The Special Sensor Microwave Imager has seven passive channels consisting of
the channels: 19 GHz V- and H-polarization, 22 GHz V-polarization, 37 GHz V- and H-polarization,
and 85 GHz V- and H-polarization.
The spatial resolution of the data varies with frequency, with 19 GHz being the
coarsest and 85 GHz having the finest resolution. The high frequency channels
are designed for atmospheric observation, but can have utility for land and ice surface
observation if the atmospheric "interference" can be tolerated.
Daily enhanced resolution brightness temperature (Tb) images are generated for
each frequency and polarization based using the radiometer version of the
Scatterometer Image Reconstruction (SIR) algorithm (Long and Daum, 1998). Since there can be a wide
time-of-day effect on Tb, twice daily images are created based on the local time-of-day
of the passes. Generally, the local time-of-day of the data has a narrow window
(one or two hours, though the polar regions can have a larger span). Note that
changes in Tb between multiple passes can result in imaging artifacts, which typically
appear as noise-like regions.
The SSM/I image grids and projections are compatible with, and identical to, other SCP
image grids. Two image resolutions are used: one for the lower
frequency channels, with a finer resolution used for the 85 GHz frequency channels. The
Images are generated from version 7 of the F13 SSM/I data record produced by Remote Sensing Systems (RSS)