The Global Precipitation Measurement (GPM) mission is an international network of satellites that provide next-generation global observations of rain and snow. Led by NASA and the Japan Aerospace Exploration Agency (JAXA), GPM builds upon the legacy of the Tropical Rainfall Measuring Mission (TRMM) to set a new standard for precipitation measurements from space.

Overview of the GPM Mission

The GPM mission concept centers on a Core Observatory satellite carrying advanced instruments to measure precipitation from space. Launched in 2014, the GPM Core Observatory serves as a reference standard to unify precipitation measurements from a constellation of research and operational satellites provided by international partners.

Key features of the GPM mission include:

• Provides global precipitation measurements every 3 hours, with improved accuracy and coverage.
• Measures light to heavy rain, falling snow, and ice particles in clouds and storms.
• Tracks hurricanes and tropical cyclones, and monitors floods and landslides.
• Improves weather forecasting and climate research around the world.

Advanced Instrumentation

The GPM Core Observatory carries a multi-frequency radar and radiometer system called the GPM Microwave Imager (GMI). GMI has 13 microwave channels ranging in frequency from 10 GHz to 183 GHz, giving it the ability to detect light and solid precipitation.

The Dual-frequency Precipitation Radar (DPR) on the GPM Core Observatory consists of a Ku-band radar (13.6 GHz) and a Ka-band radar (35.5 GHz). The Ku-band radar scans a 245 km swath, while the Ka-band radar focuses on a narrower 120 km swath to provide detailed 3D views of precipitation structures.

International Satellite Constellation

The GPM constellation consists of 9 additional satellites with microwave radiometers provided by NASA, NOAA, the European Space Agency, the French space agency CNES, the Indian Space Research Organization, and JAXA. GPM inter-calibrates and unifies data from the constellation satellites to expand coverage and provide near-global precipitation measurements every 3 hours.

Applications and Benefits

The high-quality data provided by GPM is used by government agencies, weather forecasters, and researchers worldwide. Key applications include:

• Tracking hurricanes and cyclones like typhoons in the Pacific Ocean.
• Monitoring flood and landslide hazards associated with extreme precipitation events.
• Improving numerical weather prediction models by assimilating GPM precipitation data.
• Enhancing hydrological predictions of droughts, freshwater resources, and flood risks.
• Advancing understanding of Earth’s water and energy cycles and climate variability.

Data Products and Availability

GPM data products are freely available and provide precipitation rates, types, and particle sizes across the globe. Key products include:

• The IMERG dataset which combines observations from GPM constellation satellites to estimate precipitation every 30 minutes.
• The DPR dataset which provides 3D views of precipitation structures from the GPM Core Observatory.
• Snowfall detection products for tracking solid precipitation.
• Hurricane and tropical cyclone track datasets.

GPM data can be accessed through NASA’s Precipitation Processing System and the Goddard Earth Sciences Data and Information Services Center.

Summary

With nearly 20 years of spaceborne precipitation measurements, GPM provides an unprecedented view of global precipitation for weather forecasting, climate research, and studying extreme events like floods, landslides, and storms. The next-generation instruments on the GPM Core Observatory set a new standard for detecting rain and snow worldwide.