SAMBA – Solar-induced chlorophyll fluorescence (SIF) in the AMazon BAsin

通过光合作用的总初级生产力（GPP）是大气CO2的单一最大吸收机制，因此驱动了人为CO2排放的气载部分的变化。大量的碳在热带雨林中循环，全球约占光合作用（GPP）吸收二氧化碳的34%。然而，由于传统测量方法的大偏差，热带雨林的全球生产力仍然知之甚少。为了解决这一关键的知识差距，“桑巴舞-亚马逊盆地太阳能诱导叶绿素荧光（SIF）”项目旨在量化热带雨林的碳吸收和光合作用，并分析它们如何与环境条件联系在一起。我们建议利用一种新的观测方法来检测太阳诱导叶绿素荧光（SIF），这是一个指标的光合活性，并提供了估计GPP。在光合作用期间，叶绿素吸收的部分太阳辐射在吸收光合有效辐射（PAR）之后以较长波长（650 - 850 nm）重新发射，所谓的SIF在红色（~685 nm）和远红色（~740 nm）光谱区域具有两个发射峰。然而，冠层观测，这是需要连接在现场的叶片数据与遥感的全球尺度的SIF数据，稀疏。拟议的工作将建立在申请人使用最近开发的下一代冠层应力强度因子仪器- PhotoSpec -进行空间分辨的同时进行的红光和远红光应力强度因子和植被指数观测的经验基础上。PhotoSpec仪器将基于2015年至2018年在加州大学洛杉矶分校开发的原始PhotoSpec设计，包括针对热带雨林部署进行的修改。该仪器将部署在巴西的亚马逊雨林进行数据收集，以获得对SIF和生态系统GPP的连续估计。我们建议利用这一全面的数据集与现有的一套碳循环观测和土壤冠层模型，调查季节性物候，CO2通量的变化，并最终大气CO2从热带雨林的命运。这些活动的数据将改进关于SIF和总CO2通量的基于过程的知识，这是更好地约束光合作用过程和碳通量的模型模拟所迫切需要的。这些活动将推动大气、生物和环境科学交叉领域的基础研究，并为评估气候变化的预测反馈提供关键信息。

Gross Primary Production (GPP) through photosynthesis is the single largest uptake mechanism of atmospheric CO2 and thus drives the variability of the airborne fraction of anthropogenic CO2 emissions. A significant amount of carbon is cycled through tropical rainforests, globally accounting for about 34% of CO2 uptake by photosynthesis, or GPP. However, GPP in tropical rainforests remains poorly understood due to large biases of traditional measurement methods. To address this critical knowledge gap, the project ‚SAMBA – Solarinduced chlorophyll fluorescence (SIF) in the Amazon Basin‘ aims to quantify the carbon uptake and photosynthesis of tropical rainforests and to analyze how they are linked to environmental conditions. We propose to make use of a new observation method to detect solarinduced chlorophyll fluorescence (SIF), which is an indicator for photosynthetic activity and provides an estimation of GPP. During photosynthesis, parts of the solar radiation absorbed by chlorophyll are re-emitted at longer wavelengths (650 – 850 nm) after absorption of photosynthetically active radiation (PAR), so-called SIF with two emission peaks in the red (~685 nm) and the far-red (~740 nm) spectral region. However, canopy observations, which are needed to link in-situ leaf data with remotely-sensed global scale data of SIF, are sparse. The proposed work will build on the applicant‘s experiences using the recently developed next- generation canopy SIF instrument - PhotoSpec - to perform spatially resolved simultaneous red and far-red SIF and vegetation index observations. A PhotoSpec instrument will be build based on the original PhotoSpec design developed at UCLA between 2015 and 2018, including modifications adjusted for tropical rainforests deployments. The instrument will be deployed in the Amazon rainforest of Brasil for data collection to obtain continuous estimates of SIF and ecosystem GPP. We propose to exploit this comprehensive data set with an existing set of carbon cycle observations and soil-canopy models to investigate changes in seasonal phenology, CO2 fluxes, and ultimately the fate of atmospheric CO2 from tropical rainforests. Data from the activities will improve the process-based knowledge on SIF and gross CO2 fluxes that is urgently needed to better constrain model simulations of photosynthetic processes and carbon fluxes. These activities will advance fundamental research at the intersection of atmospheric, biological and environmental sciences, and provide critical information to evaluate the predicted feedbacks of climate change.