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Near Real-Time DMSP SSM/I Daily Polar Gridded Brightness Temperatures

Summary

The Near Real-Time DMSP SSM/I Daily Polar Gridded Brightness Temperature product provides brightness temperatures (T_Bs) for both the Northern and Southern Hemispheres. These T_Bs are used to generate near real-time sea ice concentrations. Near real-time passive microwave T_Bs from the Defense Meteorological Satellite Program (DMSP) F13 Special Sensor Microwave/Imager (SSM/I) are received daily from the Marshall Space Flight Center and gridded onto the SSM/I polar stereographic grid. Two-byte scaled integer data are available via ftp at a resolution of 25 km for the 19, 22 and 37 GHz channels, and at 12.5 km resolution for the 85 GHz channels. NSIDC plans daily updates to the data. These data will be retained on the ftp site until NSIDC's standard T_B product, the DMSP SSM/I Daily Polar Gridded Brightness Temperatures, is available.

Typically, NSIDC receives the standard SSM/I T_Bs from Remote Sensing Systems, Inc. (RSS), who derive them from SSM/I antenna temperatures, between three and six months after the initial satellite overpass. NSIDC chose to provide near-real time T_Bs to facilitate time-sensitive research dependant upon precise detection of seasonal polar sea ice formation and break up.

Daily T_Bs consist of seven files, one for each channel and polarization, for each hemisphere.

Possible differences between the standard and near-real time products remain to be determined. The near-real time data do not supplant the standard products, but instead fill the gap in time between present-day and the delivery of the RSS data. Users are therefore cautioned to be aware of potential data differences, and should continue to use the standard products derived from the RSS data for time series analyses.

These data are not suitable for time series, anomalies, or trends analyses. They are meant to provide a best estimate of current ice and snow conditions based on information and algorithms available at the time the data are acquired. Near real-time products are not intended for operational use in assessing sea ice conditions for navigation.

Near-real time data will remain on-line and available to users for three months after receipt of NSIDC's standard products from RSS. The file naming convention allows users to easily distinguish the near-real time data from the standard SSM/I T_Bs.

For general information about these data, please see the DMSP SSM/I Daily Polar Gridded Brightness Temperatures. Users interested in understanding how the near-real time data were acquired and processed should review Near Real-Time SSM/I EASE-Grid Daily Global Ice Concentration and Snow Extent.

Document Information

Document Revision Date: 27 May 1999
Document Review Date: June 1999
Document ID: nsidc-0080

Citation:

To broaden awareness of our services, NSIDC requests that you acknowledge the use of data sets distributed by NSIDC. Please refer to the citation below for the suggested form, or contact NSIDC User Services for further information. We also request that you send us one reprint of any publication that cites the use of data received from our Center. This helps us to determine the level of use of the data we distribute. Thank you.

The following example shows how to cite the use of this data set in a publication. List the principal investigators, year of data set release, data set title, dates of data you used, publisher (NSIDC), and digital media.

Cavalieri, D., P. Gloerson, and J. Zwally. 1999, updated daily. Near real-time DMSP SSM/I daily polar gridded brightness temperatures, [dates used]. Edited by J. Maslanik and J. Stroeve. Boulder, Colorado USA: National Snow and Ice Data Center. Digital media.