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ISLSCP II Global Sea Ice Concentration
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Revision date: May 5, 2010


This International Satellite Land Surface Climatology Project (ISLSCP) Initiative II data set is based on the Goddard Space Flight Center (GSFC) Sea Ice Concentrations from Nimbus-7 Scanning Multichannel Microwave Radiometer (SMMR) and the Defense Meteorological Satellites Program (DMSP) Special Sensor Microwave/Imager (SSM/I) Passive Microwave Data. This data set contains four zip files which includes sea ice concentration (in percentage of ocean area covered by sea ice), table data and map data.  These original data were re-gridded by the National Snow and Ice Data Center (NSIDC) from their original 25-km spatial resolution and EASE-Grid into equal angle Earth grids with quarter, half and one degree spatial resolutions in latitude/longitude. The ISLSCP II staff have taken the one degree resolution original data provided by the Principal Investigator and created global maps of monthly sea ice concentration on a global one degree grid using the latitude and longitude coordinates that were provided. Individual monthly files were created and written to the ASCII format. The re-gridded one degree original data were also adjusted to match the one degree ISLSCP II land/water mask.

Additional Documentation:

This data set is one of the products of the International Satellite Land-Surface Climatology Project, Initiative II (ISLSCP II) data collection which contains 50 global time series data sets for the ten-year period 1986 to 1995. A complete description of the data, it's derivation, acknowledgements, and references provided by the ISLSCP II Data Management Staff is included with this data set as a companion file named 1_sea_ice_extent_doc.pdf.

ISLSCP II is a consistent collection of data sets that were compiled from existing data sources and algorithms, and were designed to satisfy the needs of modelers and investigators of the global carbon, water and energy cycle. The data were acquired from a number of U.S. and international agencies, universities, and institutions. The data and documentation have undergone two peer reviews.

ISLSCP is one of several projects of Global Energy and Water Cycle Experiment (GEWEX) [] and has the lead role in addressing land-atmosphere interactions -- process modeling, data retrieval algorithms, field experiment design and execution, and the development of global data sets.

Related Data Sets:

ISLSCP II Sea Surface Temperature

ISLSCP II Northern Hemisphere Monthly Snow Cover Extent

Data Citation:

Cite this data set as follows:

Armstrong, R.L. and K. Knowles. 2010. ISLSCP II Global Sea Ice Concentration. In Hall, Forrest G., G. Collatz, B. Meeson, S. Los, E. Brown de Colstoun, and D. Landis (eds.). ISLSCP Initiative II Collection. Data set. Available on-line [] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A. doi:10.3334/ORNLDAAC/981

File Information:

The archived data sets for ISLSCP II have been organized by categories. This data set is in the Snow, Sea Ice, and Oceans category-- a collection of snow, oceans, and sea ice data sets.

Data Set Spatial Extent: Global gridded

Westernmost Longitude: -180 W

Easternmost Longitude: 180 E

Northernmost Latitude: 90 N

Southernmost Latitude: -90 S

Projection: Geographic

Data Set Spatial Resolution: one, half, and quarter degree in both latitude and longitude

Data Set Temporal Extent: 1986 through 1995

Data File Format

All of the data files in each data set within the ISLSCP Initiative II data collection are in ASCII GRID format. The file format consists of numerical fields of varying length, which are delimited by a single space and arranged in columns and rows.

There are four data files (.zip files) in this data set which includes sea ice concentration (in percentage of ocean area covered by sea ice) data files, table data and map data,  at one degree (1d) half degree (hd) and quarter degree (qd) spatial resolution. There are 10 comma separated files (.csv) for each spatial resolution (10 years). See the file names and examples below: when extrapolated contains sea_ice_data_1d_1986.csv through  sea_ice_data_1d_1995.csv when extrapolated contains sea_ice_data_hd_1986.csv through sea_ice_data_hd_1995.csv when extrapolated contains sea_ice_data_qd_1986.csv through sea_ice_data_qd_1995.csv when extrapolated contains the files sea_ice_map_1d_YYYYMM00.asc, where YYYY is the year from 1986 through 1995 and MM is the month from 01 to 12. The "00" means that this is a monthly average. There are 120 files with the 1 degree gridded sea ice concentrations. This data zip file also includes  a "changemap or differences" file:sea_ice_changemap_1d.asc: gridded ASCII map showing the difference between the ISLSCP II land/water mask and the original data set. These files are in standard ESRI ArcGIS ASCII grid format.


Data file naming conventions are further described in the 1_sea_ice_extent_doc.pdf  and  0__sea_ice_extent_readme.txt.

Data Access:

These data are available through the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC) [].

Data Archive Contact Information:

Telephone: +1 (865) 241-3952