IWWOC Arctic 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 Arctic 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。借助多组散射计（SCAT）的入射角测量数据，对海冰开展入射角校正是必不可少的环节（Gohin与Cavanié，1994），以便精准生成适用于地球物理应用的日平均后向散射值，正如NSCAT Ku波段传感器所采用的处理方案。因此，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CFOSAT（中国-法国海洋卫星，Chinese French Ocean SATellite）搭载的SCAT散射计在海冰区域获取的、经日平均处理的后向散射系数格网数据，采用北极极射投影，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，其搭载的SCAT仪器与SWIM仪器可分别获取海面风场与海浪场测量数据。该格网数据源自条带式σ⁰（sigma-naught）数据（对应CWWIC SCAT 1A级产品），经单日平均处理得到。
后续可利用散射计后向散射反演得到的海冰粗糙度信息，开展海冰类型检测（分为多年冰与一年冰）、海冰边缘识别（通过区分开阔水域与海冰）以及海冰位移图生成等研究。针对CFOSAT数据，其HH与VV极化比可用于海冰相关研究，尤其是海冰边缘判定与冰型分类工作。
本数据集免费开放获取。为便于用户及时了解数据更新，并协助我们追踪数据使用情况，我们鼓励用户前往以下网址注册：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）/CERSAT依托法国海洋开发研究院海浪与风场作业中心（Ifremer Wind and Wave Operation Center，简称IWWOC）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CFOSAT任务延迟模式数据的处理工作。