Presenter: Naoto Ebuchi (Hokkaido University)

Description:
JAXA produced the all-weather sea surface wind (ASW) product based on AMSR2 7 and 10 GHz brightness temperatures to avoid contaminations due to heavy rain and provides data under extreme wind speed conditions, such as tropical cyclones. Spatial resolution of the product is 50 km. The AMSR2 ASW product was evaluated using data obtained around hurricanes by the airborne Stepped-Frequency Microwave Radiometers (SFMR), which were calibrated with dropsondes measurements by NOAA/NESDIS/STAR. The SFMR wind data were smoothed along the flight track over 50 km to match with the spatial resolution of ASW product. The root-mean-square difference of the comparison between the ASW and smoothed SFMR measurements was 3.26 m/s. No systematic trends depending on wind speed or rain rate were discernible. To assess spatial distribution of high winds around tropical cyclones, the 50-kt radius derived from the ASW wind fields also compared with the typhoon best-track data. The two data sets showed reasonable agreement. It is exhibited that the ASW product has a reliable accuracy under extreme wind conditions in hurricanes and typhoons. The data will be a powerful tool for studies of air-sea interactions under tropical cyclones. JAXA is currently developing a follow-on mission, named AMSR3, which will be carried by the Global Observing SATellite for Greenhouse gases and Water cycle (GOSAT-GW). At present, it is expected to be launched in the Japanese Fiscal Year of 2023. AMSR3 succeeds all the frequency channels and polarization combinations of AMSR2. In addition, three high-frequency channels (165.5 GHz, 183±3 GHz and 183±7 GHz, V-pol) and 10.25-GHz channels (V- and H-pol) with improved Noise Equivalent Delta Temperature are added for observations of solid precipitation, humidity sounding, and high accuracy measurement of sea surface temperature. Main targets of the AMSR3 mission are producing long-term continuous data record from AMSR, AMSR-E and AMSR2 over 30 years.