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Space-based microwave imagers with low-to-high frequency channels are a strong tool for monitoring water-related variables inside of clouds and Earth's surface through clouds on a daily basis. The Advanced Microwave Scanning Radiometers (AMSR) are a series of Japanese microwave imagers that have unique capabilities in their high spatial resolution with large-sized main reflector, dual polarization channels for all frequency bands from 6.9- to 89-GHz, and frequent global observation with wide swath. The series of instruments provide continuous global water cycle observations for more than 23 years by AMSR-E on board the NASA's Aqua satellite launched in 2002 and AMSR2 on board the Global Change Observation Mission - Water (GCOM-W) launched in 2012 and currently in operation. Data from the AMSR series is widely used in meteorological agencies in Japan, U.S., Europe, Australia, etc., and is also used for monitoring of sea ice in polar oceans. It also contributes to producing satellite based merged precipitation products, such as GSMaP, IMERG, CMORPH, etc., to monitor hourly global rainfall distribution in a near-real-time basis.
The latest instrument, AMSR3 on board the Global Observing SATellite for Greenhouse gases and Water cycle (GOSAT-GW) launched in June 2025, succeeds the afternoon orbit observation of AMSR2, and expands its observation capability to respond to new user needs. Major improvements in AMSR3 are new high-frequency channels (166- & 183-GHz) for snowfall retrievals and water vapor analysis in numerical weather predictions, and additional 10.25-GHz channels with better Noise Equivalent Delta Temperature (NEDT) for robust sea surface temperature estimates.
In this session, we will focus on the observation results and outcomes obtained by the past and current AMSR series, and early observation, calibration, and validation results from AMSR3.