Measurements of the relation between aerosol properties and microphysics and chemistry of low level liquid water clouds in Northern Finland
Measurements of the relation between aerosol properties and microphysics and chemistry of low level liquid water clouds in Northern Finland
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芬兰北部低层液态水云气溶胶特性与微物理和化学之间关系的测量
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
Y. Viisanen
中科院分区：
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作者：
H. Lihavainen;V. Kerminen;M. Komppula;A. Hyvärinen;J. Laakia;S. Saarikoski;U. Makkonen;N. Kivekäs;R. Hillamo;M. Kulmala;Y. Viisanen
2004年10月20日至11月9日在芬兰北方进行的第一次帕拉斯云实验（第一步）期间，对边界层云的物理和化学特性以及相关的气溶胶特性进行了研究。测量中使用了两个相距6公里、海拔不同的观测站。低空观测站总是在云层之下，而高空观测站在活动期间大约75%的时间都在云层之内。云滴种群的直接测量表明，我们早期的方法，确定云滴残留颗粒尺寸分布和相应的激活分数使用连续的气溶胶数量尺寸分布测量在两个站是有效的，只要云事件被仔细筛选，以排除降水云，并确保相同的空气质量已被测量在两个站。我们观察到，一个不可忽略的部分云滴起源于艾特肯模式粒子，即使在中度污染的空气质量。我们发现了气溶胶对云的第一个间接影响的明确证据，但也表明，对于这种类型的云，云滴数浓度和气溶胶粒子数浓度之间不存在简单的关系。气溶胶粒子的化学成分主要是颗粒有机物（POM）和硫酸盐在大陆气团和POM，钠和氯在海洋气团。云水的无机组成与气溶胶相的无机组成相似，不受无机微量气体的影响。
Physical and chemical properties of boundary layer clouds, together with relevant aerosol properties, were investigated during the first Pallas Cloud Experiment (First Pace) conducted in northern Finland between 20 October and 9 November 2004. Two stations located 6 km apart from each other at different altitudes were employed in measurements. The low-altitude station was always below the cloud layer, whereas the high-altitude station was inside clouds about 75% of the time during the campaign. Direct measurements of cloud droplet populations showed that our earlier approach of determining cloud droplet residual particle size distributions and corresponding activated fractions using continuous aerosol number size distribution measurements at the two stations is valid, as long as the cloud events are carefully screened to exclude precipitating clouds and to make sure the same air mass has been measured at both stations. We observed that a non-negligible fraction of cloud droplets originated from Aitken mode particles even at moderately-polluted air masses. We found clear evidence on first indirect aerosol effect on clouds but demonstrated also that no simple relation between the cloud droplet number concentration and aerosol particle number concentration exists for this type of clouds. The chemical composition of aerosol particles was dominated by particulate organic matter (POM) and sulphate in continental air masses and POM, sodium and chlorine in marine air masses. The inorganic composition of cloud water behaved similarly to that of the aerosol phase and was not influenced by inorganic trace gases.