Sentinel-1 Radiometric Terrain Corrected SAR Backscatter

Sentinel-1 Radiometric Terrain Corrected SAR Backscatter is a product processed from <a href="https://docs.sentinel-hub.com/api/latest/data/sentinel-1-grd/">Sentinel-1 ground range detected (GRD)</a> and is compliant with <a href="https://ceos.org/ard/">CEOS Analysis Ready Data for Land (CARD4L)</a> specifications for Normalised Radar Backscatter (NRB) products. CARD4L compliant products fulfill requirements for general metadata, per-pixel metadata, radiometric and atmospheric corrections and geometric corrections outlined in the NRB <a href="https://ceos.org/ard/files/PFS/NRB/v5.5/CARD4L-PFS_NRB_v5.5.pdf">product family specifications</a>. These products are processed using Sentinel Hub <a href="https://apps.sentinel-hub.com/s1-card4l/">CARD4L generation tool</a> and are radiometrically calibrated to γ° (gamma-nought) backscatter, and provided as linear backscatter power. Full radiometric terrain correction (RTC) based on the technique developed by David Small which is described in the article <a href="https://doi.org/10.1109/TGRS.2011.2120616">Flattening Gamma: Radiometric Terrain Correction for SAR Imagery</a>, has been applied using the <a href="https://docs.sentinel-hub.com/api/latest/data/dem/">Copernicus DEM</a> in order to mitigate topographic terrain effects on the backscatter induced by side-looking geometry of SAR imaging and compounded by rugged terrain. Speckle filtering has not been applied in order to preserve spatial resolution and user freedom. The twin Sentinel-1A and 1B satellites are designed to acquire data with a revisit cycle of 6 to 12 days providing continuous all-weather, day and night imagery for Land and Maritime Monitoring. This collection is comprised of CARD4L compliant Sentinel-1 VV and VH backscatter products over Africa for archived data, with new acquisitions being updated daily as they become available. To obtain CARD4L compliant Sentinel-1 data for other parts of the world, registered users have the possibility of custom processing using <a href="https://apps.sentinel-hub.com/s1-card4l/">CARD4L generation tool</a>.

哨兵-1辐射地形校正SAR后向散射产品，系由哨兵-1地面距离检测（GRD）数据加工而成，并符合CEOS陆地分析准备数据（CARD4L）规格中关于归一化雷达后向散射（NRB）产品的要求。符合CARD4L规范的产物满足通用元数据、逐像素元数据、辐射校正和大气校正以及几何校正的要求，这些要求在NRB产品系列规范中有所阐述（见<a href="https://ceos.org/ard/files/PFS/NRB/v5.5/CARD4L-PFS_NRB_v5.5.pdf">产品系列规范</a>）。这些产品通过哨兵平台CARD4L生成工具进行处理，并以γ°（伽马零）后向散射进行辐射校准，并作为线性后向散射功率提供。基于David Small所开发的技术进行的完整辐射地形校正（RTC），如其在《平缓伽马：SAR影像的辐射地形校正》一文中所述（见<a href="https://doi.org/10.1109/TGRS.2011.2120616">文献链接</a>），已利用哥白尼DEM（见<a href="https://docs.sentinel-hub.com/api/latest/data/dem/">DEM文档</a>）实施，旨在减轻由SAR成像的侧视几何形状引起的地形后向散射效应，以及复杂地形所加剧的这种效应。为了保留空间分辨率和用户自由度，未应用斑点滤波。成对的哨兵-1A和1B卫星被设计用于以6至12天的重访周期获取数据，提供全天候、昼夜连续的陆地和海洋监测影像。该数据集包括针对非洲的CARD4L规范哨兵-1 VV和VH后向散射产品，为存档数据，新获取的数据将每日更新。为了获取其他地区的CARD4L规范哨兵-1数据，注册用户可以通过<a href="https://apps.sentinel-hub.com/s1-card4l;">CARD4L生成工具</a>进行定制处理。