Visualization of the GPM Core Observatory in space over a hurricane with constellation satellites in the background.

The Global Precipitation Measurement Mission (GPM)

Image

GPM Mission Concept

The Global Precipitation Measurement (GPM) mission is an international network of satellites that provide next-generation global observations of rain and snow. Building upon the success of the Tropical Rainfall Measuring Mission (TRMM), the GPM concept centers on the deployment of a “Core Observatory” satellite carrying an advanced radar / radiometer system to measure precipitation from space and serve as a reference standard to unify precipitation measurements from a constellation of research and operational satellites. Through improved measurements of precipitation globally, the GPM mission is helping to advance our understanding of Earth's water and energy cycles, improve forecasting of extreme events that cause natural hazards and disasters, and extend current capabilities in using accurate and timely information of precipitation to directly benefit society. GPM, initiated by NASA and the Japan Aerospace Exploration Agency (JAXA) as a global successor to TRMM, comprises a consortium of international space agencies, including the Centre National d’Études Spatiales (CNES), the Indian Space Research Organization (ISRO), the National Oceanic and Atmospheric Administration (NOAA), the European Organization for the Exploitation of Meteorological Satellites (EUMETSAT), and others.

The GPM Core Observatory launched on February 27th, 2014 at 1:37pm EST from Tanegashima Space Center, Japan. Learn more about the launch.

Building upon TRMM’s Legacy

The Tropical Rainfall Measuring Mission (TRMM), launched by NASA and JAXA in 1997, used both active and passive microwave instruments to measure rainfall in the tropics. It also provided a foundation for merging rainfall information from other satellites. TRMM showed the importance of taking observations from a non-Sun-synchronous orbit at different times of the day, between observations by polar orbiting sensors at fixed times of the day, to improve near real-time monitoring of hurricanes and accurate estimates of rainfall accumulation over time. The GPM Core Observatory continues this sampling from a non-Sun-synchronous orbit and extends coverage to higher latitudes to provide a near global view of precipitation.

The GPM Core Observatory design is an extension of TRMM’s highly successful rain-sensing package, which focused primarily on heavy to moderate rain over tropical and subtropical oceans. Since light rain and falling snow account for significant fractions of precipitation occurrences in middle and high latitudes, a key advancement of GPM over TRMM is the extended capability to measure light rain (< 0.5 mm hr-1), solid precipitation and the microphysical properties of precipitating particles. This capability drives the designs of both the active and passive microwave instruments on GPM. The Core Observatory acts as a reference standard for the precipitation estimates acquired by the GPM constellation of sensors.

GPM Core Observatory Satellite

The GPM Core Observatory carries the first space-borne Ku/Ka-band Dual-frequency Precipitation Radar (DPR) and a multi-channel GPM Microwave Imager (GMI). The DPR instrument consists of a Ka-band precipitation radar (KaPR) operating at 35.5 GHz and a Ku-band precipitation radar (KuPR) operating at 13.6 GHz. DPR provides three-dimensional measurements of precipitation structure and characteristics. The DPR originally collected data over a swath of 78 and 152 miles (125 and 245km)  for the Ka and Ku band radars respectively, but since May 2018 the swath now covers 152 miles (245 km) for both radars.  Relative to the TRMM precipitation radar, the DPR is more sensitive to light rain rates and snowfall. In addition, simultaneous measurements by the overlapping of Ka/Ku-bands of the DPR can provide new information on particle drop size distributions over moderate precipitation intensities. In addition, by providing new microphysical measurements from the DPR to complement cloud and aerosol observations, GPM is expected to provide further insights into how precipitation processes may be affected by human activities.

The GMI instrument is a conically-scanning multi-channel microwave radiometer covering a swath of 550 miles (885 km) with thirteen channels ranging in frequency from 10 GHz to 183 GHz. The GMI uses a set of frequencies that have been optimized over the past two decades to retrieve heavy, moderate and light precipitation using the polarization difference at each channel as an indicator of the optical thickness and water content and precipitation systems.

Image

This diagram illustrates the dimensions covered by the GPM Core Observatory's Dual-frequency Precipitation Radar (DPR) and GPM Microwave Imager (GMI) instruments. NOTE: As of May 2018 the KaPR swath width is now also 245km. Last updated on March 20, 2024. 

IMERG: Two Decades of Global Precipitation Data

NASA’s TRMM and GPM missions have collected rain and snowfall from space for more than 22 years (as of 2020), and for the first time in 2019 scientists can access PMM’s entire record as one unified data set. The Integrated Multi-satellitE Retrievals for GPM (IMERG) algorithm combines information from whatever constellation of satellites are operating around Earth at a given time to estimate precipitation over the majority of the Earth's surface.  This algorithm is particularly valuable over the majority of the Earth's surface that lacks precipitation-measuring instruments on the ground.  What is new in the latest Version 6 release of IMERG is that the algorithm can now fuse the early precipitation estimates collected in 2000-2014 during the operation of the TRMM satellite with more recent precipitation estimates collected during operation of the GPM satellite.  The longer the record, the more valuable it is, as researchers and application developers will attest. By being able to compare and contrast past and present data, researchers are better informed to make climate and weather models more accurate, better understand normal and extreme rain and snowfall around the world, and strengthen applications for current and future disasters, disease monitoring, resource management, energy production and food security.

