Read Me File
NOAA Great Lakes Ice Atlas

August 2003

This Read Me file provides information for using the NOAA Great Lakes Ice Atlas Web site, CD-ROM, and DVD-ROM. This publication is an official NOAA Atlas. The Web site version of the NOAA Great Lakes Ice Atlas will be updated from time to time as new ice cover information and new publications become available. This will not be the case with the CD because of space limitations. However, the updated Web site will be available on an updated DVD. The CD and DVD contain the entire web site content as of August 2003.


Dataset and Analysis Products
Original Ice Charts. The original ice chart dataset consists of over 1200 digitized ice charts. These ice charts display observed ice cover over each Great Lake for every winter season from 1973 to 2002.

Analysis Products. There are three analysis products. The first product includes ice charts and ASCII grids of dates of first ice, dates of last ice, and ice duration for each winter season. In addition, there are ice charts that portray the composite maximum and minimum and a 30-winter average of each of these variables.

The second product is the 30 annual daily ice cover time series. The daily time series was used to create: computer animations of spatial patterns of ice cover for each winter and line plots of the daily lake averaged ice cover for each lake, for each of the 30 winter seasons.

The third product is weekly statistics. There are weekly ice charts and grids of: maximum, 3rd quartile, median, 1st quartile, and minimum ice cover concentrations for the 30-winter base period. The weekly statistics are based on the original ice chart dataset and not on the daily time series.

Operating the CD-ROM / DVD-ROM

The CD / DVD is compatible with Windows, Macintosh, Linux, and Unix operating systems. On most Windows machines, the Ice Atlas homepage will open automatically, once the CD / DVD is loaded into the drive. If the homepage does not open automatically, simply double-click the index.html file located at the root level. It will launch in your default browser application (such as Netscape or Internet Explorer). The interface may be navigated as if it were online.

External links to other Web sites will not function without Internet access. You can quickly ascertain whether you are operating from the CD / DVD or the Internet by reading the URL. The CD / DVD pages have an address beginning with <file:///>, while the online pages begin with <http://>.

Technical Information

Downloadable Documents
A number of documents are available on the NOAA Great Lakes Ice Atlas in Portable Document Format (PDF). These files can be viewed using Adobe Acrobat Reader. A free copy of Adobe Acrobat Reader can be downloaded from: <>.

Advanced Features (Animations, Zipped files)
To view .AVI animation files: any media application capable of playing ".avi", such as Microsoft Windows Media Player, or Real Player may be used. To view .FLC animation files: any media application capable of playing ".flc", such as QuickTime, may be used. Free copies of these applications can be downloaded: Quicktime from<>; Windows Media from <>; or Real Player from <>.

The atlas includes files that were compressed using WinZip. They are identified by the .zip extension. To open .zip files: a Zip compression utility such as PKUNZIP, WINZIP, Stuffit Expander (Macintosh), or almost any other compression utility can be used to uncompress them. Note: these files were originally created and compressed on a Windows platform. Please be aware that formatting errors may occur if uncompressed using a non-Windows platform.

Editorial Policy

The NOAA Great Lakes Ice Atlas is managed by the National Oceanic and Atmospheric Administration's Great Lakes Environmental Research Laboratory (GLERL), U.S. Department of Commerce. As a federal government site, all federal editorial policies apply, such as those on privacy, copyright, commercial
promotion, etc.

Information presented on the web site, CD-ROM, and DVD is considered public information and may be distributed freely. If you elect to use any of the materials (graphs, ice charts, ASCII files, ARC/Info files, or text), please use the citation given below, and include the appropriate URL of the page(s) from which the materials were taken. Updated versions of this Atlas may include additional authors.

Assel, R.A. 2003. An Electronic Atlas of Great Lakes Ice Cover. NOAA Great Lakes Ice Atlas, Great Lakes Environmental Research Laboratory, Ann Arbor, Michigan 48105. [Available over the Internet at:… ]


The NOAA Great Lakes Ice Atlas is maintained by the NOAA's Great Lakes Environmental Research Laboratory (GLERL) U.S. Department of Commerce. NOAA makes no warranty regarding these data, expressed or implied, nor do the fact of distribution constitute such a warranty. NOAA and GLERL cannot
assume liability for any damages caused by any errors or omissions in these data, nor as a result of the failure of these data to function on a particular system.

The appearance of external links on the web site, CD-ROM, or DVD does not constitute endorsement by the U.S. Department of Commerce or the National Oceanic and Atmospheric Administration of the external Web sites or the information, products, or services contained within. For other than authorized activities, the U.S. Department of Commerce and the National Oceanic and Atmospheric Administration do not exercise any editorial control over the information you may find at these locations.

Specific products and manufacturers are mentioned in certain areas of the NOAA Great Lakes Ice Atlas. Mentions of these products or manufacturers do not constitute an endorsement by NOAA or the U.S. Department of Commerce.


This work was funded in part by NOAA’s Earth System and Data Information Management program. The NIC and the CIS provided the historic ice charts. Mr. David Norton's (NOAA GLERL) contributions during the data reduction and quality control phases of this project were critical for its successful completion. University of Michigan’s Cooperative Institute for Limnology and Ecosystems Research (CILER) staff; D. Meyers, B.A. Hibner, N. Morse, P.J. Trimble, K. Cronk, and M. Rubens and GLERL staff; Ms. Deborah Lee, provided invaluable contributions to this project. Ms. Janet Szczesny (CILER), Ms. Cathy Darnell, and Mr. Gregory Lang (NOAA GLERL) were instrumental in the development of the GUI.

This is GLERL Contribution Number 1266.

Contact Information

NOAA Great Lakes Environmental Research Laboratory (GLERL)
2205 Commonwealth Blvd.
Ann Arbor, MI 48105-2945

Phone: (734) 741-2235