Study of Stratospheric Aerosols and Their Heterogeneous Effects on Ozone

平流层中的细小颗粒物阻碍了太阳辐射到达地球表面。空气中颗粒物的大小、形状和化学成分决定了不同波长的光被吸收或散射过程衰减的程度。因此，需要了解这些平流层气溶胶的海拔分布、它们的物理和化学特性以及它们的空间和时间变化，以便努力预测它们对大气热平衡的影响，或对地球表面变暖或变冷的影响。随着对南极臭氧层空洞的研究，粒子对平流层化学的作用也得到了更充分的认识。一些基线水平的气溶胶分布是未受干扰的平流层的特征，但火山喷发在不可预测的时间和地点以相当大的数量注入气体和火山灰颗粒。对火山或其他自然影响的长期或间歇性影响的评估需要获得长时间的观察序列。在整个七十年代到目前为止，这笔赠款的主要调查人员定期进行一系列仪表式气球飞行，以测量平流层气溶胶的尺寸分布和高度分布。这一观测计划提供了基于在平流层进行的仪器测量的唯一可用的数据集。已经安装在怀俄明州拉勒米的仪表式气球系统能够识别1982年喷发的墨西哥火山El Chichon羽流中的气溶胶。该项目将继续保持平流层颗粒的这一重要记录，改进颗粒的尺寸分辨率。平流层气溶胶目前似乎处于背景水平，但随着一次重大火山喷发的到来，该项目将侧重于确定与颗粒上的非均相反应有关的臭氧消耗。在高纬度(瑞典基律纳)进行测量的目的是确定极地平流层云的粒度分布，如在南极洲观察到的那样，极地平流层云被认为有助于臭氧消耗。

Fine particulate matter in the stratosphere impedes the passage of solar radiation to the earth's surface. The size, shape, and chemical composition of airborne particles determine the extent to which different wavelengths of light are attenuated by processes of absorption or scattering. Therefore, knowledge of the altitude profiles of these stratospheric aerosols, of their physical and chemical characteristics, and of their spatial and temporal changes, is required in any effort to predict their effects on the heat balance of the atmosphere, or on warming or cooling effects at the earth's surface. As a result of study on the Antarctic ozone hole, the role of particles on the chemistry of the stratosphere is also being more fully appreciated. Some baseline level of aerosol distribution characterizes the undisturbed stratosphere, but volcanic eruptions inject gases and ash particles at unpredictable times and places and in quite significant amounts. An assessment of either long- term or episodic effects of volcanoes or other natural influences requires the acquisition of a long time series of observation. Through the decade of the seventies and up to the present, the principal investigators of this grant have maintained a regular series of instrumented balloon flights to measure the size distributions and altitude profiles of stratospheric aerosols. This observational program has provided the only available set of data based on instrumental measurements made in the stratosphere. The instrumented balloon system already in place at Laramie, Wyoming, was able to characterize aerosols in the plume of El Chichon, a Mexican volcano that erupted in 1982. This project will continue this important record of stratospheric particulate with improvements in the size resolution of the particles. The stratospheric aerosol presently appears to be at background levels, but in the advent of a major volcanic eruption, the project will focus on identifying any depletion in ozone associated with heterogeneous reactions on the particles. Measurements at high latitude (Kiruna, Sweden), are aimed a determining the particle size distribution of polar stratospheric clouds which are thought to be instrumental in ozone depletion as observed in Antarctica.