STAR Satellite Rainfall Estimates
Purpose of This Site
This page provides access to short-term rainfall products which are produced in real-time at STAR, both in image and data formats. These products are intended for use for short-term estimates of rainfall at high spatial and temporal resolution; for climate applications, we recommend other products such as CMORPH which have a higher level of accuracy but have longer latency times.
Why Use Satellite Rainfall Estimates?
Rain gauges provide a direct measurement of rainfall; however, the spatial density of rain gauge networks (especially of gauges whose data are available in real time) is typically far too coarse to capture the spatial variability of rainfall at small scales. Radar provides an indirect measurement of rainfall, but only for regions within a few hundred km of a radar unit - and even less in mountainous regions due to blockage of the beam. Estimates of rainfall from satellite data are less direct and less accurate than either gauges or radar, but have the advantage of high spatial resolution (4 km) and complete coverage over oceans, mountainous regions, and sparsely populated areas where other sources of rainfall data are not available. Since flash flood events often originate with heavy rainfall in sparsely instrumented areas that goes undetected, satellite-derived rainfall can be a critical tool for identifying hazards from smaller-scale rainfall and flood events.
The current real-time rainfall products at STAR are:
- The Hydro-Estimator (H-E), which produces estimates based on GOES IR window brightness temperatures and modifies them using numerical weather model data. The H-E has been the operational algorithm at NESDIS since 2002. It is produced operationally (24/7 support) over the CONUS, and experimentally (8/5 support) for the rest of the world.
- The GOES Multispectral Rainfall Algorithm (GMSRA), which uses four of the GOES Imager bands and also uses numerical weather model data, though to a lesser extent than the H-E. It is produced experimentally over the CONUS.
- The Self-Calibrating Multivariate Precipitation Retrieval (SCaMPR), which uses data from multiple GOES imager bands and updates its calibration in real time against microwave rainfall rates. It is produced experimentally over the CONUS.
In addition, the Hydro-Nowcaster produces forecasts of rainfall out to 3 hours lead time based on rain rates from the Hydro-Estimator.
Please refer to the corresponding product pages for additional information on these products.
In addition, the Product Validation page provides current and recent validation of 6-hour and 24-hour satellite rainfall estimates compared to rain gauges and the Stage IV radar / rain gauge field.