The Advanced Microwave Scanning Radiometer 2 (AMSR2) instrument on the Global Change Observation Mission - Water 1 (GCOM-W1) provides global passive microwave measurements of terrestrial, oceanic, and atmospheric parameters for the investigation of global water and energy cycles. Near real-time (NRT) products are generated within 3 hours of the last observations in the file, by the Land Atmosphere Near real-time Capability for EOS (LANCE) at the AMSR Science Investigator-led Processing System (AMSR SIPS), which is collocated with the Global Hydrology Resource Center (GHRC) DAAC. The NRT AMSR2 Unified L3 Daily 12.5 km Brightness Temperature & Sea Ice Concentration, Version 4 uses as input the resampled brightness temperature (Level-1R) data provided by the Japanese Aerospace Exploration Agency (JAXA). The Version 4 dataset uses the AMSR-U2 product generation algorithm with slight modifications for NRT product generation, same algorithm used to generation the standard, science quality, data that is available at the NSIDC DAAC. This Level-3 gridded product includes brightness temperatures at 89.0 GHz. Data are mapped to a polar stereographic grid at 12.5 km spatial resolution. Sea ice concentration and brightness temperatures include daily ascending averages, daily descending averages, and daily averages. Data are stored in HDF-EOS5 format and are available via HTTP from the EOSDIS LANCE system at https://lance.nsstc.nasa.gov/amsr2-science/data/level3/seaice12. If data latency is not a primary concern, please consider using science quality products. Science products are created using the best available ancillary, calibration and ephemeris information. Science quality products are an internally consistent, well-calibrated record of the Earth's geophysical properties to support science. These standard product, science quality, are available at the NSIDC DAAC: https://nsidc.org/