Great Lakes Ice Charts With Weekly Extent Data

Great Lakes Ice Charts, Version 1 contains annotated chart images showing ice extent and concentration three times weekly during the ice season for all lakes except Ontario. The dataset spans 28 ice seasons from 1973/74 through 2001/2002 and was prepared by the National Weather Service Forecast Office and later the National Ice Center. Charts are available as GIF files and include insets for specific areas like the Straits of Mackinac.

Use Cases

• Analyzing long-term trends in Great Lakes ice coverage using the annotated extent charts.
• Studying seasonal ice concentration variability across different lake basins.
• Validating satellite-derived ice products against historical, manually prepared chart data.
• Examining ice conditions in specific sub-regions like Green Bay using the provided inset charts.

Strengths

• Provides a long temporal record covering 28 consecutive ice seasons from 1973 to 2002.
• Charts are annotated with data sources, offering transparency on observation methods.
• Features high spatial detail with separate charts and insets for key areas like the Straits of Mackinac.
• Data collection frequency is high for ice studies, with charts produced three times weekly.

Limitations

• The dataset format is GIF image files, requiring manual digitization or image analysis for quantitative use.
• Platforms disagree on the last update date, with one source listing 2002 and another listing 2026, creating uncertainty about metadata maintenance.
• Lake Ontario is explicitly excluded from the chart series, limiting complete basin-wide analysis.

Provenance

Source

National Ice Center (formerly Navy/NOAA Joint Ice Center) and National Weather Service Forecast Office, Ann Arbor.

Collection Method

Manually prepared ice charts based on observational data sources, annotated and released as GIF files.

Time Range

1973/74 ice season through 2001/2002 ice season.

Freshness

Data collection ended with the 2001/2002 ice season; the most recent platform update is listed as 2026-03-13, but this likely reflects metadata revision, not new data.

Geography

Great Lakes region (Superior, Michigan, Huron, Erie), excluding Lake Ontario.