Investigating the nitrogen dioxide concentrations in the boundary layer by using multi-axis spectroscopic measurements and comparison with satellite observations
Investigating the nitrogen dioxide concentrations in the boundary layer by using multi-axis spectroscopic measurements and comparison with satellite observations
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DOI：
10.1007/s11356-016-7907-3
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发表时间：
2017-01-01
影响因子：
5.8
通讯作者：
Hakeem, Khalid Rehman
中科院分区：
文献类型：
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作者：
Khokhar, Muhammad Fahim;Nisar, Munazza;Hakeem, Khalid Rehman
这项研究的重点是在伊斯兰堡上空定期对二氧化氮（NO2）等化学活性痕量气体进行近地表观测。利用后向散射地外光源吸收光谱技术反演NO2差分斜柱密度（dSCD）。巴基斯坦伊斯兰堡国立科技大学环境科学与工程研究所（IESE）使用小型多轴差分光学吸收光谱（MAX-DOAS）仪器进行地基测量。对流层NO2垂直柱密度（VCD）是由实测的dSCD数据，采用几何空气质量因子方法反演的。进行了一项病例研究，以确定不同材料（用于覆盖手术工具的玻璃、有色玻璃和各种厚度的丙烯酸板）对dSCD回收的影响。发现厚度为5 mm的丙烯酸片材是最可行的外壳材料选择，因为其在可见光波长范围内表现出可忽略的影响。从地面微型MAX-DOAS测量得到的对流层NO2 VCD超过PakNEQS水平的两倍，并与巴基斯坦伊斯兰堡上空的卫星观测（均方根偏差为39%）进行了合理的比较（r（2）= 0.65，r = 0.81）。
This study emphasizes on near surface observation of chemically active trace gases such as nitrogen dioxide (NO2) over Islamabad on a regular basis. Absorption spectroscopy using backscattered extraterrestrial light source technique was used to retrieve NO2 differential slant column densities (dSCDs). Mini multi-axis-differential optical absorption spectroscopy (MAX-DOAS) instrument was used to perform ground-based measurements at Institute of Environmental Sciences and Engineering (IESE), National University of Sciences and Technology (NUST) Islamabad, Pakistan. Tropospheric vertical column densities (VCDs) of NO2 were derived from measured dSCDs by using geometric air mass factor approach. A case study was conducted to identify the impact of different materials (glass, tinted glass, and acrylic sheet of various thicknesses used to cover the instrument) on the retrieval of dSCDs. Acrylic sheet of thickness 5 mm was found most viable option for casing material as it exhibited negligible impact in the visible wavelength range. Tropospheric NO2 VCD derived from ground-based mini MAX-DOAS measurements exceeded two times the PakNEQS levels and showed a reasonable comparison (r(2) = 0.65, r = 0.81) with satellite observations (root mean square bias of 39 %) over Islamabad, Pakistan.