Seasonal variations of the physical and optical characteristics of Saharan dust: Results from the Dust Outflow and Deposition to the Ocean (DODO) experiment
Seasonal variations of the physical and optical characteristics of Saharan dust: Results from the Dust Outflow and Deposition to the Ocean (DODO) experiment
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DOI：
10.1029/2007jd009606
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发表时间：
2008-07
影响因子：
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通讯作者：
C. McConnell;E. Highwood;H. Coe;P. Formenti;B. Anderson;S. Osborne;S. Nava;K. Desboeufs;Gao Chen;M. Harrison
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文献类型：
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作者：
C. McConnell;E. Highwood;H. Coe;P. Formenti;B. Anderson;S. Osborne;S. Nava;K. Desboeufs;Gao Chen;M. Harrison
[1]通过其对太阳和陆地辐射的直接传统效应及其在地球化学系统中的作用，北非对气候非常重要。尘埃流出和沉积到海洋项目（DODO）旨在描述两个季节中北非空气尘埃的物理和光学特性，并使用这些观测结果来约束模型模拟，最终目标是能够量化铁在北大西洋的沉积。现场属性的灰尘从空气中的运动测量在2006年2月和8月，在塞内加尔达喀尔，在这里。单次散射平均值（0.99，0.98），质量比消光（0.85 m2 g·1，1.14 m2 g·1），不对称参数（0.68，0.68），以及折射率（1.53-0.0005i，1.53-0.0014i），干、湿两季有不同程度的差异。据推测，这些差异是由于不同的源区和运输过程，也不同的DODO运动之间。元素比的Ca/Al被认为是不同的旱季和雨季（1.1和0.5，分别）。不同季节之间以及陆地和海洋位置之间的垂直剖面存在差异，反映了季节的不同动态。使用测量的粗模式的大小分布和说明米氏计算，光学性质被发现是非常敏感的存在和数量的粗模式的矿物粉尘，和精确测量的重要性粗模式的灰尘被突出。
[1] NorthAfricandustisimportantforclimatethroughitsdirectradiativeeffectonsolarand terrestrial radiation and its role in the biogeochemical system. The Dust Outflow and Deposition to the Ocean project (DODO) aimed to characterize the physical and optical properties of airborne North African dust in two seasons and to use these observations to constrainmodelsimulations,withtheultimateaimofbeingabletoquantifythedepositionof iron to the North Atlantic Ocean. The in situ properties of dust from airborne campaigns measured during February and August 2006, based at Dakar, Senegal, are presented here. Average values of the single scattering albedo (0.99, 0.98), mass specific extinction (0.85 m 2 g � 1 ,1 .14 m 2 g � 1 ), asymmetry parameter (0.68, 0.68), and refractive index (1.53–0.0005i, 1.53–0.0014i) for the accumulation mode were found to differ by varying degrees between the dry and wet season, respectively. It is hypothesized that these differences are due to different source regions and transport processes which also differ between the DODO campaigns. Elemental ratios of Ca/Al were found to differ between the dry and wet season (1.1 and 0.5, respectively). Differences in vertical profiles are found between seasons and between land and ocean locations and reflect the different dynamics of the seasons. Using measurements of the coarse mode size distribution and illustrative Mie calculations, the optical properties are found to be very sensitive to the presence and amount of coarse mode of mineral dust, and the importance of accurate measurements of the coarse mode of dust is highlighted.