Identification of aerosol types over Indo-Gangetic Basin: implications to optical properties and associated radiative forcing
Identification of aerosol types over Indo-Gangetic Basin: implications to optical properties and associated radiative forcing
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DOI：
10.1007/s11356-015-4495-6
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发表时间：
2015-04
影响因子：
5.8
通讯作者：
S. Tiwari;A. Srivastava;Ashutosh Kumar Singh;Sachchidanand Singh
中科院分区：
文献类型：
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作者：
S. Tiwari;A. Srivastava;Ashutosh Kumar Singh;Sachchidanand Singh
印度恒河盆地(IGB)的气溶胶是硫酸盐、尘埃、黑碳和其他可溶和不溶组分的混合物。不仅要确定这些不同的气溶胶类型，而且要评估这些组分的光学和辐射影响，这不仅是一项挑战。在本研究中，使用了精细模式分数和单次散射反照率的适当阈值来首先确定IGB上空的气溶胶类型。四种主要的气溶胶类型可被识别为污染尘埃(PD)、污染大陆(PC)、富碳黑(BCE)和富含有机碳(OCE)。此外，还研究了这些不同类型的气溶胶对光学性质和辐射强迫的影响。根据美国NASA气溶胶机器人网络计划部署的CIMEL太阳/天空辐射计测量得出的气溶胶产品来自分布在巴基斯坦和印度北部的卡拉奇、拉合尔、斋浦尔和坎普尔四个不同的地点。在卡拉奇和斋浦尔，PD是最主要的气溶胶类型，占所有气溶胶类型的50%以上。另一方面，OCE在所有车站只贡献了大约12%-15%，除了坎普尔，它对∼的贡献是38%。对于PD气溶胶类型，气溶胶光学厚度的光谱依赖性相对较低，其AE值最低(<；0.5)；而对于其余气溶胶类型，AOD的光谱依赖性较大，其AE值最高(>；1.0)。研究发现，OCE(>；0.9)型气溶胶的SSA最高，而BCE(<；0.9)型气溶胶的SSA最低，光谱变异性差异很大。在IGB的所有四个站中，在拉合尔发现地面和大气中的直接气溶胶辐射强迫最大。
The aerosols in the Indo-Gangetic Basin (IGB) are a mixture of sulfate, dust, black carbon, and other soluble and insoluble components. It is a challenge not only to identify these various aerosol types, but also to assess the optical and radiative implications of these components. In the present study, appropriate thresholds for fine-mode fraction and single-scattering albedo have been used to first identify the aerosol types over IGB. Four major aerosol types may be identified as polluted dust (PD), polluted continental (PC), black carbon-enriched (BCE), and organic carbon-enriched (OCE). Further, the implications of these different types of aerosols on optical properties and radiative forcing have been studied. The aerosol products derived from CIMEL sun/sky radiometer measurements, deployed under Aerosol Robotic Network program of NASA, USA were used from four different sites Karachi, Lahore, Jaipur, and Kanpur, spread over Pakistan and Northern India. PD is the most dominant aerosol type at Karachi and Jaipur, contributing more than 50 % of all the aerosol types. OCE, on the other hand, contributes only about 12–15 % at all the stations except at Kanpur where its contribution is ∼38 %. The spectral dependence of AOD was relatively low for PD aerosol type, with the lowest AE values (<0.5); whereas, large spectral dependence in AOD was observed for the remaining aerosol types, with the highest AE values (>1.0). SSA was found to be the highest for OCE (>0.9) and the lowest for BCE (<0.9) type aerosols, with drastically different spectral variability. The direct aerosol radiative forcing at the surface and in the atmosphere was found to be the maximum at Lahore among all the four stations in the IGB.