NOAA PUBLISHES ELECTRONIC GREAT LAKES ICE ATLAS

Oct. 22, 2003 — To some of us, ice is nothing more than a clear cube of frozen liquid that we use to cool our beverages, but to people and creatures who live in and around lakes, it is part of the ebb and flow of their daily life. NOAA published a new 30-year electronic atlas of ice cover for the Great Lakes. The atlas contains data on more than 1,200 digitized Great Lakes ice charts for winters from 1973 to 2002 and an analysis of these ice charts. (Click NOAA image for larger view of ice formation in the St. Joseph channel of Lake Michigan taken on Feb. 18, 2000. Please credit “NOAA.”)

Ice is nice, but who would use such a collection of information? A lot of people, explained Raymond Assel, a physical scientist at the NOAA Great Lakes Environmental Research Laboratory in Ann Arbor, Mich., who, along with others, spent a decade working on this project.

“The atlas is a resource for those seeking information on Great Lakes ice cover climatology. It provides a benchmark of ice cover and ice cover variation of the Great Lakes during the last quarter of the 20th century and early years of the 21st century,” he said. (Click (Click NOAA image for larger view of ice chart from March 25, 2002, showing parts of the Great Lakes under 100 percent of ice cover. Please credit “NOAA.”) Please credit “NOAA.”)

Assel added that the Navy/NOAA National Ice Center and the Canadian Ice Service use information from this atlas in making operational Great Lakes ice charts. Portions of these data have also already been used by other federal and state government agencies, academia and the private sector for research, educational, operational and engineering applications.

People who are involved in fisheries studies know that ice cover is an important factor in the life cycle of certain fish species; people who model lake levels know that more ice cover means less evaporation; Great Lakes shippers, the U.S. Coast Guard and the Army Corps of Engineers need to know ice conditions for planning and for operational activities in winter and early spring; and river ice jams in the connecting channels of the Great Lakes can cause damage to shore property and loss of hydroelectric generating capacity, Assel said.

“Also, people who enjoy ice fishing want to know when the bays and harbors freeze over,” he said.

The atlas offers three types of analysis products.

• 1) Ice charts dates of the first reported ice, dates of the last reported ice, and ice duration for each winter, as well as statistics over the 30-winters—the maximum, minimum and average;
• 2) A 30-winter set of 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 lake-averaged ice cover for each lake over the 30 winters;
• 3) Weekly ice charts 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 data set and not on the daily time series.

The atlas contains a lot of information—1.4 gigabytes of data, much of which is in compressed files (about 4 gigabytes when uncompressed). The online version of this atlas can be used to browse and download a limited amount of data.

However, because of its large size, it is not practical to download the entire atlas from the Internet. Therefore, it is also available on CD-ROM and DVD formats. To request a copy of the atlas on CD-ROM or DVD send an e-mail to Cathy.Darnell@noaa.gov or to iceatlas.glerl@noaa.gov.
(Please provide your name and complete mailing address.)

NOAA is dedicated to enhancing economic security and national safety through the prediction and research of weather and climate-related events and providing environmental stewardship of the nation�s coastal and marine resources. NOAA is part of the U.S. Department of Commerce.

Relevant Web Sites
NOAA Great Lakes Environmental Research Laboratory

NOAA Research

Media Contact:
Jana Goldman, NOAA Research, (301) 713-2483