[A-CG37] Satellite Earth Environment Observation

[ACG37-16] Long-term Global Water Cycle Observations by the GCOM-W satellite and AMSR Series

*Misako Kachi¹, Naoto Ebuchi², Rigen Shimada¹, Keiichi Ohara¹, Hideyuki Fujii¹, Eri Yoshizawa¹, Takeshi Miura³, Kazuya Inaoka³, Yasushi Kojima³ (1.Earth Observation Research Center, Japan Aerospace Exploration Agency, 2.Institute of Low Temperature Science, Hokkaido University, 3.GOSAT-GW Project Team, Japan Aerospace Exploration Agency)

Keywords:microwave radiometer, satellite, AMSR

Space-based microwave radiometer is able to measure water-related variables inside clouds and/or ocean and land surface through clouds. Due to its frequent observation capability, data from microwave radiometer is widely used in operational applications, such as numerical weather forecast, fishery, and navigation safety, as well as scientific research on water cycle variation and climate change. JAXA has developed and operated a series of microwave radiometer, called the Advanced Microwave Scanning Radiometer (AMSR), more than 20 years. The AMSR series is a multi-frequency, total-power microwave radiometer system with dual polarization channels for all frequency bands from 6.9 to 89 GHz. The first generation of AMSR series is AMSR on ADEOS-II and AMSR-E on NASA’s Aqua launched in 2002. AMSR-E continued its scientific observations until October 2011, and after 10-month gaps, AMSR2 on the Global Change Observation Mission-Water (GCOM-W or “SHIZUKU”), the second generation, started its observation since July 2012. AMSR2 has been in extended operation phase since 2017 and continues observation more than 10.5 years in orbit with various achievements in both science and operational applications under close collaboration with the science team and stakeholders. In 2022, JAXA released new Ver.3 Precipitation product, which is consistent to the Global Satellite Mapping of Precipitation (GSMaP) Ver.5 released in December 2021, and Ver.4.1 Sea Surface Temperature (SST) product, which enables to estimate SST even under windy and/or weak-rainy conditions. We also released new research products of snow depth and soil moisture content, which are developed for future AMSR3 but cannot be processed in the current AMSR2’s mission operation system, with extension to AMSR-E to provide long-term and consistent data set.
JAXA is currently developing a follow-on mission of AMSR2, named AMSR3, to be carried by the Global Observing SATellite for Greenhouse gases and Water cycle (GOSAT-GW). As of December 2022, its launch target date is scheduled in the JFY 2024. AMSR3 is designed to succeed and expand global water cycle observations and operational applications by the past AMSR series. For this purpose, local observation time of the GOSAT-GW satellite is the same as that of GCOM-W, 13:30 in ascending orbit, and sensor specification of AMSR3 is almost similar to that of AMSR2 except additional channels in high-frequency (166.5, 183+-7, 183+-3 GHz) for snowfall and water vapor analysis and 10.25 GHz with improved NEDT for robust SST retrievals in higher spatial resolution. Since AMSR2 is in healthy condition, we expect overlap observation between AMSR2 and AMSR3 for cross calibration to provide more precise and consistent long-term dataset, the Climate Data Record (CDR) of AMSR series.
Further information regarding the AMSR series can be obtained from the integrated web site for the AMSR series (https://www.eorc.jaxa.jp/AMSR/).