We report the recovery and processing methodology of the first ever multi-year lidar dataset of the stratospheric aerosol layer. A Q-switched ruby lidar measured 66 vertical profiles of 694 nm attenuated backscatter at Lexington, Massachusetts, between January 1964 and August 1965, with an additional nine profile measurements conducted from College, Alaska, during July and August 1964. We describe the processing of the recovered lidar backscattering ratio profiles to produce mid-visible (532 nm) stratospheric aerosol extinction profiles (sAEP₅₃₂) and stratospheric aerosol optical depth (sAOD₅₃₂) measurements, utilizing a number of contemporary measurements of several different atmospheric variables. Stratospheric soundings of temperature and pressure generate an accurate local molecular backscattering profile, with nearby ozone soundings determining the ozone absorption, which are used to correct for two-way ozone transmittance. Two-way aerosol transmittance corrections are also applied based on nearby observations of total aerosol optical depth (across the troposphere and stratosphere) from sun photometer measurements. We show that accounting for these two-way transmittance effects substantially increases the magnitude of the 1964/1965 stratospheric aerosol layer's optical thickness in the Northern Hemisphere mid-latitudes, then ∼ 50 % larger than represented in the Coupled Model Intercomparison Project 6 (CMIP6) volcanic forcing dataset. Compared to the uncorrected dataset, the combined transmittance correction increases the sAOD₅₃₂ by up to 66 % for Lexington and up to 27 % for Fairbanks, as well as individual sAEP₅₃₂ adjustments of similar magnitude. Comparisons with the few contemporary measurements available show better agreement with the corrected two-way transmittance values.Within the January 1964 to August 1965 measurement time span, the corrected Lexington sAOD₅₃₂ time series is substantially above 0.05 in three distinct periods, October 1964, March 1965, and May–June 1965, whereas the 6 nights the lidar measured in December 1964 and January 1965 had sAOD values of at most ∼ 0.03. The comparison with interactive stratospheric aerosol model simulations of the Agung aerosol cloud shows that, although substantial variation in mid-latitude sAOD₅₃₂ are expected from the seasonal cycle in the stratospheric circulation, the Agung cloud's dispersion from the tropics would have been at its strongest in winter and weakest in summer. The increasing trend in sAOD from January to July 1965, also considering the large variability, suggests that the observed variations are from a different source than Agung, possibly from one or both of the two eruptions that occurred in 1964/1965 with a Volcanic Explosivity Index (VEI) of 3: Trident, Alaska, and Vestmannaeyjar, Heimaey, south of Iceland. A detailed error analysis of the uncertainties in each of the variables involved in the processing chain was conducted. Relative errors for the uncorrected sAEP₅₃₂ were 54 % for Fairbanks and 44 % Lexington. For the corrected sAEP₅₃₂ the errors were 61 % and 64 %, respectively. The analysis of the uncertainties identified variables that with additional data recovery and reprocessing could reduce these relative error levels. Data described in this work are available at https://doi.org/10.1594/PANGAEA.922105 (Antuña-Marrero et al., 2020a).

中文翻译：

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1964 年 1 月至 1965 年 7 月，从马萨诸塞州列克星敦和阿拉斯加州费尔班克斯恢复平流层气溶胶层的第一个多年激光雷达数据集

我们报告了平流层气溶胶层有史以来第一个多年激光雷达数据集的恢复和处理方法。1964 年 1 月至 1965 年 8 月期间，Q 开关红宝石激光雷达在马萨诸塞州列克星敦测量了 66 个 694 nm 衰减后向散射垂直剖面，并在 1964 年 7 月和 8 月期间在阿拉斯加大学进行了另外 9 次剖面测量。我们描述了处理恢复的激光雷达后向散射比剖面，以产生中可见光 (532 nm) 平流层气溶胶消光剖面 (sAEP ₅₃₂ ) 和平流层气溶胶光学深度 (sAOD ₅₃₂₎) 测量，利用对几个不同大气变量的许多当代测量。温度和压力的平流层探测产生准确的局部分子背向散射剖面，附近的臭氧探测决定臭氧吸收，用于校正双向臭氧透射率。根据太阳光度计测量的总气溶胶光学深度（跨越对流层和平流层）的附近观测，也应用了双向气溶胶透射率校正。我们表明，考虑到这些双向透射率效应，北半球中纬度地区 1964/1965 年平流层气溶胶层的光学厚度显着增加，然后~ 比耦合模型比对项目 6 (CMIP6) 火山强迫数据集大 50%。与未校正的数据集相比，组合透射率校正将 Lexington 的 sAOD ₅₃₂提高了 66%，费尔班克斯的 sAOD ₅₃₂提高了 27%，以及类似幅度的单个 sAEP ₅₃₂调整。与少数可用的当代测量结果的比较表明，与校正后的双向透射率值更吻合。在 1964 年 1 月至 1965 年 8 月的测量时间跨度内，校正后的列克星敦 sAOD ₅₃₂时间序列在三个不同的时期（1964 年 10 月、3 月）大幅高于 0.05 1965 年和 1965 年 5 月至 6 月，而激光雷达在 1964 年 12 月和 1965 年 1 月测量的 6 个晚上的 sAOD 值最多为～  0.03。与阿贡气溶胶云的交互式平流层气溶胶模型模拟的比较表明，虽然预计中纬度 sAOD _{532 的}显着变化与平流层环流的季节周期有关，但阿贡云在热带地区的分散在冬季和夏季最弱。1965 年 1 月至 7 月 sAOD 的增加趋势，也考虑到较大的可变性，表明观察到的变化来自与阿贡不同的来源，可能来自 1964/1965 年发生的火山爆发指数 (VEI) 为 3 的两次喷发之一或两者：Trident，阿拉斯加和 Vestmannaeyjar，Heimaey，南部冰岛。对加工链中涉及的每个变量的不确定性进行了详细的误差分析。未校正的 sAEP _{532 的}相对误差在费尔班克斯为 54%，在列克星敦为 44%。对于更正后的 sAEP ₅₃₂误差分别为 61% 和 64%。对不确定性的分析确定了通过额外的数据恢复和再处理可以降低这些相对误差水平的变量。这项工作中描述的数据可在 https://doi.org/10.1594/PANGAEA.922105（Antuña-Marrero 等人，2020a）上获得。