A geomorphological seabed classification for the Weddell Sea, Antarctica, with links to ArcGIS project files

Sea floor morphology plays an important role in many scientific disciplines such as ecology, hydrology and sedimentology since geomorphic features can act as physical controls for e.g. species distribution, oceanographically flow-path estimations or sedimentation processes. In this study, we provide a terrain analysis of the Weddell Sea based on the 500 m × 500 m resolution bathymetry data provided by the mapping project IBCSO. Seventeen seabed classes are recognized at the sea floor based on a fine and broad scale Benthic Positioning Index calculation highlighting the diversity of the glacially carved shelf. Beside the morphology, slope, aspect, terrain rugosity and hillshade were calculated. Applying zonal statistics to the geomorphic features identified unambiguously the shelf edge of the Weddell Sea with a width of 45-70 km and a mean depth of about 1200 m ranging from 270 m to 4300 m. A complex morphology of troughs, flat ridges, pinnacles, steep slopes, seamounts, outcrops, and narrow ridges, structures with approx. 5-7 km width, build an approx. 40-70 km long swath along the shelf edge. The study shows where scarps and depressions control the connection between shelf and abyssal and where high and low declination within the scarps e.g. occur. For evaluation purpose, 428 grain size samples were added to the seabed class map. The mean values of mud, sand and gravel of those samples falling into a single seabed class was calculated, respectively, and assigned to a sediment texture class according to a common sediment classification scheme.海底地貌在生态学、水文学、沉积学等诸多学科中均具有重要意义，因为地貌特征可作为物理控制因子，调控物种分布、海洋流路径估算以及沉积作用等过程。本研究基于国际南大洋水深制图项目（International Bathymetric Chart of the Southern Ocean, IBCSO）提供的500米×500米分辨率水深地形数据，对威德尔海开展地形分析。基于精细与粗尺度的底栖定位指数（Benthic Positioning Index）计算，研究识别出威德尔海海底共17类海底底质类型，凸显了冰川刻蚀陆架的地貌多样性。除地貌特征外，本研究还计算了坡度、坡向、地形粗糙度与山体阴影等地形参数。通过对已识别地貌特征应用分区统计分析，研究明确界定了威德尔海的陆架边缘：其宽度为45~70千米，平均水深约1200米，水深范围介于270米至4300米之间。沿陆架边缘分布有一条长约40~70千米的地貌带，该带内发育复杂多样的海底地貌，包括海槽、平坦海岭、尖峰、陡坡、海山、露头与窄海岭，此类地貌结构的宽度约为5~7千米。本研究厘清了崖壁与凹陷调控陆架与深渊区连通性的空间位置，以及崖壁内部倾角高低变化的分布情况。为开展评估验证，本研究将428份沉积物粒度样品纳入海底底质分类图中。研究分别计算了归入单类海底底质的所有样品的泥质、砂质与砾石组分平均含量，并依据通用沉积物分类方案，将其划归至对应的沉积物结构类型。