ISLSCP Initiative II | Related Pages |
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ISLSCP Initiative II Home General Data Overview Snow, Sea Ice, Oceans Data Overview |
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ISLSCP Initiative II |
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Snow, Sea Ice, & Oceans Data
This ISLSCP data set is derived from the National Snow and Ice Data Center (NSIDC) Northern Hemisphere EASE-Grid Weekly Snow Cover and Sea Ice Extent product which combines snow cover and sea ice extent at weekly intervals for October 1978 through June 2001, and snow cover alone from 1966 through June 2001. (Sea ice data were not available prior to October 23, 1978.) The original data set was the first representation of combined snow and sea ice measurements derived from satellite observations for the period of record. Designed to facilitate study of Northern Hemisphere seasonal fluctuations of snow cover and sea ice extent, the original NSIDC data set also includes monthly climatologies describing average extent, probability of occurrence, and variance
This data set shows the extent of snow on the land at a variety of scales (1 degree, 0.5 degrees, 0.25 degrees). The values represent the percentage of days in each month where snow was present -- 100 means 100% of the month, 80 means 80% of the month, etc. Missing data is represented by -99 for water and -88 for land.
This data was originally in a yearly tabular format. It was converted to multi-scale maps by plotting each point in the tabular data onto a map of -99 (water) and -88 (land) created from the standard ISLSCP II Land/Sea Masks.
Data Provider: Richard L. Armstrong, Mary Jo Brodzik
 Data Files (ISLSCP II Disc #1) |
 Data Set Documentation |
 Image Viewing Tutorial |
The files have been compressed using the PKZip program. Each file contains ASCII text at 1 degree (360 values per line, and 180 lines, labeled "1d"), 0.5 degrees (720 values per line, and 360 lines, labeled as "hd"), and 0.25 degrees (1440 values per line, and 720 lines, labeled as "qd"). Each line is terminated by a newline character. These values represent the percentage of days in that month where snow was present -- 100 means 100% of the month, 80 means 80% of the month, etc. Missing data is represented by -99 for water and -88 for land.
Each file name is image for a given month.
Example: snow_map_1d_19900900.asc contains the snow cover map at 1 degree for September 1990.
The data are structured so that the upperleft corner of the first pixel is located at 90 North latitude and 180 West longitude.
Related Pages:
ISLSCP Initiative II Home
General Data Overview
Snow, Sea Ice, Oceans Data Overview
Northern Hemisphere Snow Cover Extent
Revision Date: July 1, 2003