The accuracy of atmospheric trace gas retrievals depends directly on the accuracy of the molecular absorption model used within the retrieval algorithm. For remote sensing of well-mixed gases, such as carbon dioxide (CO₂), where the atmospheric variability is small compared to the background, the quality of the molecular absorption model is key. Recent updates to oxygen (O₂) absorption coefficients (ABSCO) for the 0.76 µm A-band and the water vapor (H₂O) continuum model within the 1.6 µm and 2.06 µm CO₂ bands used within the Orbiting Carbon Observatory (OCO-2 and OCO-3) algorithm are described here. Updates in the O₂ A-band involve the inclusion of new laboratory measurements within multispectrum fits to improve relative consistency between O₂ line shapes and collision-induced absorption (CIA). The H₂O continuum model has been updated to MT$\_$CKD v3.2, which has benefited from information from a range of laboratory studies relative to the model utilized in the previous ABSCO version. Impacts of these spectroscopy updates have been evaluated against ground-based atmospheric spectra from the Total Carbon Column Observing Network (TCCON) and within the framework of the OCO-2 algorithm, using OCO-2 soundings covering a range of atmospheric and surface conditions. The updated absorption coefficients (ABSCO version 5.1) are found to offer improved fitting residuals and reduced biases in retrieved surface pressure relative to the previous version (ABSCO v5.0) used within B8 and B9 of the OCO-2 retrieval algorithm and have been adopted for the OCO B10 Level 2 algorithm.

大气痕量气体检索的准确性直接取决于检索算法中使用的分子吸收模型的准确性。对于遥感的混合气体（例如二氧化碳（CO ₂）），与背景相比，大气变化较小，因此分子吸收模型的质量至关重要。轨道碳观测站（OCO- ）使用的0.76 µm A波段氧气和O ₂吸收谱系（ABSCO）和1.6 µm和2.06 µm CO ₂波段内的水蒸气（H ₂ O）连续谱模型的最新更新。这里描述2和OCO-3）算法。O _2中的更新A波段涉及在多光谱拟合中包含新的实验室测量值，以改善O ₂线形与碰撞诱导吸收（CIA）之间的相对一致性。H ₂ O连续体模型已更新为MT$\_$CKD v3.2，它受益于与先前ABSCO版本中使用的模型有关的大量实验室研究信息。这些光谱更新的影响已针对来自总碳柱观测网络（TCCON）的地面大气光谱进行了评估，并在OCO-2算法的框架内，使用涵盖了一系列大气和地面条件的OCO-2测深法进行了评估。发现更新的吸收系数（ABSCO版本5.1）相对于OCO-2检索算法的B8和B9中使用的先前版本（ABSCO v5.0）可提供改进的拟合残差和减小的检索表面压力偏差，并且已被采用适用于OCO B10 2级算法。