Pascoal Micolo D. Campos , Angella G. Moses , Ke Li , Bertrand Tchanche , Anabela A. Leitão , José C.M. Pires
{"title":"Aerosol optical properties over three cities of Angola using long term AERONET data","authors":"Pascoal Micolo D. Campos , Angella G. Moses , Ke Li , Bertrand Tchanche , Anabela A. Leitão , José C.M. Pires","doi":"10.1016/j.apr.2025.102559","DOIUrl":null,"url":null,"abstract":"<div><div>Aerosols can influence the climate, by scattering or absorbing solar radiation. The presence of aerosols may also affect human health as their exposure has been linked to pulmonary and cardiovascular diseases. This paper aims to investigate the spatiotemporal trends of aerosol optical properties, the major types of aerosols, the possible sources of the aerosols, and the aerosol radiative forcing at three locations in Angola, namely, Huambo, Lubango, and Namibe, using the Aerosol Robotic Network (AERONET) dataset from 2016 to 2021. The results revealed that at the three sites, there was a decrease in the aerosol optical depth (AOD) during the warm months, a period characterized by rainfall, and the minimum loadings of AOD varied between 0.073 and 0.132. Huambo registered the highest percentages of biomass-burning aerosols (79 %), followed by Lubango (56 %) and Namibe (21 %). The Ångström exponent (AE) at Lubango ranged from 1.48 to 1.52, denoting the existence of fine-mode aerosol particles. The annual mean of the volume size distribution (VSD) showed that among the three sites, Huambo registered the highest concentration of fine-mode aerosols particles (0.053 μm<sup>3</sup>/μm<sup>2</sup>) when compared with Namibe (0.034 μm<sup>3</sup>/μm<sup>2</sup>) and Lubango (0.030 μm<sup>3</sup>/μm<sup>2</sup>). The mean peak radius of the fine particle over the three sites was about 0.15 μm, while the mean peak radius of the coarse particle registered at both Huambo and Lubango (5.06 μm) was greater than the one at Namibe (3.86 μm). Namibe had the highest annual mean of VSD for coarse-mode aerosol particles among all sites. Further, an investigation revealed that the annual mean aerosol radiative forcing (ARF) at the bottom of the atmosphere (BOA) was the highest at Huambo (−53.63 Wm<sup>-2</sup>), while the ARFs at the top of the atmosphere (TOA) varied between −13.91 Wm<sup>-2</sup> and -9.59 Wm<sup>-2</sup>, among the three sites. The annual mean ARF efficiencies (ARFE) showed a higher value at BOA at Lubango (−214.57 Wm<sup>-2</sup> per AOD), whilst at TOA, it was recorded at Huambo (−60.27 Wm<sup>-2</sup> per AOD). The findings obtained from the current study provide a summary of the aerosol optical properties at three sites in Angola, which could enrich the knowledge of the influence of aerosol direct radiative impact over parts of the country and so enhance future climate models of this region.</div></div>","PeriodicalId":8604,"journal":{"name":"Atmospheric Pollution Research","volume":"16 8","pages":"Article 102559"},"PeriodicalIF":3.9000,"publicationDate":"2025-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Atmospheric Pollution Research","FirstCategoryId":"93","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S1309104225001618","RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ENVIRONMENTAL SCIENCES","Score":null,"Total":0}
引用次数: 0
Abstract
Aerosols can influence the climate, by scattering or absorbing solar radiation. The presence of aerosols may also affect human health as their exposure has been linked to pulmonary and cardiovascular diseases. This paper aims to investigate the spatiotemporal trends of aerosol optical properties, the major types of aerosols, the possible sources of the aerosols, and the aerosol radiative forcing at three locations in Angola, namely, Huambo, Lubango, and Namibe, using the Aerosol Robotic Network (AERONET) dataset from 2016 to 2021. The results revealed that at the three sites, there was a decrease in the aerosol optical depth (AOD) during the warm months, a period characterized by rainfall, and the minimum loadings of AOD varied between 0.073 and 0.132. Huambo registered the highest percentages of biomass-burning aerosols (79 %), followed by Lubango (56 %) and Namibe (21 %). The Ångström exponent (AE) at Lubango ranged from 1.48 to 1.52, denoting the existence of fine-mode aerosol particles. The annual mean of the volume size distribution (VSD) showed that among the three sites, Huambo registered the highest concentration of fine-mode aerosols particles (0.053 μm3/μm2) when compared with Namibe (0.034 μm3/μm2) and Lubango (0.030 μm3/μm2). The mean peak radius of the fine particle over the three sites was about 0.15 μm, while the mean peak radius of the coarse particle registered at both Huambo and Lubango (5.06 μm) was greater than the one at Namibe (3.86 μm). Namibe had the highest annual mean of VSD for coarse-mode aerosol particles among all sites. Further, an investigation revealed that the annual mean aerosol radiative forcing (ARF) at the bottom of the atmosphere (BOA) was the highest at Huambo (−53.63 Wm-2), while the ARFs at the top of the atmosphere (TOA) varied between −13.91 Wm-2 and -9.59 Wm-2, among the three sites. The annual mean ARF efficiencies (ARFE) showed a higher value at BOA at Lubango (−214.57 Wm-2 per AOD), whilst at TOA, it was recorded at Huambo (−60.27 Wm-2 per AOD). The findings obtained from the current study provide a summary of the aerosol optical properties at three sites in Angola, which could enrich the knowledge of the influence of aerosol direct radiative impact over parts of the country and so enhance future climate models of this region.
期刊介绍:
Atmospheric Pollution Research (APR) is an international journal designed for the publication of articles on air pollution. Papers should present novel experimental results, theory and modeling of air pollution on local, regional, or global scales. Areas covered are research on inorganic, organic, and persistent organic air pollutants, air quality monitoring, air quality management, atmospheric dispersion and transport, air-surface (soil, water, and vegetation) exchange of pollutants, dry and wet deposition, indoor air quality, exposure assessment, health effects, satellite measurements, natural emissions, atmospheric chemistry, greenhouse gases, and effects on climate change.