GCOM-W/AMSR2 L3 Sea Surface Wind Speed (1-Month,0.25 deg) dataset is obtained from the AMSR2 sensor onboard GCOM-W and produced by the Japan Aerospace Exploration Agency (JAXA). GCOM-W was launched by the H-IIA Launch Vehicle No. 21 (H-IIA F21) at 1:39 a.m. on May 18th, 2012 (Japan Standard Time, JST) and inserted into a planned position on the "A-Train" orbit. GCOM-W equipped with AMSR2 takes measurements at multiple microwave frequencies and multiple polarizations of weak electromagnetic waves in the microwave band radiated from the Earthâs surface and the atmosphere. AMSR2 has swath of 1450 km and 7 microwave bands. The observation data will enable the creation of long-term trustworthy data sets of global physical amount. The Level 3 process uses as its inputs one day's worth of Level 1B data and Level 2 data and calculates, by taking a simple arithmetic mean, the daily statistical mean value at each grid point in the specified mapping projection method (either equi-rectangular or polar stereo). Furthermore, Level 3 processing takes one month's worth of each geophysical parameter's Level 3 daily statistical mean values and calculates the monthly statistical mean value at each grid point using a simple arithmetic mean in the same way as the daily statistical mean calculation. The statistical means are calculated separately for observations along the satellite's ascending and descending tracks. This dataset includes Month Mean Sea Surface Wind Speed (SSW), Standard Deviation (Standard_Deviation), Average Number (Average_Number) and Total Number (Total_Number). Coverage of SSW is over the ocean only, and unit is [m/s]. Microwave radiometer can observe wind speed under the clouds, but it is difficult to estimate where there is rainfall and will be missing value. Wind speed around tropical cyclones, however, is important parameter in weather forecast, and we provide research product, which includes wind speed in rainy area over the ocean, as all-weather wind speed research product. Standard_Deviation is standard deviation value for each pixel. This item is only stored in monthly product. Average_Number is the number of valid physical quantity data (except error and missing) which was used to determine "Geophysical Data". Total_Number is the number of physical quantity data included in the grid (include valid and invalid). The provided format is HDF5. The Sampling resolution is 0.25degree grid. The statistical period is 1 month. The current version of the product is Version 4. The Version 3 is also available. The projection method is EQR. The generation unit is global.