Columnar aerosol size distribution function obtained by inversion of spectral optical depth measurements for the Zanjan, Iran
Columnar aerosol size distribution function obtained by inversion of spectral optical depth measurements for the Zanjan, Iran
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DOI：
10.5194/amtd-3-2367-2010
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发表时间：
2010-05
期刊：
影响因子：
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通讯作者：
A. Masoumi;A. Bayat;H. Khalesifard
中科院分区：
文献类型：
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作者：
A. Masoumi;A. Bayat;H. Khalesifard
抽象的。我们正在报告伊朗西北部城市赞詹（北纬 36.70°，东经 48.51°）大气柱状气溶胶粒径分布函数的计算值。 2006年10月至2008年9月期间，使用Cimel CE318-2太阳光度计记录了赞詹大气在440 nm、670 nm、870 nm和1020 nm处的总光学深度的地面测量结果。通过从每个波长通道的总光学深度中减去分子光学深度，获得了光谱气溶胶光学深度。此外，当绘制气溶胶光学深度与波长对数的关系时，埃指数是通过对气溶胶光学深度的对数拟合来确定的。测量的气溶胶光学深度和埃指数值的每日平均值已在反演算法中实现，用于计算柱状气溶胶尺寸分布函数。在该算法中，气溶胶被视为不同大小且折射率为 1.45 的球体。我们发现，82% 的日子里，气溶胶处于粗模式。目前，超过 50% 的气溶胶体积浓度的半径 >1 μm。我们认为，这与赞詹的地理位置有关，该地区大部分干燥，经常遭受沙尘风袭击。
Abstract. We are reporting the calculated values of columnar aerosol size distribution function for atmosphere of Zanjan, a city in Northwest Iran (36.70° N, 48.51° E). Ground-based measurements of the total optical depth of the Zanjan atmosphere at 440 nm, 670 nm, 870 nm, and 1020 nm are recorded using a Cimel CE318-2 sunphotometer in the period of October 2006 to September 2008. The spectral aerosol optical depth has been obtained by subtraction of molecular optical depth from the total optical depth for each wavelength channel. Also the Angstrom exponent is determined by a logarithmic fit to the aerosol optical depth when it is plotted versus the logarithm of the wavelength. Daily averages of the measured aerosol optical depth and Angstrom exponent values have been implemented in an inversion algorithm for calculation of the columnar aerosol size distribution function. In this algorithm, the aerosols are considered as spheres of different size and refractive index of 1.45. We found that for 82% of the days, aerosols are in the coarse mode. For these days, more than 50% of the aerosol volume concentration has a radius >1 μm. We believe this is related to the geographical location of Zanjan in a mostly dry area and subject to frequent dust winds.