This study presents the validation of total column ozone (TCO) data retrieved from the Geostationary Environment Monitoring Spectrometer (GEMS) against ground-based Pandora spectrometer observations during the GEMS Map of Air Pollution (GMAP) campaign from November 2020 to January 2021 in Seosan, South Korea. To evaluate the accuracy of the Pandora TCO measurements obtained during the campaign period, all Pandora instruments were installed at the Seosan supersite for intercomparison analysis. Subsequently, the instruments were relocated to four sites for direct sunlight measurements. The Pandora instruments exhibited a high degree of consistency with an average difference of 0.5 ± 1.0 DU. This study demonstrated that accurate comparison of ground-based ozone measurements with satellite ozone measurements depended on the threshold values set for the spatial and temporal alignment of the two datasets and the size of the satellite footprint and viewing angle. The comparison of the GEMS, TROPOspheric Monitoring Instrument (TROPOMI), and Ozone Mapping and Profiler Suite Nadir Mapper (OMPS) satellite TCO with the Pandora TCO showed high agreement across measurements. However, a distinct downward trend was observed in the Mean Bias (MB) for GEMS from December–January, indicating an issue with the GEMS Level 1C irradiance. The validation using hourly Pandora data demonstrated GEMS capability to monitor daily ozone variations but with a bias of approximately −1% to −2.6% compared with that of Pandora.

中文翻译：

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在 GEMS 空气污染地图 (GMAP) 现场活动期间使用潘多拉测量验证对地静止环境监测光谱仪 (GEMS)、对流层监测仪器 (TROPOMI) 以及臭氧绘图和剖面仪套件最低点绘图仪 (OMPS)

本研究介绍了从地球静止环境监测光谱仪 (GEMS) 检索到的总柱臭氧 (TCO) 数据与 2020 年 11 月至 2021 年 1 月瑞山市空气污染地图 (GMAP) 活动期间地面潘多拉光谱仪观测结果的验证，韩国。为了评估活动期间获得的 Pandora TCO 测量结果的准确性，所有 Pandora 仪器都安装在 Seosan 超级站点进行比对分析。随后，仪器被转移到四个地点进行直射阳光测量。Pandora 仪器表现出高度的一致性，平均差异为 0.5 ± 1.0 DU。这项研究表明，地面臭氧测量值与卫星臭氧测量值的准确比较取决于为两个数据集的空间和时间对齐设置的阈值以及卫星足迹的大小和视角。GEMS、TROPOspheric 监测仪器 (TROPOMI) 以及臭氧测绘和剖面仪套件最低点测绘器 (OMPS) 卫星 TCO 与 Pandora TCO 的比较表明测量结果高度一致。然而，从 12 月到 1 月，GEMS 的平均偏差 (MB) 出现明显下降趋势，表明 GEMS 1C 级辐照度存在问题。使用每小时 Pandora 数据进行的验证表明，GEMS 能够监测每日臭氧变化，但与 Pandora 相比存在约 -1% 至 -2.6% 的偏差。