Characteristics of Cloud-Nucleating Aerosols and Their Effects on Cloud Microphysical and Radiative Properties in INDOEX

该项目旨在了解气溶胶粒子如何通过改变液滴数量、浓度和大小影响云的辐射特性（所谓的“间接”效应）。 它将利用印度洋实验期间用机载仪器获得的气溶胶物理和化学特性观测结果。 光学粒子计数器、云凝结核谱仪和电子显微镜分析是分析气溶胶性质的主要手段。 在云下和云上取样的粒子的特性将与从云滴中提取的残留核进行比较，以评估哪些粒子充当云凝结核。 特别是，硫酸盐，海盐，土壤粉尘和元素碳的相对重要性将进行评估。 同时，还比较了周围粒子和剩余核的临界过饱和谱。 通过一系列案例研究，主要研究者将确定云中气溶胶是否遵循预期的简单绝热关系，即具有最低临界过饱和度的粒子优先成核云滴。 空气轨迹和气溶胶化学测量将用于确定人为气溶胶在影响云特性方面的具体作用。 将通过多变量技术研究热力学、气溶胶、微物理和云辐射参数的变化，以确定参数依赖性，并帮助将气溶胶效应与云的动力效应分开。 对该项目的支助由大气化学和物理气象学方案以及全球变化方案的水和能源：大气、植被和地球相互作用倡议共同提供。

This project is aimed at understanding how aerosol particles affect cloud radiative properties through changes in droplet number concentration and size (the so-called "indirect" effect). It will employ observations of the physical and chemical properties of aerosols obtained with airborne instruments during the Indian Ocean Experiment (INDOEX). Optical particle counters, cloud condensation nucleus spectrometers, and electron microscope analysis are the principal means of analyzing the aerosol properties. Characteristics of particles sampled both below and above clouds will be compared with residual nuclei extracted from cloud droplets to assess which particles act as cloud condensation nuclei. In particular, the relative importance of sulfate, sea-salt, soil-dust, and elemental carbon will be evaluated. The critical supersaturation spectra of the ambient particles and residual nuclei will be compared as well. Through a series of case studies, the principal investigator will determine whether in-cloud aerosol follow an expected simple adiabatic relationship, that is, the particles with the lowest critical supersaturation preferentially nucleate cloud droplets. Air trajectories and aerosol chemical measurements will be used to determine the specific role of anthropogenic aerosols in affecting cloud properties. Variations in thermodynamic, aerosol, microphysical, and cloud radiative parameters will be studied via multivariate techniques in order to ascertain parameter dependence and to help separate aerosol effects from dynamic effects on clouds. Support for this project is shared by the Atmospheric Chemistry and Physical Meteorology Programs and the Water and Energy: Atmospheric, Vegetative and Earth Interactions (WEAVE) Initiative of the Global Change Program.