Study of Stratospheric Aerosols and Their Heterogeneous Effects on Ozone

平流层中的细颗粒物阻碍太阳辐射到达地球表面。空气中粒子的大小、形状和化学成分决定了不同波长的光在吸收或散射过程中衰减的程度。因此，要想预测这些平流层气溶胶对大气热平衡的影响，或对地球表面变暖或变冷效应的影响，就需要了解它们的高度分布、它们的物理和化学特性以及它们的时空变化。由于对南极臭氧空洞的研究，粒子在平流层化学中的作用也得到了更充分的认识。气溶胶分布的一些基线水平是未受干扰的平流层的特征，但火山喷发会在不可预测的时间和地点注入气体和火山灰颗粒，而且数量相当大。对火山或其他自然影响的长期或偶然性影响的评估需要获得长时间序列的观测资料。从七十年代到现在，这项拨款的主要研究人员一直在定期进行一系列仪器气球飞行，以测量平流层气溶胶的大小分布和高度分布。这个观测项目提供了唯一可用的一组基于在平流层进行的仪器测量的数据。在怀俄明的拉勒米已经安装了仪器气球系统，能够表征1982年爆发的墨西哥埃尔奇雄火山羽流中的气溶胶。该项目将继续这一重要的平流层颗粒记录，并提高颗粒的尺寸分辨率。平流层气溶胶目前似乎处于背景水平，但在重大火山爆发来临之际，该项目将重点确定与颗粒的非均相反应有关的臭氧损耗。在高纬度地区（瑞典基律纳）进行测量的目的是确定极地平流层云的颗粒大小分布，这种云被认为有助于在南极洲观测到的臭氧消耗。

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.