AMSR3, the Advanced Microwave Scanning Radiometer 3 onboard the Global Observing SATellite for Greenhouse gases and Water cycle GOSAT-GW (“IBUKI GW”), has begun delivering early observation data following its June 29, 2025 launch and orbit insertion on July 20. JAXA reports the instrument’s antenna is rotating at 40 rpm for stable scanning, with data acquisition underway since August 11 as part of initial functional verification.
New channels expand precipitation and humidity sensing
AMSR3 extends the heritage of AMSR-E (Aqua, 2002) and AMSR2 (GCOM-W, 2012) with added sensitivity and frequency coverage. Five new channels—10.3 GHz (V- and H-pol) and V-pol at 165.5, 183.3±7, and 183.3±3 GHz—enable detailed detection of high-latitude snowfall and retrieval of atmospheric water vapor profiles. The 10 GHz additions improve temperature resolution and reduce noise for more robust sea surface temperature (SST) retrievals at higher spatial resolution.
- High-frequency channels (165.5 and 183.3 GHz) improve sensitivity to ice particles in clouds and surface snowfall.
- Enhanced 10.3 GHz channels strengthen SST products used in fisheries and marine applications.
- Continuity of long-term records supporting weather, ocean, cryosphere, and climate monitoring.
Early imagery highlights global clouds, Arctic snowfall, and SST patterns
Initial composites showcase global cloud and precipitation distributions, aided by 165.5 GHz sensitivity to upper cloud ice. An Arctic-focused composite demonstrates differentiation between ice-dominated clouds and rain systems, supporting snowfall identification in high latitudes. AMSR3’s ~1,500 km swath provides near-global coverage (99.9%) within three days, enabling frequent updates for operational users and researchers.
Early SST maps from descending passes (August 15–17) capture cloud-obscured regions such as the tropical Pacific. Cooler SST signatures off Peru—typical of non–El Niño periods—are evident, though heavy rain and strong winds cause localized data gaps. These observations underscore the instrument’s capability to deliver day–night, all-weather SST coverage.
Sea ice monitoring and climate continuity
AMSR3 extends satellite-based microwave monitoring of polar sea ice, which has continued since 1978. Early maps illustrate Arctic summer minimum conditions and widespread Antarctic winter extent. The AMSR series has contributed to decades-long, high-resolution sea ice records, with prior results indicating substantial summer Arctic sea ice decline. AMSR3 is designed to sustain and refine these climate data records with expanded channel capabilities.
Roadmap to calibrated products
JAXA, working with prime contractor Mitsubishi Electric and partner companies, is conducting a three-month on-orbit verification to confirm nominal satellite and instrument performance. Subsequent phases will emphasize calibration and validation of geophysical products. Product accuracy will be cross-checked against AMSR2 and integrated into JAXA’s Global Satellite Mapping of Precipitation (GSMaP) system, which will assimilate AMSR3 inputs to improve global precipitation estimates.
What AMSR3 measures
By sensing naturally emitted and scattered microwaves across 21 channels from 6.9 to 183.3 GHz, AMSR3 targets a broad set of water-related parameters, including:
- Precipitation (rain and snow)
- Sea surface temperature and sea surface wind speed
- Soil moisture and snow depth
- Sea ice concentration
- Cloud ice and water signatures, and atmospheric water vapor
These data support applications in weather forecasting, ocean operations, ship navigation safety, and climate and water cycle research.
Source: JAXA press release
