IWWOC Antarctic Sea Ice Backscatter Gridded Level 3 Composite from SCAT onboard CFOSAT

Backscatter values over sea ice are a function of incidence angle and the sea ice type. With several SCAT incidence measurements, an incidence adjustment is mandatory over sea ice (Gohin and Cavanié 1994) to map daily averaged backscatter values accurately for geophysical use as it was done for the NSCAT Ku-band sensor. An incidence-adjustment backscatter map at 40° incidence angle is thus built in order to have reliable daily averaged backscatter maps. This dataset contains antarctic polar stereographic 12 km resolution grids of averaged backscatter coefficient from SCAT onboard CFOSAT scatterometer over sea-ice, for each polarization (HH and VV). CFOSAT (Chinese French Ocean SATellite) is a french-chinese mission launched in 2018, whose aim is to provide wind (SCAT instrument) and wave (SWIM instrument) measurements over the sea surface. The grids are derived from swath sigma-naught data (CWWIC SCAT Level 1A product), averaged over one day. Sea ice roughness from the scatterometer backscatter can be used later for sea ice type detection (multi-year ice, first-year ice), sea ice edge (by discriminating open water from sea-ice) and later sea ice displacement maps . In the case of CFOSAT, the HH and VV polarization ratio can be used for sea ice studies, in particular sea ice edge criteria and ice type classification. Access to the data is free and open. In order to be informed about changes and to help us keep track of data usage, we encourage users to register at: https://forms.ifremer.fr/lops-siam/access-to-iwwoc-cfosat-data/ This dataset is generated and distributed by Ifremer / CERSAT in the frame of the Ifremer Wind and Wave Operation Center (IWWOC) co-funded by Ifremer and CNES and dedicated to the processing of the delayed mode data of CFOSAT mission.

海冰的后向散射值是入射角与海冰类型的函数。当获取多组散射计（SCAT）入射角测量数据后，对海冰开展入射角校正是必要的（Gohin与Cavanié，1994），以此精准生成可用于地球物理研究的日平均后向散射值，正如NSCAT Ku波段传感器所采用的处理流程。为此，我们构建了入射角校正至40°的后向散射图，以获得可靠的日平均后向散射图集。本数据集包含由中法海洋卫星（CFOSAT，Chinese French Ocean SATellite）搭载的SCAT散射计获取的海冰后向散射系数日平均格网数据，采用南极极球面投影（antarctic polar stereographic），分辨率为12 km，涵盖HH与VV两种极化方式。CFOSAT是2018年发射的中法合作航天任务，其核心目标是通过SCAT仪器获取海面风场数据、通过SWIM仪器获取海面浪场数据。该格网数据源自条带幅归一化后向散射系数（sigma-naught，σ⁰）数据（CWWIC SCAT Level 1A产品），经单日时长的平均处理后得到。通过散射计后向散射数据反演得到的海冰粗糙度，可用于后续多项海冰相关研究：包括海冰类型识别（区分多年冰与一年冰）、海冰边缘提取（通过区分开阔水域与海冰）以及海冰位移图生成。针对CFOSAT数据，HH与VV极化比可进一步应用于海冰研究，特别是海冰边缘判定与冰型分类任务。本数据集免费开放获取。为便于我们跟踪数据使用情况并及时告知数据更新信息，我们鼓励用户在以下网址完成注册：https://forms.ifremer.fr/lops-siam/access-to-iwwoc-cfosat-data/。本数据集由法国海洋开发研究院（Ifremer）/海洋环境与卫星研究中心（CERSAT）在法国海洋开发研究院风浪作业中心（IWWOC，Ifremer Wind and Wave Operation Center）的框架下生成并分发，该中心由Ifremer与法国国家空间研究中心（CNES）共同资助，专门负责处理CFOSAT任务的延迟模式数据。