol Concentrations and Relative Humidity on Visibility and Particle Size Distribution in Urban Atmosphere

Abstract

Atmospheric aerosol concentrations have been found to change constantly due to the influence of source, winds and human activities over short time periods. This has proved to be a constraint to the study of varied aerosol concentrations in urban atmosphere alongside changing relative humidity and how it affects visibility and aerosol particle size distribution. In this research simulation was carried out using Optical Properties of Aerosols and Clouds (OPAC 4.0) average concentration setup for relative humidity (RH) 0-99% at visible wavelength 0.4-0.8 μm to vary the concentrations of three aerosol components: WASO (Water-soluble), INSO (Insoluble) and SOOT. The Angstrom exponents (α), the curvatures (α2) and atmospheric turbidities (β) were obtained from the regression analysis of Kaufman’s first and second order polynomial equations for visibility. The research determined the mean exponent of the aerosol size growth curve (µ) from the effective hygroscopic growth (geff) and the humidification factors (γ) from visibility enhancement f (RH, λ). The mean exponent of aerosol size distributions (υ) was determined from µ and γ. The results showed that with varied WASO, INSO and SOOT concentrations respectively at different RH, aerosol particle size distributions showed bimodal characteristics with dominance of fine mode particles. Hazy atmospheric conditions prevailed with increasing turbidity.

Impacts of the Variations of Aerosols Components and Relative Humidity on the Visibility and Particles Size Distribution of the Desert Atmosphere: Validating Results Obtained from OPAC 4.0 using MERRA-2 Model (Angstrom Exponent and Extinction Coefficient) Data

“…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 [4], [9][10][11], [23], [28]. 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.…”

“…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 (Abdulkarim et al 2021; S. U. Yerima, Abdulkarim, Tijjani, Gana, Sani, Aliyu, et al 2021; S. U. Yerima, Abdulkarim, Tijjani, Gana, Sani, and Aliyu 2021; S. U. Yerima, Tijjani, and Gana 2021). The information is stored as ASCII files, one record for each cloud or aerosols component and for each relative humidities.…”

“…Residue from the Sahara is the biggest source of mineral dust in the atmosphere [8][9][10]. It is a wonder of interest for meteorological material science as well as for general wellbeing too, because of the potential health effect of its air dispersal and flow in the atmosphere [11], [12].…”

“…In the natural environments the changes in the microphysical and optical properties observed at a given wavelength with respect to the corresponding change in relative humidity is a signs that measuring condition have changed [4], [9][10][11]. These changes can cause unbalance in the atmosphere by causing decrease in visibility or other harmful effects to man and his environment [10].…”

Layout of Suspension-Type Small-Sized Dehumidifiers Affects Humidity Variability and Energy Consumption in Greenhouses

“…To assess the humidity distribution across time, the humidity response is essential [26]. To determine the humidity distribution under varying circumstances, it is necessary to evaluate the humidity level in various layers and planes [27]. As a result, the humidity condition for dehumidifier operation for different positions, which is normally utilized to study distinct layers on spatial and vertical planes, was used to investigate humidity responsiveness and variability.…”