GMEX_hIPR: The half-interpercentile range of bottom shear stress for the Gulf of Mexico, May 2010 to May 2011 (Geographic, WGS 84)

The U.S. Geological Survey has been characterizing the regional variation in shear stress on the sea floor and sediment mobility through statistical descriptors. The purpose of this project is to identify patterns in stress in order to inform habitat delineation or decisions for anthropogenic use of the continental shelf. The statistical characterization spans the continental shelf from the coast to approximately 120 m water depth, at approximately 0.04-0.06 degree (5-7 km, depending on latitude) resolution. Time-series of wave and circulation are created using numerical models, and near-bottom output of steady and oscillatory velocities and an estimate of bottom roughness are used to calculate a time-series of bottom shear stress at 1-hour intervals. Statistical descriptions such as the median and 95th percentile, which are the output included with this database, are then calculated to create a two-dimensional picture of the regional patterns in shear stress. In addition, time-series of stress are compared to critical stress values at select points calculated from observed surface sediment texture data to determine estimates of sea floor mobility.

美国地质调查局（U.S. Geological Survey）一直通过统计描述指标，对海底剪切应力的区域差异与沉积物活动性开展特征刻画工作。本项目旨在识别剪切应力的分布模式，为大陆架生境划界或人类开发利用决策提供参考依据。本次统计特征覆盖了从海岸至约120米水深的大陆架范围，空间分辨率约为0.04-0.06度（依纬度不同，对应5至7公里的实地距离）。研究团队通过数值模型生成波浪与环流的时间序列数据，并利用近底输出的稳态流速、振荡流速数据以及底床粗糙度估算值，以1小时间隔计算得到海底剪切应力的时间序列。随后计算得到中位数、95百分位数等统计描述指标（本数据库即包含此类输出成果），以此构建海底剪切应力区域分布模式的二维可视化图景。此外，本数据集还会将选取点位的剪切应力时间序列，与通过实测表层沉积物粒度数据计算得到的临界剪切应力值进行对比，以此估算海底沉积物的活动性。