Multi-year analysis of aerosol optical properties and implications to radiative forcing over urban Pretoria, South Africa
Multi-year analysis of aerosol optical properties and implications to radiative forcing over urban Pretoria, South Africa
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气溶胶光学特性的多年分析及其对南非比勒陀利亚城市辐射强迫的影响
DOI：
10.1007/s00704-020-03183-7
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发表时间：
2020
影响因子：
3.4
通讯作者：
Devi Nulu Latha
中科院分区：
文献类型：
--
作者：
Kumar Kanike Raghavendra;Boiyo Richard;Khan Rehana;Kang Na;Yu Xingna;Sivakumar Venkataraman;Griffith Derek;Devi Nulu Latha
利用AERONET太阳光度计2011年至2017年在南非西北部城市-工业城市比勒陀利亚(25.75°S，28.28°E)进行的测量，重点研究了气溶胶光学特性和直接气溶胶辐射强迫(DARF)。结果表明，SON(0.28 ± 0.09，1.46 ± 0.16)和DJF(0.24 ± 0.07，1.48 ± 0.18)具有较高的气溶胶光学厚度(AOD440)和AE440-870指数，表明生物质燃烧产生的人为细模气溶胶占主导地位。单次散射反照率(SSA440)最大值为0.90 ± 0.05，最小值为0.85 ± 0.04。浓度加权轨迹(CWT)模型的来源分析显示，在所有季节都有很大的异质性。然而，该地区受到不同气溶胶类型的影响，人为细吸收气溶胶的丰度(86%)和沙尘颗粒的不可见率。此外，气溶胶体积尺寸分布(VSD)随气溶胶光学厚度的增大而增大，呈双峰对数正态结构，其中细模粒子的峰值比粗模粒子的峰值更为明显。此外，逆温产品在SSA中表现出强烈的光谱依赖性，并且在所有季节都具有很大的异质性。最后，圣巴巴拉DISORT大气辐射传输模式显示，由于气溶胶和−的显著差异，在SON(46.71W/m−2)和JJA(46.39W/m−2)期间，大气中的DARF更加明显，其年平均值为33.16W/m−2，对应的大气加热率为0.96K/d−1。该研究提供了关于SA西北部城市现有气溶胶分布及其对气候变化的潜在影响的信息，可为该地区的决策提供依据。
The present study focused on investigating the aerosol optical properties and direct aerosol radiative forcing (DARF) using the AERONET Sunphotometer measurements conducted during 2011–2017 over an urban-industrial city, Pretoria (25.75° S, 28.28° E) located in the Northwest of South Africa (SA). Results revealed high aerosol optical depth (AOD440) and Ångström exponent (AE440–870) during SON (0.28 ± 0.09, 1.46 ± 0.16) and DJF (0.24 ± 0.07, 1.48 ± 0.18) indicating the dominance of anthropogenic fine-mode aerosols from biomass burning. The single scattering albedo (SSA440) reached a maximum of 0.90 ± 0.05 in DJF and minimum (0.85 ± 0.04) during JJA. The source analysis from the concentration-weighted trajectory (CWT) model exhibited large heterogeneity in all seasons. However, the region is influenced by distinct aerosol types with the abundance of anthropogenic fine absorbing aerosols (86%) and the invisible ratio of dust particles. In addition, the aerosol volume size distribution (VSD) increased with an increasing AOD, exhibiting a bimodal lognormal structure, with a more pronounced peak in fine- relative to coarse-mode particles. Further, the inversion products showed a strong spectral dependence in SSA with substantial heterogeneity in all seasons. At last, the Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART) model showed that the DARF within the atmosphere was more pronounced during SON (46.71 W m−2) and JJA (46.39 W m−2) due to significant differences in AOD and SSA, with an annual mean value of 33.16 W m−2, and the corresponding atmospheric heating rate of 0.96 K day−1. The study provides information on the existing aerosol distribution and their potential impact on climatic change over an urban city in the Northwest of SA and could form a basis for policymaking over the region.