东亚地区植被光合日内变化特征--融合OCO-3和Himawari-8的分析

Analysis of diurnal variation of vegetation photosynthesis in East Asia by fusing OCO⁃3 and Himawari⁃8

日光诱导叶绿素荧光(SIF)是植物在太阳光照射条件下发出的光谱信号,直接反映了植被光合作用的强度,对于陆地植被观测至关重要。然而,目前全球SIF传感器的时空分辨率有限,难以捕捉光合作用的日内变化。利用搭载在国际空间站的轨道碳观测者三号卫星和静止卫星向日葵8号的数据,结合随机森林回归算法,重建了东亚地区2019—2022年生长季内7、8、9月时间分辨率为1h、空间分辨率为0.05°的SIF数据集。结果显示,东亚地区植被SIF值在上午逐渐增加,中午达到峰值,下午逐渐减小。不同月份的SIF日内变化呈现出明显的季节性特征,与夏季阳光充足和气温较高相关。不同植被类型间的SIF日内变化差异反映了它们在光合作用响应性上的特征。这些结果有助于深入理解东亚地区植被的时空动态,为生态系统管理、农业生产及气候变化响应策略提供了重要的科学依据和参考。

Solar-induced chlorophyll fluorescence(SIF)is a spectral signal emitted by plants under sunlight irradiation,directly reflecting the intensity of photosynthesis and is of great importance for land vegetation observation.However,the spatial and temporal resolutions of global SIF sensors is limited,making it difficult to capture intra-day changes in photosynthesis.In this study,we reconstructed a 1-hourly and 0.05°spatially resolved SIF dataset for July,August,and September of 2019—2022 in East Asia using data from the Orbiting Carbon Observatory-3(OCO-3)and Himawari-8 satellites,which were launched on the International Space Station and are geostationary satellites,respectively.The results show that the SIF values of vegetation in East Asia gradually increase in the morning,reach a peak at noon,and gradually decrease in the afternoon.The intra-day SIF variations in different months show obvious seasonal characteristics,which are related to abundant sunlight and high temperatures in summer.The differences in intra-day SIF variations between different vegetation types reflect their characteristics in photosynthetic response.These results contribute to a deeper understanding of the spatial and temporal dynamics of vegetation in East Asia,providing important scientific basis and references for ecosystem management,agricultural production,and climate change response strategies.