Measurement of Marine Cloud Droplet Size Distributions and Analysis of Relationships to Chemical Fluxes, CCN Concentration, and Boundary Layer Physics

研究人员计划在华盛顿州西北海岸的一个海洋站点进行云滴大小光谱和液态水含量（LWC）的光学测量，同时测量云和雨水组成、气溶胶大小光谱和三维风。通过将液滴光谱和LWC与其他测量相结合，研究人员将解决以下两个问题：1)与植被拦截云水相关的液滴和化学涡流通量；2)海洋边界层中液滴与CCN数浓度之间的关系。云滴与云凝结核（CCN）的关系将通过比较晴空中的CCN浓度（从气溶胶大小光谱推断）与云滴浓度来研究。垂直风速、LWC和液滴浓度将结合起来产生综合云液滴通量的涡动相关估计和液滴沉积速度的大小依赖性。测量的云水涡流通量将与计算的水滴沉降通量和人工树的云水拦截量进行比较。与雨有关的化学通量将与拦截云水有关的化学通量进行比较。了解微滴/化学通量和CCN/微滴关系，对于表征大气与生物圈间痕量物种的化学循环，以及了解气候对海洋大气CCN循环的响应具有重要意义。

The investigator plans to make optical measurements of cloud droplet size spectra and liquid water content (LWC) with simultaneous measurements of cloud and rain water composition, aerosol size spectra, and three dimensional winds at a marine site on the NW coast of Washington State. By combining the droplet spectra and LWC with the other measurement the investigators will address both: 1) droplet and chemical eddy fluxes associated with interception of cloud water by vegetation and 2) the relationship between droplet and CCN number concentration in the marine boundary layer. Cloud droplet- cloud condensation nuclei (CCN) relationships will be studied by comparing CCN concentrations (inferred from aerosol size spectra) in clear air to cloud droplet concentrations. Vertical wind speed, LWC, and droplet concentration will be combined to produce eddy covariance estimates of integrated cloud droplet fluxes and the size dependence of droplet deposition velocity. The measured cloud water eddy fluxes will be compared to calculated droplet sedimentation fluxes and cloud water interception by an artificial tree. The chemical fluxes associated with rain will be compared to those associated with intercepted cloud water. Understanding droplet/chemical flux and CCN/droplet relationships is important for characterizing the chemical cycling of trace species between the atmosphere and the biosphere and for understanding the response of climate to CCN cycling in the marine atmospheric.