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OBSERVATIONAL EVIDENCE FOR CHEMICAL OZONE DEPLETION OVER THE ARCTIC IN WINTER 1991-92

机译：1991-92年冬季北极上空化学臭氧消耗的观测证据

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LONG-TERM depletion of ozone has been observed since the early 1980s in the Antarctic polar vortex, and more recently at midlatitudes in both hemispheres, with most of the ozone loss occurring in the lower stratosphere(1). Insufficient measurements of ozone exist, however, to determine decadal trends in ozone concentration in the Arctic winter. Several studies of ozone concentrations in the Arctic vortex have inferred that chemical ozone loss has occurred(2-11); but because natural variations in ozone concentration at any given location can be large, deducing long-term trends from time series is fraught with difficulties. The approaches used previously have often been indirect, typically relying on relationships between ozone and long-lived tracers. Most recently Manney et al.(11) used such an approach, based on satellite measurements, to conclude that the observed ozone decrease of about 20% in the lower stratosphere in February and March 1993 was caused by chemical, rather than dynamical, processes. Here we report the results of a new approach to calculate chemical ozone destruction rates that allows us to compare ozone concentrations in specific air parcels at different times, thus avoiding the need to make assumptions about ozone/tracer ratios. For the Arctic vortex of the 1991-92 winter we find that, at 20 km altitude, chemical ozone loss occurred only between early January and mid February and that the loss is proportional to the exposure to sunlight. The timing and magnitude are broadly consistent with existing understanding of photochemical ozone-depletion processes. [References: 32]
机译：自1980年代初以来，南极极涡中就出现了臭氧的长期耗竭现象，最近在两个半球的中纬度地区都出现了臭氧耗损现象，其中大部分臭氧流失发生在平流层下部（1）。但是，臭氧测量值不足，无法确定北极冬季臭氧浓度的年代际变化趋势。对北极涡流中臭氧浓度的几项研究推断出化学臭氧的损失已经发生（2-11）。但是由于任何给定位置的臭氧浓度的自然变化都可能很大，因此很难从时间序列中推断出长期趋势。以前使用的方法通常是间接的，通常依赖于臭氧和长寿命示踪剂之间的关系。最近，Manney等人（11）基于卫星测量结果使用了这种方法，得出的结论是，1993年2月和3月在平流层下部观测到的臭氧减少量约为20％，这是化学过程而非动力过程引起的。在这里，我们报告了一种计算化学臭氧破坏率的新方法的结果，该方法使我们能够在不同时间比较特定空气包裹中的臭氧浓度，从而避免了对臭氧/示踪剂比率进行假设的需要。对于1991-92年冬季的北极涡流，我们发现在20 km的海拔高度，化学臭氧损失仅在1月初至2月中旬之间发生，并且该损失与日照成正比。时间和量级与对光化学臭氧消耗过程的现有理解大致一致。 [参考：32]

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