DataSheet2_Evolution of total column ozone prior to the era of ozone depletion.PDF

Total column ozone has been monitored for almost a century. The focus of most research studies over the last 40 years was on the era of ozone depletion and the detection of signs of recovery. However, the question also arises to what extent total column ozone has changed prior to this era. Possible causes could be changes in ozone production (both in the troposphere and stratosphere) due to changing atmospheric composition, changes in solar activity, or climatic changes. In this contribution, I discuss the evolution of total column ozone in the 40 years from 1924, when ozone monitoring started, to 1963, which is approximately the time when ozone depletion started to affect the ozone layer. Using long historical measurements, as well as an assimilated zonal mean total column ozone dataset, I show that variability was characterized by strong interannual-to-multiannual anomalies, with a small positive trend at the northern mid-to high-latitudes of ca. 6 DU over the 40-year period. The latitudinal pattern of the trend matches that found in CMIP6 models, but the trend at mid-latitudes is weaker than that in the models.

总柱臭氧（total column ozone）的监测工作已开展近一个世纪。过去40年间的多数研究均聚焦于臭氧损耗时代以及臭氧恢复迹象的探测。然而，学界也不禁发问：在该时代之前，总柱臭氧发生了多大程度的变化？其潜在成因可能包括：大气成分变化引发的对流层与平流层臭氧生成量改变、太阳活动变化，或是气候变迁。本文探讨了1924年（臭氧监测启动之年）至1963年这40年间的总柱臭氧变化历程，而1963年大致是臭氧损耗开始波及臭氧层的时间节点。本文借助长期历史观测数据以及一套经同化处理的纬向平均总柱臭氧数据集，证实该时段臭氧变化以显著的年际至多年际异常为主要特征，且在北半球中高纬度地区呈现约6多布森单位（Dobson Unit，DU）的微弱正趋势，该趋势覆盖上述40年周期。该趋势的纬度分布格局与耦合模式比较计划第六阶段（CMIP6）的模式结果一致，但中纬度地区的趋势强度弱于模式模拟结果。