More GPM IMERG resources

GPM Science and Applications

GPM provides global precipitation measurements with improved accuracy, coverage and dynamic range for studying precipitation characteristics. GPM also improves weather and precipitation forecasts through assimilation of instantaneous brightness temperatures and retrieved precipitation information. Relative to TRMM, the enhanced measurement and sampling capabilities of GPM offer many advanced science contributions and societal benefits:

Learn more about GPM's science objectives

Learn more about GPM's applications

Related Articles
GPM 10-in-10 Banner showing the GPM satellite over Earth sensing precipitation.
Have you ever wondered how Earth observing satellites are able to measure things like precipitation, temperature, and other phenomenon from space? Join us during this free webinar to learn about “remote sensing” and gain an understanding of how and why we use satellites to help us understand and protect our home planet.
GPM 10-year banner
Too little or too much precipitation can mean the difference between life and death. Join us as we learn about the impacts of having too much or too little precipitation and the disasters that can occur as a result. Discover what we are learning about the connection between extreme weather events and climate change. Find out the many ways that NASA is helping us monitor and respond to natural hazards and disasters.
GPM 10-in-10 Climate Banner
May 9, 2024, 8:00 p.m. ET Overview In this webinar we will explore Earth’s weather and climate through the lens of NASA. Learn the difference between weather and climate, why it’s challenging to accurately predict the weather, and explore different weather and climate models. Also, learn how NASA’s “Earth to Sky” program is engaging with interpreters across the U.S. to collaborate and share this and other information with the public. Resources Resource Packet Speakers Dr. Marshall Shepherd Dr. J. Marshall Shepherd is a leading international weather-climate expert and is the Georgia Athletic
GPM 10-in-10 Earth's water banner
March 14, 2024, 8 p.m. ET Overview On March 22 we celebrate World Water Day! For the next in our GPM 10-in-10 webinar series, join NASA scientists to learn all about freshwater, Earth’s most precious resource. Find out how and why NASA keeps track of Earth's limited freshwater resources and discover how you can monitor precipitation yourself as a citizen scientist working with CoCoRaHS and the GLOBE Program . Guest speakers include John Bolten, Chris Kidd, Noah Newman, Marilé Colón Robles, and Dorian Janney. Resources Webinar 2 Recording Resource Packet About the Speakers John Bolten John is
GPM 10 Year Banner
Celebrate the Global Precipitation Measurement Mission's 10th Anniversary! The NASA / JAXA GPM Core Observatory satellite launched on Feb. 27, 2014 from Tanagashima Space Center in Japan, marking the start of the Global Precipitation Measurement mission . We will celebrate this ten-year anniversary throughout 2024 with special events and opportunities. We invite all of you to join us as we share how this international constellation has improved life around the globe. About GPM The GPM Mission & Core Observatory Satellite GPM Applications & Societal Benefits IMERG - A Global Map of Earth's Rain
GPM Core Observatory data of precipitation within Typhoon Mawar
Driven by powerful winds and intense rainfall, Typhoon Mawar emerged as a rapidly intensifying storm in the western Pacific Ocean. Originating from a tropical disturbance, the typhoon swiftly developed into a significant weather system, eventually making landfall on the U.S. territory of Guam on May 25, 2023, as a Category 4 typhoon. After hitting Guam, it further intensified into a Category 5 typhoon, making it one of the most powerful storms on record in the month of May. Download this video from the NASA Goddard Scientific Visualization Studio The combination of NASA’s IMERG precipitation
20 Years of IMERG - Resources
NASA Announces Long-term IMERG Satellite Record: A Near-Global 19-year Perspective on Rain and Snow NASA has just released its newest estimate of rain and snow covering the past 19 years. It's code name: Version 6 IMERG. NASA's IMERG -- the Integrated Multi-satellitE Retrievals for GPM -- combines information from whatever constellation of satellites are operating in Earth orbit at a given time, to estimate precipitation over the majority of the Earth's surface. This algorithm is particularly valuable over the majority of the Earth's surface that lacks precipitation-measuring instruments on...
Two Decades of Precipitation Measurement
NASA’s Precipitation Measurement Missions (PMM) have collected rain and snowfall from space for nearly 20 years, and for the first time in 2019, scientists can access PMM’s entire record as one data set. PMM includes two missions – the Tropical Rainfall Measuring Mission (TRMM), which orbited Earth from 1997 to 2015, and its successor, the joint NASA-JAXA Global Precipitation Measurement mission (GPM), which has been collecting data since 2014. This year, however, the GPM project upgraded its data algorithms to calibrate and incorporate TRMM data into its release, giving researchers, modelers...
5 Years of Global Precipitation Measurement
Download this video in high resolution from the NASA Goddard Scientific Visualization Studio Five years ago, on Feb. 27, 2014, the Global Precipitation Measurement (GPM) Core Observatory, a joint satellite project by NASA and the Japan Aerospace Exploration Agency (JAXA), lifted off aboard a Japanese H-IIA rocket. Since then, the cutting-edge instruments on GPM have provided advanced measurements about the rain and snow particles within clouds, Earth’s precipitation patterns, extreme weather and myriad ways precipitation around the world affects society. Among the uses of GPM data are helping...
GPM Applications Logo
For the past 5 years GPM data has provided critical information to end-users to further our understanding of Earth's water cycle and to facilitate decision‐making at local and global scales. Building on the legacy of TRMM, the use of high‐quality precipitation data provided by GPM, with global coverage, has enabled new science research and data applications to benefit society across a diverse range of applications including water resource and ecological management, operational numerical weather prediction, disease prediction, and disaster modeling and response. Here are five highlights of the...

Hide Date