Near Real-Time SSM/I EASE-Grid Daily Global Ice Concentration and Snow Extent

Data Contributors

NOLIN, ANNE W.
ARMSTRONG, RICHARD
MASLANIK, JIM

Parameters

ICE EXTENT
SEA ICE CONCENTRATION
SNOW COVER

Instruments

SSM/I : SPECIAL SENSOR MICROWAVE/IMAGER

The Near Real-Time SSM/I EASE-Grid Daily Global Ice Concentration and Snow Extent product (Near real-time Ice and Snow Extent, NISE) provides daily, global near real-time maps of sea ice concentrations and snow extent. The National Snow and Ice Data Center (NSIDC) creates the NISE product using passive microwave data from the Defense Meteorological Satellite Program (DMSP) F13 Special Sensor Microwave/Imager (SSM/I). Sea ice concentration and snow extent maps are provided in two 25 km azimuthal, equal-area projections: the Southern Hemisphere 25 km low resolution (Sl) and Northern Hemisphere 25 km low resolution (Nl) Equal-Area Scalable Earth-Grids (EASE-Grids). Data are in Hierarchical Data Format - Earth Observing System (HDF-EOS) format and browse files are in GIF and HDF formats, and are updated daily and are available via FTP and the Data Pool. Users can also order HDF-EOS data files from 04 May 1995 through present via the Web-based Earth Observing System (EOS) Data Gateway.

Sea ice concentrations are mapped using the NASA Team algorithm. Snow extent is mapped separately using an algorithm developed for Scanning Multichannel Microwave Radiometer (SMMR) data and modified for use with SSM/I data (Chang, Foster, and Hall 1987; Armstrong and Brodzik 2001). The NISE product is updated daily using the best available data from the past five days. NASA provided funding for the production of this data set through the NSIDC Distributed Active Archive Center (DAAC).

All algorithms are subject to change in order to provide the best possible snow and ice mapping capabilities. Snow extent derived from passive microwave satellite data is a product that is constantly undergoing revision and improvement at NSIDC. 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.

NSIDC requests that prospective data users explain how the data will be used and agree to contribute comments regarding the usefulness, relevance, and accuracy of the data. Such feedback is essential to ensure ongoing product improvement. Publication of research results must appropriately acknowledge use of the NISE product.

Data Citation

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, publishers (NSIDC), and digital media.

Nolin, A., R.L. Armstrong, and J. Maslanik. 1998, updated daily. Near Real-Time SSM/I EASE-Grid Daily Global Ice Concentration and Snow Extent, January to March 2004. Boulder, CO, USA: National Snow and Ice Data Center. Digital media.