# GPM IMERG
*data products*

## Specifications
- **level**: L3
- **distributor**: nasa
- **file format**: NetCDF4 / HDF5 / GeoTIFF
- **access model**: open
- **cost model summary**: free (registered NASA Earthdata login)
- **primary data portal url**: https://gpm.nasa.gov/data/imerg
- **use cases**: ["Global precipitation monitoring and mapping at half-hourly to monthly accumulations","Flood and drought early-warning support","Hydrological and land-surface model forcing input","Climate research and precipitation trend analysis using the merged TRMM+GPM multi-decadal record"]
- **practical limitations**: ["Passive-microwave/IR-derived rain rates carry higher uncertainty over complex terrain, coastal zones, and snow/ice surfaces","Final Run gauge-calibrated output lags the near-real-time Early (about 4 hours) and Late (about 14 hours) runs by roughly 2.5 months"]
- **deployment context**: orbital
- **entity type**: data_product
- **last verified date**: 2026-09-29
- **verified by**: agency-doc
- **claim status**: agency-sourced
- **provider**: nasa

## Editorial
GPM IMERG (Integrated Multi-satellitE Retrievals for GPM) is a Level 3 precipitation data product distributed by NASA, merging measurements from the Global Precipitation Measurement (GPM) satellite constellation into a single gridded estimate of global rainfall and snowfall.[^imerg-nasa-overview] The product is calibrated against the GPM Core Observatory, the constellation's reference satellite, and combines passive-microwave and infrared-derived rain-rate estimates from the wider constellation to produce precipitation fields at accumulation intervals ranging from half-hourly to monthly.[^gpm-core-observatory-overview]

IMERG is issued in three processing runs with different latency and accuracy tradeoffs. The near-real-time Early Run half-hourly product is available approximately 4 hours after observation time, and the Late Run follows at roughly 14 hours; the gauge-calibrated Final Run, adjusted against ground-based rain-gauge networks, lags the near-real-time runs by around 2.5 months.[^imerg-ges-disc-half-hourly] NASA distributes the data in NetCDF4, HDF5, and GeoTIFF formats at no cost, subject to NASA Earthdata login registration.[^imerg-nasa-overview]

Use cases include global precipitation monitoring and mapping at half-hourly to monthly accumulations, flood and drought early-warning support, hydrological and land-surface model forcing input, and climate research drawing on the merged TRMM and GPM multi-decadal precipitation record.[^imerg-nasa-overview] Passive-microwave and infrared-derived rain-rate retrievals carry higher uncertainty over complex terrain, coastal zones, and snow or ice-covered surfaces, a limitation relevant to near-real-time use of the Early and Late runs in those settings.[^imerg-ges-disc-half-hourly]

## Supply chain position
- gpm-core-observatory (missions) --[data_products_from_missions]--> GPM IMERG

## Sources
- [imerg-nasa-overview] | IMERG (Integrated Multi-satellitE Retrievals for GPM), NASA GPM mission | https://gpm.nasa.gov/data/imerg | tier=agency-doc | accessed=2026-09-29
- [imerg-ges-disc-half-hourly] | IMERG Early Run 30-minute product, GES DISC / NASA GPM | https://gpm.nasa.gov/node/2525 | tier=agency-doc | accessed=2026-09-29
- [gpm-core-observatory-overview] | Global Precipitation Measurement (GPM) mission overview, NASA | https://gpm.nasa.gov/missions/GPM | tier=agency-doc | accessed=2026-09-29

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Source: https://eo-atlas.org/data_products/gpm-imerg
Maintainer: SpectraWorks B.V. (CC-BY 4.0)