ATMS Rainfall Rate
Frequently Asked Questions about the ATMS Rainfall Rate Product
1) What is this product?
This product outputs instantaneous rainfall rates from the S-NPP and JPSS satellites in mm/hr. It is useful when trying to identify rainfall rates at specific locations, especially data-denied areas. Comparing these rainfall rates to those estimated by radars, geostationary satellites, and rain guages will give forecasters a more complete understanding of the overall precipitation that has fallen. In addition, it allows for identification of the areas of heaviest rainfall when other sources of ground-truth are unavailable. This can inform decisions regarding flash flooding.
2) How often do I receive this data?
The S-NPP satellite is part of the Afternoon Train (A-Train) of satellites. It crosses your area at ~1:30am and ~1:30pm local time every day.
3) How do I display this product in AWIPS-II?
4) How do I interpret the color maps associated with this product?
5) What should I use in conjunction with this product to produce a better forecast?
Geostationary satellite rainfall estimates, other polar-orbiting satellite rainfall estimates (if they sample the same area in a reasonable timeframe), radar-estimated rainfall, and ground-truth surface observations (rain guages, etc.)
6) How is this product created?
The Advanced Technology Microwave Sounder (ATMS) on board the S-NPP and JPSS satellites produces a Rainfall Rate product. This product is created through the Microwave Integrated Retrieval System (MIRS), which uses the same algorithm for several polar-orbiting satellite microwave sensors. This product is based on the physical relationship found between the amounts of hydrometeoros in the atmosphere (cloud liquid water, rain water, and ice water path) and surface rainfall rate. The algorithm uses a multi-linear regression approach that requires hydrometeor products, and a set of regression coefficients corresponding to each hydrometeor in order to retrieve instantanteous rainfall rate in mm/hr.1
During the development of the proposed technique, it was found that RWP and IWP were the two hydrometeors that maintained the largest correlation with respect to the surface rain rate. In essence, the MiRS precipitation technique estimates surface rainfall rate by capturing signatures from both energy emitted (and scattered in the case of rain) by cloud liquid and raindrops (through the use of cloud liquid and rain water path), as well as energy mainly scattered by ice particles (by means of the ice water path). The regression coefficients used in this calculation have been determined based on an off-line training using collocated sets of rainfall rate and hydrometeors, both coming from the fifth-generation Pennsylvania State University and the National Center for Atmospheric Research Mesoscale Model (MM5) data for the ocean surface type. For the land surface type, the regression coefficients have been derived using surface rainfall rate retrieved by the operational Microwave Surface and Precipitation Products System (MSPPS) and hydrometeors retrieved by MiRS. For the computation of the regression coefficients, precipitation cases during the warm and winter seasons were selected in order to provide information over different seasons to the regression coefficients.1
1 Flavio Iturbide-Sanchez, Sid-Ahmed Boukabara, Ruiyne Chen, Kevin Garrett, Christopher Grassotti, Wanchun Chen, and Fuzhong Weng. Assessment of a Variational Inversion System for Rainfall Rate over Land and Water Surfaces, IEEE Transaction on Geosciences and Remote Sensing, Vol 20, No. 20, 2011. http://mirs.nesdis.noaa.gov/publications/IEEE_TGARS_MiRS_Precipitation_Final_v0.1.pdf