Arctic daily 1km sea ice drift product: 2018-2020, version 1.0

“The Arctic daily 1 km sea ice drift product: 2018-2020, version 1.0” is generated by the School of Geospatial Engineering and Science at Sun Yat-Sen University, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai) and Polar Science Center at Sun Yat-Sen University. This product provides the Arctic daily high spatial resolution (1 km) sea ice drift information over 2018-2020 in netcdf format (.nc). One netcdf file (i.e. daily sea ice drift data) consists of 4 layers, including the geographic coordinates (longitude and latitude information) and the sea ice drift speed (unit: km/d) at the x and y directions under the EPSG: 3408 coordinate system (i.e. NSIDC_EASE_Grid_North coordinate system) of each 1km grid.This product is generated by using multi-source datasets, including the medium and high spatial resolution SAR and optical remotely sensed data (i.e. Sentinel-1 A/B and MODIS Terra/Aqua images) and Polar Pathfinder Daily 25 km EASE-Grid Sea Ice Motion Vectors, version 4 (referred to as NSIDC-Pathfinder hereafter) provided by National Snow and Ice Data Center (NSIDC). In total, 118,359 Sentinel SAR images and 56,857 MOIDS images are used. The product process mainly includes three procedures: First, Sentinel-1 SAR images in the sea ice freezing season and MODIS images in the melting season are preprocessed with geocoding, resampling and etc. Then, the image pairs are created based on transit time and spatial overlap information. The feature tracking sea ice vectors are retrieved from the image pairs based on the A-KAZE algorithm and bad matches filtering. Finally, the merged Arctic daily 1km sea ice drift fields are generated based on co-kriging method with the feature tracking results as the main variable and the NSIDC-Pathfinder as the covariable (i.e. background field).A preliminary validation is conducted on this product over 2018-2020 using the IABP (International Arctic Buoy Programme) buoy data, and a total of 31,194 valid verification results are received. The sea ice drift velocity MAE (Mean Absolute Error) of this product is 1.08 km/d, and the angle MAE is 9.63 °. Compared to the mainstream sea ice drift products (showing 10-100km spatial resolution with the speed and angle MAE around 1.5km/d and 20°, respectively), this product shows advantages in both spatial resolution and accuracy.