Pan-Arctic surface water (yearly and trend over time) 2000-2022

Surface water change has been documented across the Arctic due to thawing permafrost and changes in the precipitation/evapotranspiration balance. This dataset uses Moderate Resolution Imaging Spectroradiometer (MODIS) data to track changes in surface water across the region over the past two decades. The superfine water index (SWI) is a unitless global water cover index developed specifically for MODIS data and validated in high northern latitudes. Variation in SWI can also track changes in surface water that occur at the sub-MODIS pixel scale (i.e., changes in water bodies smaller a MODIS pixel, ~500 meters (m)). This dataset (1) maps the average July SWI over pan-Arctic for each year of the MODIS record (2000-2021) and (2) maps the trends in July SWI over 2000-2012 (i.e., Sen's slope of the pixel-wise SWI vs. time). The spatial resolution of this dataset is ~500 m. The yearly SWI files are processed for the entire continuous and discontinuous permafrost zone. The 2000-2021 trend file is processed for lake-rich regions of the Arctic (i.e., lake coverage greater than 5%), as was published in the Webb et al, 2022 paper. The 2000-2022 trend file is processed for the entire continuous and discontinuous permafrost zone. Corresponding publication: Webb, Elizabeth E., Anna K. Liljedahl, Jada A. Cordeiro, Michael M. Loranty, Chandi Witharana, and Jeremy W. Lichstein (2022), Permafrost thaw drives surface water decline across lake-rich regions of the Arctic, Nature Climate Change, doi.org/10.1038/s41558-022-01455-w

由于永久冻土融化与降水-蒸散平衡改变，北极地区的地表水变化已被广泛记录。本数据集采用中等分辨率成像光谱仪（Moderate Resolution Imaging Spectroradiometer, MODIS）数据，追踪过去二十年间该区域的地表水变化。
超精细水体指数（Superfine Water Index, SWI）是一种专为MODIS数据开发的无量纲全球水体覆盖指数，已在高北纬地区完成验证。SWI的变化还可捕捉到亚MODIS像元尺度下的地表水变化（即小于MODIS约500米像元的水体变化）。
本数据集包含两类成果：（1）绘制了2000-2021年MODIS观测记录中，泛北极区域每年7月的平均SWI空间分布；（2）绘制了2000-2012年7月SWI的变化趋势（即逐像元SWI随时间变化的森斜率）。该数据集的空间分辨率约为500米。
逐年度SWI文件覆盖了连续与非连续永久冻土全域。其中2000-2021年趋势文件覆盖北极富湖区域（即湖泊覆盖率大于5%的区域），对应Webb等人2022年发表的研究成果。而2000-2022年趋势文件则覆盖连续与非连续永久冻土全域。
相关发表文献：Webb, Elizabeth E., Anna K. Liljedahl, Jada A. Cordeiro, Michael M. Loranty, Chandi Witharana, 及 Jeremy W. Lichstein (2022)，《永久冻土融化导致北极富湖区域地表水减少》，《自然·气候变化》，doi.org/10.1038/s41558-022-01455-w