An Assessment of the Role of Natural and Anthropogenic CCN on Droplet Size Distributions in Marie Stratus in the North Atlantic

这项试验性野外试验将确定自然和人为云凝结核(CCN)的变化对加那利群岛海洋层状云滴尺寸分布的影响。需要检验的假设是，与自然海洋情况相比，来自欧洲和非洲的人为和自然气溶胶的运输导致CCN数量的增加，将导致系统地转向较小的液滴尺寸。尽管以前的工作表明，人为气溶胶影响了云微物理，但在个案研究中，尚未显示这种影响在全球范围内具有显著的气候学意义，也没有在偏远地区确定CCN的具体来源。为了证明污染气溶胶和云之间的相互作用正在改变气候的断言，即为了证明托米效应，有必要证明在背景条件下观察到的云滴尺寸分布的很大一部分变化是由污染产生的CCN引起的。这项实验将在加那利群岛的特内里费岛进行，在那里，自然和人为的CCN预计会有很大的变化，现有的AEROCE采样站位于计划进行ACE-2(气溶胶特性实验)的区域。海洋边界层云将在陆基高架基地附近进行采样。将使用PMS-CSASP-100-HV探头(直径2至95微米)连续监测液滴数量和尺寸分布，并将收集离散的液滴样本进行详细的化学分析。云-水化学将作为云前CCN化学成分的替代。人为和自然来源对液滴大小分布变化的相对影响将使用受体建模来确定。来自AEROCE Izania天文台(2600米)的气溶胶化学将与海洋层状云的云化学进行比较。

This pilot field experiment will determine the effects of variations in natural and anthropogenic cloud condensation nuclei (CCN) on marine stratus cloud droplet size distributions in the Canary Islands. The hypothesis to be tested is that increases in CCN numbers, caused by transport of anthropogenic and natural aerosols from Europe and Africa, contrasted to the natural marine situation, will cause a systematic shift to smaller droplet sizes. Although previous work has demonstrated that anthropogenic aerosols have affected cloud microphysics, in case studies, such effects have not been shown to be significant climatologically on a global scale, nor have specific sources of CCN been identified in a remote region. To justify the assertion that the interaction between pollution aerosols and clouds is altering climate, ie., to demonstrate the Twomey Effect, it is necessary to show that a significant portion of the observed variance of the cloud droplet size distribution under background conditions is caused by pollution-derived CCN. This experiment will be conducted at Tenerife in the Canary Islands, where wide variations in natural and anthropogenic CCN are expected, where an existing AEROCE sampling station is located, in the region where the ACE-2 (Aerosol Characterization Experiment) is planned. Marine boundary-layer stratus clouds will be sampled near could base at a ground-based, elevated site. The droplet number and size distribution will be monitored continuously using a PMS- CSASP-100-HV probe (2 to 95 um dia.), and discrete droplet samples will be collected for detailed chemical analysis. The cloud-water chemistry will be used as a surrogate for the chemical composition of the pre-cloud CCN. The relative effects of anthropogenic and natural sources on variations in droplet size distributions will be identified using receptor modeling. Aerosol chemistry from the AEROCE Izania Observatory (2600m) will be compared with the cloud chemistry of m arine stratus.