Analysis of peatland carbon dynamics using combined optical and microwave satellite data

该项目旨在制定遥感方案，通过植物对干旱和复湿的光合反应，研究恢复的泥炭地对干旱条件的适应能力，特别是不同泥炭地微形态的适应能力。它们从大气中吸收了大量的碳。形成泥炭的植物，特别是泥炭藓类植物，如泥炭藓，很好地适应了这种潮湿的环境，但在干燥的条件下会受到损害。不列颠群岛的许多泥炭地都受到了有害的管理计划，包括排水，过度放牧，商业林业种植和燃烧。虽然现在已经开展了大规模的恢复工作，但要完全恢复这些地点的水文特征往往具有挑战性。这使它们容易受到干旱时期的影响，在干旱期间，可以观察到泥炭地植被的光合作用以及最终的碳排放受到明显的负面影响。随着哨兵-1和哨兵-2任务的出现，过去几年中可用于研究泥炭地的地球观测卫星数量有所增加。哨兵-1号卫星携带的合成孔径雷达仪器对土壤和植物湿度敏感，关键是不受云层的影响，否则云层往往会限制泥炭地地区的光学/红外测量。Sentinel-2卫星携带对电磁光谱的可见光和近红外部分敏感的光学仪器。这使它们成为监测植物健康的理想选择。将来，我们还将从欧洲航天局的FLEX地球探测器使命中直接观测光合作用（计划于2022年发射），测量植物的太阳诱导荧光（SIF）。学生将研究当前和未来卫星微波雷达，可见光，红外，和SIF平台，用于遥感泥炭地的干旱响应，并测试在景观尺度上遥感监测泥炭地恢复力的可行性。研究工作福尔斯三个部分：1）基于实验的不同泥炭地微形态的干燥和再润湿响应的研究。我们将在蒸渗仪上进行这些实验，并使用UoR的地面雷达系统进行定期测量，该系统配置为与Sentinel-1测量相匹配。模拟哨兵-2的光学测量将与合成孔径雷达观测同时进行。这些将一起用于校准干燥和再润湿响应的联合SAR光学模型2）光学和SIF测量的基于现场的研究。学生将在1-2年期间进行实地活动，用手持光学仪器监测恢复和未恢复的网站。这些数据，以及现场土壤湿度和总初级生产力数据（JHI长期涡动协方差监测数据集）将使我们能够测试模型（1）。SIF数据将用于探索FLEX等任务的额外好处。3)研究2018年的干旱，这为了解泥炭地水分胁迫的遥感信号提供了一个难得的机会。将提取2018年福尔西纳尔流量的Sentinel-1和2数据，并根据（1）和（2）中建立的关系探索当年干旱对泥炭地的影响。

This project aims to develop remote sensing schemes for examining the resilience of restored peatlands to drought conditions, particularly of different peatland microforms, through the plant photosynthetic response to drought and rewetting.Peatlands are a key component of the terrestrial carbon cycle. They sequester large amounts of carbon from the atmosphere. Peat-forming plants, and especially bryophytes such as Sphagnum mosses, are well adapted to this wet environment but suffer disproportionally in dry conditions. Many peatlands in the British Isles have been subject to deleterious management schemes, including drainage, overgrazing, planting for commercial forestry, and burning. Although large-scale restoration efforts have now been implemented, it is often challenging to completely restore the hydrological characteristics of such sites. This leaves them vulnerable to drought periods, during which markedly negative effects on photosynthesis of peatland vegetation, and ultimately carbon emissions, can be observed. The number of Earth Observation satellites available to study peatlands has risen in the past few years with the advent of the Sentinel-1 and Sentinel-2 missions. The Sentinel-1 satellites carry synthetic aperture radar (SAR) instruments which are sensitive to soil and plant moisture and, critically, are not affected by cloud cover which can often otherwise restrict optical/IR measurements of peatland areas. The Sentinel-2 satellites carry optical instruments that are sensitive to the visible and near infra-red parts of the electromagnetic spectrum. This makes them ideal for monitoring plant health. In future, we will also have direct observations of photosynthesis from the European Space Agency's FLEX Earth Explorer mission (planned launch 2022), which measures Solar Induced Fluorescence (SIF) from plants.The student will investigate the synergistic exploitation of current and future satellite microwave radar, visible, infrared, and SIF platforms for the remote sensing of drought responses of peatlands and test the feasibility of remotely monitoring peatland resilience on a landscape scale. The work falls into three components:1) Laboratory-based study of the drying and rewetting response of different peatland microforms. We will house these experiments on a lysimeter and take regular measurements with UoR's ground-based radar system configured to match Sentinel-1 measurements. Optical measurements to simulate Sentinel-2 will be taken alongside the SAR observations. Together these will be used to calibrate a joint SAR-optical model of drying and rewetting responses 2) Field-based studies of optical and SIF measurements. The student will conduct a field campaign during year 1-2 to monitor restored and non-restored sites with hand-held optical instruments. These data, alongside in-situ soil moisture and gross primary production data (JHI long term eddy covariance monitoring datasets) will allow us to test models devolved in (1). The SIF data will be used to explore the additional benefit of missions such as FLEX. 3) Examine the 2018 drought, which provides an exceptional opportunity to understand the remote sensing signals of peatland water stress. The Sentinel-1 and 2 data for 2018 will be extracted for the Forsinard flows and the impact of the drought of that year on the peatlands will be explored based on the relationships built in (1) and (2).