Global Water Body Levels Derived from ICESat-2

This dataset contains water level records derived from ICESat-2 for 227,386 lakes spanning Oct 14, 2018 to July 16, 2020. These records have been updated to reflect an error in the calculation of lake area in the previous version which led to an overestimation of lake area at high latitudes. For details on how this correction was performed, please see the 2023 Addenda to Cooley et al (2021). A complete description of the method used to derive water level from ICESat-2 can be found in Cooley et al (2021), but is briefly summarized below: We create a conservative water mask modified from the Global Surface Water Occurrence (GSWO) product (Pekel et al., 2016); We intersect ATL08 mean terrain height returns with this water mask, requiring water bodies to receive at least three ICESat-2 point observations on the same day to be included in the analysis; We filter observations based on the mean standard deviation of returns, among other factors; We aggregate observations to monthly timesteps; We calculate seasonal variability in water level as the maximum minus the minimum monthly water level over the 22-month period. This dataset contains: <strong>ICESat2_lake_variability_v2_updated.shp</strong>: A shapefile containing lake points and summary statistics (i.e. height variability, storage variability, etc) <em>*updated to include corrected lake area and storage values</em> <strong>ICESat2_lake_height_time_series_v2_updated.csv</strong>: A csv file of the monthly water height time series used to calculate the global lake level variability <em>*updated to include corrected lake area values</em> <strong>265 water mask GeoTiffs</strong>: Water masks created from GSWO which we intersect with ICESat-2 data to produce the water level time series <em>*unchanged from previous version</em> <strong>ICESat2_mask_reference_v2_updated.csv</strong> – A csv file which lists the corresponding water mask for each water body in the dataset <em>*updated to include corrected lake area values</em> <strong>USGS_height_validation_v2_updated.csv </strong>– A csv file containing the height comparison between ICESat-2 and USGS gauges used for validation and uncertainty analyses <em>*updated to include corrected lake area values</em> <strong>USGS_range_validation_ v2_updated</strong>.<strong>csv </strong>– A csv file containing the range comparison between ICESat-2 and USGS gauges used for validation and uncertainty analyses <em>*updated to include corrected lake area values</em> <strong>California_storage_validation_v2_updated.csv </strong>– A csv file containing the storage comparison between ICESat-2 and California Department of Water Resource gauges used for validation and uncertainty analyses <em>*updated to include corrected lake area and storage values</em> See the README file for a more detailed description of this dataset. Anyone wishing to use this dataset should cite Cooley et al. 2021) and contact Sarah Cooley at [e-mail] with a description of the work and any questions so that we may offer guidance in regards to the best usage of our dataset. Cooley, S.W., Ryan, J.C., and Smith, L.C., (2021), Human alteration of global surface water storage variability, <em>Nature, </em>https://doi.org/10.1038/s41586-021-03262-3本数据集涵盖2018年10月14日至2020年7月16日期间，针对227386个湖泊的ICESat-2水位观测数据。本次更新修正了旧版本中湖泊面积计算的误差——该误差曾导致高纬度地区湖泊面积被高估。有关本次修正的具体实施细节，请参阅Cooley等人（2021）研究的2023年补编。 有关从ICESat-2数据反演水位的完整方法说明，请参见Cooley等人（2021）的研究，下文将对其进行简要概述： 1. 基于全球地表水体发生（Global Surface Water Occurrence, GSWO）数据集（Pekel等，2016），构建保守型水体掩膜； 2. 将ATL08平均地形高度反演值与该水体掩膜进行叠加分析，要求同一日期内至少有3个ICESat-2点位观测到水体，方可纳入后续分析； 3. 基于反演值的平均标准差等多项指标对观测数据进行筛选； 4. 将观测数据聚合为月时间步长序列； 5. 以22个月周期内的月度水位最大值与最小值之差，计算水位季节变化幅度。 本数据集包含以下文件： <strong>ICESat2_lake_variability_v2_updated.shp</strong>：该矢量shapefile包含湖泊点位及各类汇总统计量（如水位变化幅度、储水量变化幅度等），*已更新为修正后的湖泊面积与储水量数值* <strong>ICESat2_lake_height_time_series_v2_updated.csv</strong>：用于计算全球湖泊水位变化幅度的月度水位时间序列CSV文件，*已更新为修正后的湖泊面积数值* <strong>265份水体掩膜GeoTiff文件</strong>：基于GSWO数据集生成的水体掩膜，用于与ICESat-2数据叠加以生成水位时间序列，*与旧版本无差异* <strong>ICESat2_mask_reference_v2_updated.csv</strong>：列明本数据集内每个水体对应水体掩膜的CSV文件，*已更新为修正后的湖泊面积数值* <strong>USGS_height_validation_v2_updated.csv</strong>：用于验证与不确定性分析的ICESat-2与美国地质调查局（United States Geological Survey, USGS）水位计观测值对比CSV文件，*已更新为修正后的湖泊面积数值* <strong>USGS_range_validation_v2_updated.csv</strong>：用于验证与不确定性分析的ICESat-2与USGS水位计观测值变幅对比CSV文件，*已更新为修正后的湖泊面积数值* <strong>California_storage_validation_v2_updated.csv</strong>：用于验证与不确定性分析的ICESat-2与加州水资源部（California Department of Water Resource）水位计储水量对比CSV文件，*已更新为修正后的湖泊面积与储水量数值* 有关本数据集的更详细说明，请参阅附带的README文件。 任何使用本数据集的研究人员，请引用Cooley等人（2021）的研究成果，并通过[e-mail]邮箱联系Sarah Cooley，告知您的研究内容与相关疑问，以便我们为您提供数据集最佳使用方式的指导建议。 Cooley, S.W.、Ryan, J.C.与Smith, L.C.（2021），《人类活动对全球地表水体储水变化的影响》，*Nature*，https://doi.org/10.1038/s41586-021-03262-3