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SSM/I Enhanced Resolution Image Products

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) www.remss.com.

Available Image Classes
  SIR file name prefix
evening passes Fe3
morning passes Fm3
Images are produced in the BYU .SIR file format using the standard naming scheme. The files are gzipped to minimize storage and transfer requirements. The standard images are designed for land and ice observation. Data over the ocean is generally not useful. However the distributed images are not land masked. .SIR format land mask files (containing 0 for ocean and 1 for land) are available for each standard region. .SIR format images containing "images" of the latitude and longitude of each pixel for each region are also available. The image pixel nominal resolution is 8.9 km/pixel, except for the 85 GHz channels which have pixel resolution of 4.45 km/pixel.

Citation information:
Images are courtesy of David G. Long at the Scatterometer Climate Record Pathfinder Project from the version 7 SSM/I data record produced by Remote Sensing Systems under the direction of Frank Wentz.

D.G. Long and D.L. Daum, "Spatial Resolution Enhancement of SSM/I Data," IEEE Transactions on Geoscience and Remote Sensing, Vol. 36, No. 2, pp. 407-417, Mar. 1998.
D.S. Early and D.G. Long, "Image Reconstruction and Enhanced Resolution Imaging from Irregular Samples," IEEE Transactions on Geoscience and Remote Sensing, Vol. 39, No. 2, pp. 291-302, 2001.


Note: the National Snow and Ice Data Center (NSIDC) hosts a comprehensive set of enhanced resolution radiometer brightness temperature products from SSM/I, SMMR, SMMIS, and AMSRE that were produced using SCP techniques for the Calibrated Passive Microwave Daily Equal-Area Scalable Earth (EASE) Grid~2.0 Brightness Temperature (CETB) Earth System Data Record (ESDR) project.