Particulate Matter Airborne Sampling Inlet Experiment

在许多方面，科学家对大气气体的行为比气溶胶了解得多。均相气相化学本质上比涉及多个相的化学简单。然而，气溶胶的非均相化学对于理解大气化学中的几个重要问题至关重要。人类的一些活动可能会对气候产生影响，因为它们产生的气溶胶会改变地球的反照率。这些气溶胶也可能影响水蒸气在云中凝结的趋势，改变它们的液滴大小分布、空间范围、沉淀趋势和光学性质。自然云量可能在一定程度上受到清洁地区气溶胶可用性的控制。限制我们对气溶胶化学的理解的因素之一是很难从机载平台上取样。虽然许多空气实验测量了大气中的气溶胶种类，但用于将空气样本带入收集系统的入口存在潜在的采样问题。例如，采样入口的惯性和电泳过程有可能去除过滤器上游的一些气溶胶。在某些情况下，损失可能超过50%。在颗粒物空气采样入口实验中，气溶胶将与NCAR的Electra上的各种进气系统同时采样，以确定哪些参数（流雷诺数、斯托克斯数、曲率半径、表面涂层、气溶胶直径等）控制这些损失。最终目标是开发最无伪影的采样系统，以便从飞机上收集气溶胶。

In many respect, scientist understand the behavior of atmospheric gases much better than that of aerosols. Homogeneous gas-phase chemistry is inherently simpler than that which involves more than one phase. Yet the heterogeneous chemistry of aerosols is central to understanding several of the important problems in atmospheric chemistry. Some of man's activities may have an impact on climate because they create aerosols which alter the Earth's albedo. These aerosols may also affect the tendency of water vapor to condense in clouds, altering their droplet size-distribution, spatial extent, tendency to precipitate, and optical properties. Natural cloudiness may be controlled in part by the availability of aerosols in clean regions. One of the factors which limits our understanding of aerosol chemistry is the difficulty of sampling them from airborne platforms. Although many airborne experiments have measured aerosol species in the atmospheric, there are potential sampling problems with the inlets used to bring air samples into collection systems. Inertial and electrophoretic processes in sampling inlets have the potential to remove some aerosols upstream of a filter, for instance. Losses can exceed 50% in some cases. In the Particulate matter Airborne Sampling INlet experiment aerosols will be sampled simultaneously with a variety of intake systems aboard NCAR's Electra, to determine which parameters (flow Reynolds number, Stokes number, redius of curvature, surface coating, aerosol diameter, etc.) control these losses. The ultimate goal is the development of the most artifact-free sampling system possible for collecting aerosols from aircraft.