Polar stratospheric clouds (PSCs) play important roles in stratospheric ozone depletion during winter and spring at high latitudes (e.g., the Antarctic ozone hole). PSC particles provide sites for heterogeneous reactions that convert stable chlorine reservoir species to radicals that destroy ozone catalytically. PSCs also prolong ozone depletion by delaying chlorine deactivation through the removal of gas-phase HNO₃ and H₂O by sedimentation of large nitric acid trihydrate (NAT) and ice particles. Contemporary observations by the spaceborne instruments Michelson Interferometer for Passive Atmospheric Sounding (MIPAS), Microwave Limb Sounder (MLS), and Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) have provided an unprecedented polar vortex-wide climatological view of PSC occurrence and composition in both hemispheres. These data have spurred advances in our understanding of PSC formation and related dynamical processes, especially the firm evidence of widespread heterogeneous nucleation of both NAT and ice PSC particles, perhaps on nuclei of meteoritic origin. Heterogeneous chlorine activation appears to be well understood. Reaction coefficients on/in liquid droplets have been measured accurately, and while uncertainties remain for reactions on solid NAT and ice particles, they are considered relatively unimportant since under most conditions chlorine activation occurs on/in liquid droplets. There have been notable advances in the ability of chemical transport and chemistry-climate models to reproduce PSC temporal/spatial distributions and composition observed from space. Continued spaceborne PSC observations will facilitate further improvements in the representation of PSC processes in global models and enable more accurate projections of the evolution of polar ozone and the global ozone layer as climate changes.

中文翻译：

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极地平流层云：卫星观测、过程和臭氧消耗中的作用

极地平流层云 (PSC) 在高纬度地区（例如南极臭氧洞）的冬季和春季平流层臭氧消耗中发挥着重要作用。PSC 颗粒为异质反应提供场所，这些反应将稳定的氯储库物种转化为催化破坏臭氧的自由基。PSC 还通过去除气相 HNO ₃和 H ₂来延迟氯的失活，从而延长臭氧消耗O 通过大三水合硝酸 (NAT) 和冰粒的沉淀。用于被动大气探测的星载仪器迈克尔逊干涉仪 (MIPAS)、微波探臂仪 (MLS) 和具有正交极化的云气溶胶激光雷达 (CALIOP) 的当代观测提供了前所未有的极涡范围内 PSC 发生和组成的气候学观点。两个半球。这些数据促进了我们对 PSC 形成和相关动力学过程的理解的进步，尤其是 NAT 和冰 PSC 粒子广泛异质成核的有力证据，可能是在陨石起源的原子核上。多相氯活化似乎很容易理解。液滴上/液滴内的反应系数已被准确测量，虽然对固体 NAT 和冰颗粒的反应仍然存在不确定性，但它们被认为相对不重要，因为在大多数情况下，氯活化发生在液滴上/液滴中。化学传输和化学气候模型在重现从空间观察到的 PSC 时间/空间分布和组成的能力方面取得了显着进步。持续的星载 PSC 观测将有助于进一步改进全球模型中 PSC 过程的表示，并能够更准确地预测极地臭氧和全球臭氧层随气候变化的演变。化学传输和化学气候模型在重现从空间观察到的 PSC 时间/空间分布和组成的能力方面取得了显着进步。持续的星载 PSC 观测将有助于进一步改进全球模型中 PSC 过程的表示，并能够更准确地预测极地臭氧和全球臭氧层随气候变化的演变。化学传输和化学气候模型在重现从空间观察到的 PSC 时间/空间分布和组成的能力方面取得了显着进步。持续的星载 PSC 观测将有助于进一步改进全球模型中 PSC 过程的表示，并能够更准确地预测极地臭氧和全球臭氧层随气候变化的演变。