Abstract Despite much progress has been made in recent years, the estimation of terrestrial gross primary productivity (GPP) remains highly uncertain. Recent studies have demonstrated the usefulness of sun-induced chlorophyll fluorescence (SIF) from plants for estimating GPP. In this study, the relationships of GPP to SIF and Photochemical Reflectance Index (PRI) under different environmental conditions are established using carbon flux data at 61 sites distributed globally and coincident SIF data from OCO-2 and PRI data from MODIS. We analyzed OCO-2 SIF data at both 757 nm and 771 nm against instantaneous and daily GPP values derived from the tower flux data. Our results for these four cases are similar, and those with SIF at 757 nm and daily GPP show that: (1) a significant relationship is found between GPP and observed SIF (SIFobs) for all vegetation types (R2 = 0.53, RMSE = 4.28 μmol m−2 s−1 p

中文翻译：

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光化学反射指数 (PRI) 可用于改善总初级生产力 (GPP) 与阳光诱导的叶绿素荧光 (SIF) 之间的关系

摘要 尽管近年来取得了很大进展，但陆地总初级生产力（GPP）的估计仍然高度不确定。最近的研究证明了来自植物的阳光诱导的叶绿素荧光 (SIF) 可用于估计 GPP。在本研究中，利用分布在全球的 61 个站点的碳通量数据以及来自 OCO-2 的重合 SIF 数据和来自 MODIS 的 PRI 数据，建立了 GPP 与 SIF 和光化学反射指数（PRI）在不同环境条件下的关系。我们分析了 757 nm 和 771 nm 处的 OCO-2 SIF 数据与从塔通量数据得出的瞬时和每日 GPP 值。我们对这四种情况的结果相似，在 757 nm 处使用 SIF 和每日 GPP 的结果表明：