This sea ice concentration dataset (SIC) was derived from the re-calibrated brightness temperature of the Microwave Radiation Imager (MWRI) sensors. The MWRI sensors are onboard the Chinese second generation of sun-synchronous meteorological satellites, i.e., FY-3A, FY-3B, FY-3C, and FY-3D, which were launched in 2008. The advanced Arctic Radiation and Turbulence Interaction Study Sea Ice (ASI) algorithm involving dynamic tie points was adopted to retrieve this SIC dataset. The MWRI-ASI SIC dataset was projected onto the polar stereographic grid true at 70 degrees at a 12.5-km spatial resolution in the Arctic and Antarctic. The time coverage of this dataset is from 12 November 2010 to 31 December 2019 with a temporary loss of 23 days in the Arctic and 82 days in the Antarctic. The MWRI-ASI SIC dataset is achieved in TIFF format. The data values have specific meanings: '0-100' for the percentage of SIC, '-1' for land, '-2' for the Pole Hole, and 'NoData' for missing data. The accuracy of this dataset was assessed by ship-based observational SIC. A total of 8887 and 3882 samples of SIC observations were used in the Arctic and Antarctic, respectively. The differences between this MWRI SIC and ship-based SIC are concentrated from -20% to 20% with the overall mean absolute deviation of 16.1% in the Arctic and 17.1% in the Antarctic, respectively. The treads of sea ice extent obtained from this MWRI-ASI SIC for both Arctic and Antarctic are consistent with those from the Sea Ice Index provided by the Ocean and Sea Ice Satellite Application Facility Norwegian Meteorological Institute (OSI-SAF) and the NASA National Snow and Ice Data Center (NSIDC). This dataset can be considered as an important backup of sea ice concentration or extent passive microwave products for multidisciplinary studies in the polar regions and beyond.

The SIC dataset contains 6569 SIC files in TIFF format, 3314 of which are in the Arctic and 3255 of which are in the Antarctic. The size of all files is about 2 GB.The naming convention of SIC files is “FY_MWRI_SIC_DAILY_YYYYMMDD_Region.tif”, among which “YYYYMMDD” is the date and “Region” is the Arctic or Antarctic.The dataset also provides two error products. One is the bias between this MWRI-ASI SIC and SIC derived from the Special Sensor Microwave Imager (SSMI) series sensors using ASI algorithm, and the other is the bias between this MWRI-ASI SIC and SIC derived from the Advanced Microwave Scanning Radiometer (AMSR) series sensors using ASI algorithm. The former error product contains 6569 files in TIFF format, 3314 of which are in the Arctic and 3255 of which are in the Antarctic. Due to a data gap of the AMSR series sensors from 2011 to 2012, the latter error product contains 6014 files in TIFF format, 3034 of which are in the Arctic and 2980 of which are in the Antarctic.The naming convention of SIC error files is “SIC_Bias_MWRI-ASI_XXXX-ASI_YYYYMMDD_Region.tif”, among which “XXXX” is the SSMI or AMSR, “YYYYMMDD” is the date and “Region” is the Arctic or Antarctic.