Abstract. The long-term record of Umkehr measurements from four NOAA Dobson spectrophotometers was reprocessed after updates to the instrument calibration procedures. In addition, a new data quality-control tool was developed for the Dobson automation software (WinDobson). This paper presents a comparison of Dobson Umkehr ozone profiles from NOAA ozone network stations (Boulder, OHP, MLO, Lauder) against several satellite records, including Aura Microwave Limb Sounder (MLS; ver. 4.2), and combined SBUV and OMPS records (NASA AGG and NOAA COH). A subset of satellite data is selected to match Dobson Umkehr observations at each station spatially (distance less than 200 km) and temporally (within 24 hours). Umkehr Averaging Kernels (AKs) are applied to vertically smooth all overpass satellite profiles prior to comparisons. The station Umkehr record consists of several instrumental records, which have different optical characterizations, and thus instrument-specific stray light contributes to the data processing errors and creates step changes in the record. This work evaluates the overall quality of Umkehr long-term measurements at NOAA ground-based stations and assesses the impact of the instrumental changes on the stability of the Umkehr ozone profile record. This paper describes a method designed to correct biases and discontinuities in the retrieved Umkehr profile that originate from the Dobson calibration process, repair, or optical realignment of the instrument. The M2GMI and GMI CTM ozone profile model output matched to station location and date of observation is used to evaluate instrumental step changes in the Umkehr record. Homogenization of the Umkehr record and discussion of the apparent stray light error in retrieved ozone profiles are the focus of this paper. Homogenization of ground-based records is of great importance for studies of long-term ozone trends and climate change.

中文翻译：

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用于臭氧趋势分析的优化 Umkehr 剖面算法

摘要。在更新仪器校准程序后，重新处理了来自四台 NOAA Dobson 分光光度计的 Umkehr 测量结果的长期记录。此外，还为 Dobson 自动化软件 (WinDobson) 开发了一种新的数据质量控制工具。本文介绍了来自 NOAA 臭氧网络站（博尔德、OHP、MLO、Lauder）的 Dobson Umkehr 臭氧剖面与几个卫星记录的比较，包括 Aura 微波肢体测深仪（MLS；版本 4.2），以及 SBUV 和 OMPS 组合记录（美国宇航局） AGG 和 NOAA COH）。选择卫星数据的子集以在空间（距离小于 200 公里）和时间（24 小时内）上匹配每个站点的 Dobson Umkehr 观测。在比较之前，应用 Umkehr 平均内核 (AK) 来垂直平滑所有立交卫星剖面。台站 Umkehr 记录由几个仪器记录组成，它们具有不同的光学特征，因此仪器特定的杂散光会导致数据处理错误并在记录中产生阶跃变化。这项工作评估了 NOAA 地面站 Umkehr 长期测量的整体质量，并评估了仪器变化对 Umkehr 臭氧剖面记录稳定性的影响。本文介绍了一种方法，旨在纠正检索到的 Umkehr 剖面中的偏差和不连续性，这些偏差和不连续性源于仪器的 Dobson 校准过程、维修或光学重新对准。与站点位置和观测日期匹配的 M2GMI 和 GMI CTM 臭氧剖面模型输出用于评估 Umkehr 记录中的仪器阶跃变化。Umkehr 记录的均质化和对检索到的臭氧剖面中明显杂散光误差的讨论是本文的重点。地面记录的均一化对于长期臭氧趋势和气候变化的研究非常重要。