Abstract. The National Institute for Environmental Studies has provided the column-averaged dry-air mole fraction of carbon dioxide and methane (XCO₂ and XCH₄) products (L2 products) obtained from the Greenhouse gases Observing SATellite for more than a decade. Recently, we updated the retrieval algorithm used to produce the new L2 product, V03.00. The main changes from the previous version (V02) of the retrieval algorithm are the treatment of cirrus clouds, the degradation model of the Thermal And Near-infrared Spectrometer for carbon Observation – Fourier Transform Spectrometer (TANSO-FTS), solar irradiance spectra, and gas absorption coefficient tables. The retrieval results from the updated algorithm showed improvements in fitting accuracies in the O₂ A, weak CO₂, and CH₄ bands of TANSO-FTS, although the residuals increase in the strong CO₂ band over the ocean. The direct comparison of the new product obtained from the updated (V03) algorithm with the previous version V02.90/91 and the validations using the Total Carbon Column Observing Network revealed that the V03 algorithm increases the amount of data without diminishing the data qualities of XCO₂ and XCH₄ over land. Further, the negative bias of XCO₂ is larger than that of the previous version over the ocean, and bias correction is still necessary. Additionally, the V03 algorithm resolves the underestimation of the XCO₂ growth rate compared with the in situ measurements over the ocean recently found using V02.90/91 and V02.95/96.

中文翻译：

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GOSAT TANSO-FTS SWIR Level 2 检索算法的更新

摘要。十多年来，美国国家环境研究所提供了从温室气体观测卫星中获得的二氧化碳和甲烷（XCO ₂和 XCH ₄）产物（L2 产物）的柱平均干空气摩尔分数。最近，我们更新了用于生产新 L2 产品 V​​03.00 的检索算法。与上一版本 (V02) 的检索算法的主要变化是卷云的处理、碳观测热和近红外光谱仪 - 傅里叶变换光谱仪 (TANSO-FTS) 的退化模型、太阳辐照度光谱和气体吸收系数表。更新算法的检索结果显示在 O _{2中的拟合精度有所提高}A，TANSO-FTS 的弱 CO ₂和 CH _{4波段，尽管海洋上的强 CO 2}波段的残差增加。通过更新（V03）算法获得的新产品与之前版本 V02.90/91 的直接比较以及使用 Total Carbon Column Observing Network 的验证表明，V03 算法在不降低数据质量的情况下增加了数据量XCO ₂和 XCH ₄在陆地上。此外，XCO ₂的负偏差比之前的版本在海洋上的偏差要大，仍然需要进行偏差校正。此外，V03 算法解决了对 XCO _2的低估与最近使用 V02.90/91 和 V02.95/96 发现的海洋原位测量结果相比，增长率。