南极中山站长期(1993-2023年)再分析臭氧总量地基观测验证及趋势

    Validation of the Long-term (1993-2023) Reanalysis of Total Ozone Column and Their Trends at Zhongshan Station in Antarctica

    • 基于南极中山站1993-2023年Brewer光谱仪地基观测大气臭氧总量(Ω), 对再分析数据MERRA2和ERA5的臭氧总量进行验证、评估和趋势分析. 研究发现, 再分析数据与地基测值在反映南极臭氧洞及臭氧总量季节变化方面是一致的. 日均 MERRA2和ERA5的臭氧总量差异浓度值(ΔΩ)分别为–2.0±9.6 DU和3.2±7.8 DU, 相对差异分布均呈随机特征. 1993-2004年和2005-2023年两个时段的臭氧洞(地基Ω ≤220 DU)期间, MERRA2的相对差异百分比 ΔR 均值分别为6.9%±4.6%和–0.4%±2.3%, 而ERA5则分别为4.6%±2.0%和6.4%±3.1%; 随着太阳天顶角θ 的上升, MERRA2 与ERA5的 ΔR 在1993-2004年分别呈现总体幅度为3%和2%的上升, 而在2005-2023年则分别呈–2%下降和2%上升; 2005-2023年的再分析臭氧总量数据质量优于1993-2004年. 经Brewer光谱仪测值订正后的再分析数据均表现出Ω 的恢复态势, 其中ERA5的恢复速率每10年为 1.3 DU. 再分析数据在被地基验证和订正之前应慎用于评估南极大气臭氧总量长期趋势变化. 地基臭氧总量观测时数虽然受太阳天顶角或天气影响而远低于再分析数据, 但对再分析数据的验证是评估臭氧总量长期变化的关键依据.

       

      Abstract: Based on the Brewer ozone spectrophotometer long-term (1993-2023) observations at Zhongshan Station, Antarctica, the atmospheric Total Ozone Column (TOC) of the MERRA2 and ERA5 reanalysis are compared, evaluated, and their trends are analyzed. The results show that the reanalysis is generally in good agreement with the ground-based data in the context of occurrence of the ozone hole and the TOC seasonality. The TOC bias (ΔΩ) on the daily mean scale is –2.0±9.6 DU and 3.2±7.8 DU for MERRA2 and ERA, respectively. Both the probability distributions of the reanalysis ΔΩ exhibit normal random processes and their large variations occurred at the end of March and during the ozone hole period. The reanalysis data were divided into two periods, 1993-2004 and 2005-2023, based on the changes of satellites to which the reanalysis data were assimilated, but the ΔΩ values (including ERA5) during the ozone hole increases with decreasing of the TOC in the both periods, and the ΔR values for MERRA2/ERA5 were 6.9%±4.6%/4.6%±2.0% and –0.4%~2.3%/6.4%±3.1%, respectively. The ΔR of MERRA2 and ERA5 show an increasing trend with the Solar Zenith Angle (SZA) during 1993-2004, with each magnitude of 3% and 2%, while the opposite trend is observed from 2005 to 2023, with magnitudes of –2% and 2% for MERRA2 and ERA5, respectively. The quality of reanalysis TOC data from 2005 to 2023 is superior to that from 1993 to 2004. Both the reanalysis TOC data validated by Brewer show their consistent recovery trends of TOC, and the linearly fitted recovery rate of ERA5 is 1.3 DU per decade. The study suggests that raw reanalysis TOC data should be used with much caution before evaluating the long-term trends of the ozone layer, and the data from the ground-based observations, although the number of the data is much less than that of reanalysis outputs due to seasonal SZA or weather conditions, is critical for the reanalysis TOC validation and conclusions of the TOC trend.

       

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