Observations of aerosols in the free troposphere and marine boundary layer of the subtropical Northeast Atlantic: Discussion of processes determining their size distribution
Observations of aerosols in the free troposphere and marine boundary layer of the subtropical Northeast Atlantic: Discussion of processes determining their size distribution
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副热带东北大西洋自由对流层和海洋边界层气溶胶的观测：讨论决定其尺寸分布的过程
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发表时间：
1997
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影响因子：
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通讯作者：
J. Prospero
中科院分区：
文献类型：
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作者：
F. Raes;R. Dingenen;E. Cuevas;P. Velthoven;J. Prospero
1994年7月期间，在加那利群岛特内里费岛的两个地点测量了亚微米气溶胶粒径分布。一个站位于自由对流层（FT），另一个位于海洋边界层（MBL）。运输对这两个网站是强烈解耦：FT首先受到来自北非平流的灰尘和含硫酸盐的空气质量，后来由清洁的空气质量起源于北大西洋，而MBL总是受到东北信风环流。在FT的亚微米气溶胶分布主要是单峰的几何平均直径为120 nm和55 nm，在多尘和清洁的条件下，分别。在清洁条件下相对较小的直径表明，气溶胶起源于对流层上部，而不是在大陆地区或平流层下部。在多尘条件下，亚微米气溶胶的物理和化学性质表明，它有一个人为的起源在南欧，它仍然在很大程度上与超微米矿物尘埃颗粒在北非到特内里费岛的运输过程中外部混合。除了天气的变化，在FT站点观察到的气溶胶粒径分布的强烈的日变化，其特征在于由一个强大的白天模式的超细颗粒。这被解释为是在上坡风，这是人为和生物源排放在岛上扰动的光致成核的结果。未发现在未受干扰的FT中发生成核的证据。在测量期间，MBL站点没有受到欧洲污染的强烈影响。MBL气溶胶粒径分布呈双峰型，但Aitken的相对浓度和累积模式变化很大。积累模式可以与云处理的艾特肯模式，但也污染气溶胶，这是平流内的MBL或夹带从FT。在MBL内没有观察到成核的爆发。
During July 1994, submicron aerosol size distributions were measured at two sites on Tenerife, Canary Islands. One station was located in the free troposphere (FT), the other in the marine boundary layer (MBL). Transport toward these two sites was strongly decoupled: the FT was first affected by dust and sulfate-laden air masses advecting from North Africa and later by clean air masses originating over the North Atlantic, whereas the MBL was always subject to the northeasterly trade wind circulation. In the FT the submicron aerosol distribution was predominantly monomodal with a geometric mean diameter of 120 nm and 55 nm during dusty and clean conditions, respectively. The relatively small diameter during the clean conditions indicates that the aerosol originated in the upper troposphere rather than over continental areas or in the lower stratosphere. During dusty conditions the physical and chemical properties of the submicron aerosol suggest that it has an anthropogenic origin over southern Europe and that it remains largely externally mixed with the supermicron mineral dust particles during its transport over North Africa to Tenerife. Apart from synoptic variations, a strong diurnal variation in the aerosol size distribution is observed at the FT site, characterized by a strong daytime mode of ultrafine particles. This is interpreted as being the result of photoinduced nucleation in the upslope winds, which are perturbed by anthropogenic and biogenic emissions on the island. No evidence was found for nucleation occurring in the undisturbed FT. The MBL site was not strongly affected by European pollution during the period of the measurements. The MBL aerosol size distribution was bimodal, but the relative concentration of Aitken and accumulation mode varied strongly. The accumulation mode can be related to cloud processing of the Aitken mode but also to pollution aerosol which was advected within the MBL or entrained from the FT. No bursts of nucleation were observed within the MBL.