Special Sensor Microwave Imager/Sounder (SSMIS) Rainfall Products

Sensor Description
Algorithm Version
Input Data
Data Availability
Rainfall Data
Rainfall Images
Software
Additional Documentation/References
Related Links

Sensor Description:

The Special Sensor Microwave Imager/Sounder (SSMIS) is a conically scanning passive microwave radiometer with a 53.1 degree Earth incidence angle sensing upwelling microwave radiation at 24 channels covering a wide range of frequencies from 19 - 183 GHz. The Level 1C dataset contains only 11 of these channels, which are most relevant to sensing precipitation. Data is collected along an active scan of 144 degrees across track producing a swath width on the ground of 1707 km. The first of five sensors was launched on board DMSP F16 on October 18, 2003. The SSMIS is a joint US Air Force/Navy multi-channel passive microwave sensor that combines and extends the imaging and sounding capabilities of three seperate DMSP microwave sensors including the SSM/T, SSM/T2, and SSM/I. It was built by Northrup-Grumman Electronic Systems.

Algorithm Version:

GPR04 (GPROF Version 2004): The rainfall algorithm used to compute rainfall estimates from the SSM/I brightness temperature data is version 7 of the Goddard PROFiling algorithm (GPROF) [Kummerow et al., 2001]. Note that this version corresponds to version 6 of the GPROF algorithm applied to the TRMM TMI data.
GPR04a (GPROF Version 2004a): The rain rates in version 2004a have been adjusted to match those from the TRMM TMI. This was based on multiple years of rainfall estimates matched in space in time. The spatial and temporal matching is necessary to avoid eliminating differences resulting from diurnal variability. While the TMI samples throughout the day, the sun-synchrounous DMSP satellites sample at the same local times each day. As a result, the adjusted SSM/I rain rates will not exactly match those from TMI and they can change significantly over time as a result of satellite orbit drift.

Input Brightness Temperature Data:

The rainfall products provided here are computed from the Level 1C brightness temperature dataset.

Data Availability:

Rainfall estimates are currently available from SSMIS F16 for the period from November 20, 2005 through the present. There are currently no plans to extend this time series back to launch as the brightness temperature data prior to November 20, 2005 is not publically available.
F16 -> November 20, 2005 – Present

Rainfall Data:

Gridded daily and monthly rainfall maps have been produced for the period specified above. These data are stored as byte values in a binary data format to minimize storage/data transfer requirements and avoid byte swapping issues between different computer systems.
FTP Rainfall Data
Daily Gridded Rainfall Files Format
Monthly Gridded Rainfall Files Format

Rainfall Images:

Browse images in png format have been created for both the daily and monthly gridded rainfall data products.
Create Daily Rainfall Images
Create Monthly Rainfall Images
FTP Pre-rendered Rainfall Images

Software:

Software to read the binary data files is available in both C and IDL.
Get software

Additional Documentation/References:

– Kummerow, C., Y. Hong, W. S. Olson, S. Yang, R. F. Adler, J. McCollum, R. Ferraro, G. Petty, D. B. Shin, and T. T. Wilheit, 2001: The evolution of the Goddard profiling algorithm (GPROF) for rainfall estimation from passive microwave sensors, J. Appl. Meteor., 40, 1801-1820.