High-resolution ASCAT wind vector data set gridded by applying an optimum interpolation method to the global ocean

A new global 0.25° longitude by 0.25° latitude gridded daily wind vector data set was produced by applying an optimum interpolation method to Advanced Scatterometer (ASCAT) data as a quick recovery of the QuikSCAT/SeaWinds (QSCAT) mission that ended in November 2009. ASCAT measures the wind speed and direction over the global ocean twice a day as QSCAT did. However, the area covered by ASCAT accounts only for 60% of that covered by QSCAT during the same period because its spatial resolution measured along two parallel 550-km swaths separated by 700 km is coarser than that of QSCAT with a single 1800-km width swath along its orbit. The accuracy of gridded wind data sets constructed using ASCAT or QSCAT is therefore validated by comparing with wind data sets obtained from meteorological buoy observations. The comparisons show that both satellite wind observations agree well with the buoy observations, and the accuracy of these satellite-derived wind data sets mostly meets mission requirements (biases and root-mean square differences are less than 0.5 and 2.0 m/s, respectively) except for coastal and heavy-rain regions. In addition, intercomparison of ASCAT and QSCAT products demonstrates that the spatiotemporal wind variations derived from ASCAT are in reasonable agreement with those derived from QSCAT. Thereby, the data lost in the absence of QSCAT can be recovered using the ASCAT wind data set.