Data accompanying "Summer drought weakens land surface cooling of tundra vegetation"

This dataset contains the spatial and meteorological data underlying the statistical analysis in: Rietze et al. (in press) - Summer drought weakens land surface cooling by tundra vegetation All code to preprocess, analyze and visualize this data can be found under https://github.com/nrietze/ArcticDroughtPaper. This dataset contains three major components: The drone-derived mosaics of multispectral, RGB, and thermal imagery. The training polygons used for the land cover classification. Meteorological and micrometeorological observations used in the analysis and descriptions of flight conditions. Internal data from the drone flights. Folder structure: └───data
├───landcover
├───mosaics
├───shapefiles
└───tables
├───intermediate
└───results Clone the Github repository before downloading this data and insert the contents of this dataset into the empty "data" folder from the Github repo. Cite as: Rietze, Nils, Assmann, Jakob J., Damm, Alexander, Naegeli, Kathrin, Karsanaev, Sergey V., Maximov, Trofim C.,Plekhanova, Elena, Schaepman-Strub, Gabriela. (in press). Summer drought weakens land surface cooling of tundra vegetation. Abstract (from manuscript): Siberia experienced a prolonged heat wave in the spring of 2020, resulting in extreme summer drought and major wildfires in the North Eastern Siberian lowland tundra. In the Arctic tundra, plants play a key role in regulating the summer land surface energy budget by contributing to land surface cooling through evapotranspiration. Yet we know little about how drought conditions impact plant-mediated land surface cooling by tundra plant communities, and related positive feedback to the high air temperatures. Here we used high-resolution land surface temperature and vegetation maps based on drone imagery to determine the impact of the extreme summer drought in 2020 on land surface cooling in the lowland tundra of North-Eastern Siberia. We found strong differences in land surface cooling among plant communities in the drought year 2020 and the reference year 2021. Further, we observed a decrease in the normalized land surface cooling between the two years using the water deficit index (WDI) across all plant communities during the drought year. This shift indicates an energy budget regime dominated by sensible heat fluxes, contributing to land surface warming. Overall, our findings suggest significant variation in land surface cooling among common Arctic plant communities in the North-Eastern Siberian lowland tundra and a pronounced effect of drought on all community types. Based on our results we suggest accounting for tundra plant communities if we want to accurately predict the impacts and consequences of droughts on land surface cooling and energy flux related processes such as permafrost thaw and wildfires. Acknowledgements (from manuscript): N.R. was supported through the TRISHNA Science and Electronics Contribution (T-SEC), an ESA PRODEX project (contract no. 4000133711). Drone data acquisition was supported by the University Research Priority Program on Global Change and Biodiversity of the University of Zurich and by the Swiss National Science Foundation (grant no. 178753). We would like to thank Geert Hensgens of VU Amsterdam for sharing the flux tower data at the research site with us.

本数据集包含Rietze等人（已录用）《夏季干旱削弱苔原植被地表降温作用》一文统计分析所依托的空间与气象数据。所有用于数据预处理、分析与可视化的代码可于https://github.com/nrietze/ArcticDroughtPaper 获取。

本数据集包含三大核心组成部分：1. 无人机（drone）生成的多光谱、RGB（红-绿-蓝）与热红外影像镶嵌图；2. 用于土地覆盖分类的训练多边形样本；3. 分析所用的气象与微气象观测数据、飞行条件描述，以及无人机飞行的内部数据。

文件夹结构如下：
└── data
├── landcover
├── mosaics
├── shapefiles（形状文件（Shapefile）
└── tables
├── intermediate
└── results

请先克隆该GitHub仓库，下载本数据集，并将数据集内容放入该GitHub仓库中预留的空data文件夹内。

引用方式如下：
Rietze, Nils, Assmann, Jakob J., Damm, Alexander, Naegeli, Kathrin, Karsanaev, Sergey V., Maximov, Trofim C., Plekhanova, Elena, Schaepman-Strub, Gabriela.（已录用）. 夏季干旱削弱苔原植被地表降温作用.

论文摘要：
2020年春季，西伯利亚遭遇持续热浪，导致东北西伯利亚低地苔原地区出现极端夏季干旱与大规模野火。北极苔原中的植被通过蒸散作用实现地表降温，在调节夏季地表能量收支中发挥关键作用。然而目前我们对干旱条件如何影响苔原植物群落介导的地表降温，及其对高温的相关正反馈机制仍知之甚少。
本研究基于无人机（drone）影像获取高分辨率地表温度与植被分布图，以此探究2020年极端夏季干旱对东北西伯利亚低地苔原的地表降温效应。研究发现，干旱年2020年与参照年2021年，不同植物群落的地表降温能力存在显著差异。此外，在干旱年，基于水分亏缺指数（Water Deficit Index, WDI，所有植物群落的标准化地表降温值在两年间均有所下降。这一变化表明，当年的能量收支以感热通量为主导，进而推动地表升温。
总体而言，本研究结果表明，东北西伯利亚低地苔原的常见北极植物群落间，地表降温能力存在显著差异，且干旱对所有群落类型均有显著影响。基于本研究结果，若要准确预测干旱对地表降温以及与能量通量相关的过程（如多年冻土融化与野火）的影响与后果，建议将苔原植物群落纳入考量范畴。

致谢（来自论文手稿）：
N.R. 得到TRISHNA科学与电子贡献项目（TRISHNA Science and Electronics Contribution, T-SEC）资助，该项目属于欧洲空间局（European Space Agency, ESA）PRODEX计划（合同编号：4000133711。
无人机数据采集工作得到苏黎世大学全球变化与生物多样性大学研究优先项目，以及瑞士国家科学基金会（Swiss National Science Foundation，项目编号：178753）资助。
本研究感谢阿姆斯特丹自由大学（VU Amsterdam）的Geert Hensgens，向我们分享了研究站点的通量塔观测数据。