DOI: 10.7289/v5qf8r3k
title: SSMI(S) Hydrological Products

description: The Special Sensor Microwave/Imager (SSM/I) and Special Sensor Microwave Imager-Sounder (SSMIS) have been making measurements of earth-emitted microwave radiation for over two decades. Antenna temperature data from these sensors are used to derive both atmospheric and surface hydrological parameters and to generate these global monthly mean products. Specifically, this includes monthly or 5-day estimates of rainfall and its frequency, cloud liquid water and cloud frequency, water vapor, liquid water path, snow cover frequency, satellite sampling frequency and various imagery. The data collection consists of five different products: the Monthly 2.5 Degree Gridded Dataset, the Monthly 1.0 Degree Gridded Dataset, the Pentad 2.5 Degree Gridded Dataset, Imagery, and specially formatted files used in the Global Precipitation Climatology Project Dataset (GPCP). All data in this collection (except the Pentad and Imagery datasets) extend from July 1987 until present. 

Monthly 2.5 Degree Gridded Dataset
Products included in this domain are taken from early orbits and include: mean cloud fraction (cfr), mean sea-ice cover (ice), liquid water path (lwp), mean rain fraction (pf2), rainfall (pr1), snow cover fraction (snw), mean sampling fraction (ssa), and mean total precipitable water (wvp). Products are averaged to 2.5 degree lat × 2.5 degree long grids. 

Imagery
This dataset portrays monthly estimates of precipitable water (wvp), liquid water path (lwp), rainfall (pr1), and snow cover in both color and black and white. This domain of the SSM/I and SSMIS archive includes images of data from January 2006 to the present.

GPCP Input files
This time series domain of the SSM/I and SSMIS archive is formatted for the production of GPCP (Global Precipitation Climatology Project) datasets. The dataset is processed using early and late orbits plus a special "dual" orbit that combines the early and late satellite data. Products include rainfall (pr1 and pr2) and mean sampling fraction (ssa). The product is averaged to 2.5 degrees lat × 2.5 degrees long grids.

Binary
All data is also available in a legacy binary format, with the addition of a daily and pentad product. Products included in the daily domain are taken from early orbits and include: mean cloud fraction (cfr), mean sea-ice cover (ice), liquid water path (lwp), mean rain fraction (pf2), rainfall (pr1), snow cover fraction (snw), mean sampling fraction (ssa), and mean total precipitable water (wvp). Products are averaged to 1 lat x 1 long grids. Products included in Pentad domain are taken from specific satellite orbits and include: mean cloud fraction (cfr), mean sea-ice cover (ice), liquid water path (lwp), mean rain fraction (pf1 and pf2), rainfall (pr1 and pr2), snow cover fraction (snw), mean sampling fraction (ssa), and mean total precipitable water (wvp). Products are averaged to 2.5 lat x 2.5 long grids using 5-day estimates of rainfall and its frequency, cloud liquid water and cloud frequency, water vapor, liquid water path, snow cover frequency, satellite sampling frequency and various imagery. Pentad data only includes data from March 2008 to present.

For a complete description of these products, please refer to all associated documentation.