TROPOMI observations allow for robust exploration of the relationship between solar-induced chlorophyll fluorescence and terrestrial gross primary production
TROPOMI observations allow for robust exploration of the relationship between solar-induced chlorophyll fluorescence and terrestrial gross primary production
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DOI：
10.1016/j.rse.2021.112748
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发表时间：
2021-11-02
影响因子：
13.5
通讯作者：
Xiao, Jingfeng
中科院分区：
文献类型：
--
作者：
Li, Xing;Xiao, Jingfeng
卫星观测到的太阳诱导叶绿素荧光（SIF）推动了区域和全球对陆地光合作用的监测。近年来，在叶、冠层和生态系统尺度上，SIF与总初级生产力（GPP）的关系受到了极大的关注。在生态系统尺度上，SIF与GPP的关系是普遍的还是依赖于植被类型的，这一点仍然存在争议。对流层监测仪器（TROPOMI）的新SIF观测具有前所未有的高空间和时间分辨率，为阐明SIF与GPP的关系提供了新的机会。在这里，我们研究了SIF-GPP关系的七个主要植被类型在美国与TROPOMI SIF和原位GPP数据的83涡度协方差通量站点。我们发现，TROPOMI SIF显示了强大的和一致的关系，基于塔的GPP在卫星足迹和网格单元水平。除农田外，所有植被类型的SIF-GPP关系的斜率相似，表明SIF-GPP关系几乎是普遍的（收敛到类似于13.5 g C m（-2）d（-1）/W m（-2）mu m（-1）sr（-1）），而不是植被类型特定的SIF-GPP关系。这证实了TROPOMI SIF可以用作各种植被类型GPP的代理，也可以用来量化GPP，避免与土地覆盖图相关的不确定性。C-4作物的坡度比C-3作物高得多，因此耕地的坡度往往比C-3占主导地位的植被类型高（例如，森林、灌丛、稀树草原）。我们还发现，TROPOMI SIF是很好的相关性与GPP在正常或湿润条件下，而水分胁迫下，它们的关系变得较弱。我们基于TROPOMI的研究可以提高我们在生态系统尺度上对SIF-GPP关系的理解，并通过空间SIF观测推进全球GPP的映射。
Solar-induced chlorophyll fluorescence (SIF) observed by satellites has advanced the monitoring of terrestrial photosynthesis regionally and globally. The relationship between SIF and gross primary production (GPP) at leaf, canopy, and ecosystem scales has received tremendous attention in recent years. It remains controversial whether the SIF-GPP relationship at the ecosystem scale is universal or dependent upon vegetation type. New SIF observations from the TROPOspheric Monitoring Instrument (TROPOMI) with unprecedented high spatial and temporal resolution provide a new opportunity to elucidate the SIF-GPP relationship. Here, we examine the SIF-GPP relationship for seven major vegetation types across the U.S. with TROPOMI SIF and in-situ GPP data for 83 eddy covariance flux sites. We find that TROPOMI SIF shows a strong and consistent relationship with tower based GPP at both satellite footprint and grid-cell levels. The slope of the SIF-GPP relationship is similar among all the vegetation types except croplands, demonstrating a nearly universal (converging to similar to 13.5 g C m(-2) d(-1)/W m(-2) mu m(-1) sr(-1)) rather than vegetation type-specific SIF-GPP relationship. This confirms that TROPOMI SIF can be used as a proxy for GPP across a wide variety of vegetation types, and can also be used to quantify GPP by avoiding uncertainty associated with land cover maps. The C-4 crops have a much higher slope than the C-3 crops, and therefore croplands tend to have a higher slope than C-3-dominated vegetation types (e.g., forests, shrublands, savannas). We also find that the TROPOMI SIF is well correlated with GPP under normal or wetter conditions, while their relationship becomes weaker under water stress. Our TROPOMI-based study could improve our understanding of the SIF-GPP relationship at the ecosystem scale and advance the mapping of GPP globally with SIF observations from space.