Science Objectives

GPM is designed to advance scientific understanding of the Earth's water and energy cycle but will also provide near real-time data for a wide array of societal applications. As a science mission with integrated application goals, the GPM mission has five scientific objectives:

Advancing Precipitation Measurement from Space

GPM will advance precipitation measurement capability from space using a combination of active and passive remote-sensing techniques. These measurements will be used to calibrate, unify and improve global precipitation measurements by a constellation of research and operational microwave sensors. In particular, GPM will:

  • Provide measurements of microphysical properties and vertical structure information using active remote-sensing techniques over a broad spectral range
  • Measure snow and lighter rain rates through the use of high-frequency passive microwave radiometry
  • Improve passive microwave retrieval (PWR) algorithms over land
  • Improve precipitation measurements in mid- and high-latitudes during cold seasons

Improving knowledge of precipitation systems, water-cycle variability and freshwater availability

GPM will provide 4-dimensional (4-D) measurements of space-time variability of global precipitation to help to quantify regional and global water cycle processes, serving to provide a better understanding of storm structures, water/energy budget, freshwater resources, and interactions between precipitation and other climate parameters. GPM will:

  • Quantify variability of regional and global water cycle processes directly or closely related to precipitation, on diurnal through decadal time scales, based on past, present and future global precipitation datasets
  • Diagnose the rate of water transfer within Earth's atmosphere and surface while reconciling individual terms in water budget equations, as well as detect accelerations and decelerations in the global water cycle and how such accelerations respond to and influence the global climate system 
Diagram of Earth's water cycle, showing evaporation, transpiration, condensation, and preciptiation.
Illustration of Earth's water cycle.

Source: NOAA National Weather Service Jetstream

Improving climate modeling and prediction

GPM will improve climate prediction through better understanding of surface water fluxes, soil moisture storage, cloud/precipitation microphysics and latent heat release in the atmosphere to improve Earth system modeling and analysis. GPM will:

  • Understand the role of cloud-scale precipitation processes in climate sensitivity and feedback
  • Study climate system variability and climate diagnostics
  • Perform climate model simulations and reanalysis
  • Elucidate the distribution and variance of latent heat release and bulk precipitation microphysics
  • Better understand the 4-D precipitation distribution and variability from diurnal to inter-annual time scales
  • Improve datasets for climate analysis through assimilation of satellite-based precipitation information into global data assimilation systems 

Improving weather forecasting and 4-D climate reanalysis

GPM will advance numerical weather prediction (NWP) skills through more accurate and frequent measurements of precipitation-affected microwave radiances and instantaneous precipitation rates together with better quantitative error characterizations and improved weather forecasting and data assimilation systems. GPM will:

  • Improve NWP skills through assimilation of satellite-based precipitation information into numerical weather prediction systems
  • Estimate and correct systematic errors in moist processes parameterizations contained in numerical prediction models through effective use of satellite precipitation observations
  • Employ advanced assimilation methods to extract maximum information from precipitation data in the presence of forecast model errors
  • Improve the understanding and modeling of precipitation error properties
  • Monitor extreme precipitation events and freshwater availability
  • Improve position fixes for typhoon/hurricane predictions 


Visualization of Hurricane Floyd, created from NOAA GOES data.

Improving hydrological modeling and prediction

GPM will advance predictions of high-impact natural hazard events such as floods, droughts, landslides and hurricanes by providing high-resolution precipitation data through downscaling and innovative hydrological modeling. GPM will:

  • Develop hydrometeorological testbeds for evaluating the quality of satellite products in hydrological applications
  • Improve techniques for global precipitation products based on combined satellite and ground measurements
  • Quantify anticipated improvements in surface runoff, infiltration, storage, surface moisture flux transfer and other hydrological processes commonly represented in hydrometeorological models
  • Understand the quantitative nature and physical causes of differences in surface fluxes simulated by hydrometeorological models operating in different modes
  • Improve land surface data assimilation schemes for use in high resolution, nonhydrostatic, regional models, suited to availability of 3-hourly, high spatial resolution, globally available precipitation products 

Please follow the links below to learn more about Precipitation Measurement Mission science, including:

Please follow the links below to learn more about TRMM and GPM societal applications, including: