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Great Lakes Ice Cover


Understanding the major effect of ice on the Great Lakes is crucial because it impacts a range of societal benefits provided by the lakes, from hydropower generation to commercial shipping to the fishing industry. The amount of ice cover varies from year to year, as well as how long it remains on the lakes. GLERL scientists are observing long-term changes in ice cover as a result of global warming. Studying, monitoring, and predicting ice coverage on the Great Lakes plays an important role in determining climate patterns, lake water levels, water movement patterns, water temperature structure, and spring plankton blooms.

NOAA-GLERL has been exploring the relationships between ice cover, lake thermal structure, and regional climate for over 30 years through development, maintenance, and analysis of historical model simulations and observations of ice cover, surface water temperature, and other variables. Weekly ice cover imaging products produced by the Canadian Ice Service started in 1973. Beginning in 1989, the U.S. National Ice Center produced Great Lakes ice cover charts that combined both Canadian and U.S. agency satellite imagery. These products are downloaded at GLERL by our Coastwatch program, a nationwide NOAA program within which the GLERL functions as the Great Lakes regional node. In this capacity, GLERL obtains, produces, and delivers environmental data and products for near real-time observation of the Great Lakes to support environmental science, decision making, and supporting research. This is achieved by providing access to near real-time and retrospective satellite observations and in- situ Great Lakes data.

Current Ice Cover Conditions

Coastwatch and GLSEA

CoastWatch is a nationwide National Oceanic and Atmospheric Administration (NOAA) program within which the Great Lakes Environmental Research Laboratory (GLERL) functions as the Great Lakes regional node. In this capacity, GLERL obtains, produces, and delivers environmental data and products for near real-time observation of the Great Lakes to support environmental science, decision making, and supporting research. This is achieved by providing access to near real-time and retrospective satellite observations and in-situ Great Lakes data.

GLSEA (The Great Lakes Surface Environmental Analysis) is a digital map of the Great Lakes surface water temperature and ice cover which is produced daily at GLERL.The lake surface temperatures are derived from NOAA polar-orbiting satellite imagery. The addition of ice cover information was implemented in early 1999, using data provided by the National Ice Center (NIC). Lake surface temperatures are updated daily with information from the cloud-free portions of the previous day's satellite imagery. If no imagery is available, a smoothing algorithm is applied to the previous day's map.

Graphs of Percent Ice Cover By Month for the Current Season:

Superior
Michigan
Huron
Erie
Ontario






See also:


Additional Resources:

Environment Canada Daily Great Lakes Ice Charts

National Ice Center data


Contact:

George Leshkevich
NOAA/GLERL - Coastwatch
4840 S. State Rd.
Ann Arbor, MI 48108-9719

734-741-2265

Historical Ice Cover

NOAA/GLERL has been monitoring and documenting Great Lakes ice cover since the early 1970's using the ice products developed by the U.S. National Ice Center and the Canadian Ice Service. Research conducted on hydrometeorological processes and regional climate trends has led to models of lake thermal structure that play an integral role in ecosystem forecasting.

Plots of Historical Ice Cover (click each chart to enlarge):








Great Lakes Ice Atlas: The original ice chart data set consists of over 1200 digitized ice charts. These ice charts display observed ice cover over each Great Lake throughout every winter season from 1973 to 2002. Additions to the ice atlas for 2003-2011 are here: http://www.glerl.noaa.gov/data/pgs/glice/glice.html

There are three analysis products. The first product includes ice charts of the following: dates of the first reported ice, dates of the last reported ice, and ice duration for each winter, as well as, the maximum, minimum and average ice cover concentrations. The second product is the 30-year annual daily ice cover time series. The daily time series was used to create: 1) computer animations of spatial patterns of ice cover for each winter, 2) line plots of lake averaged ice cover for each lake over the 30 winters. 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 data set and not on the daily time series.

Recent Great Lakes Ice Cover Data: (2003-2013) The Great Lakes Ice Atlas is a stand-alone product that documents Great Lakes ice conditions from 1973-2002. This page extends that time series through 2013 (though only grid files are available for 2012 and 2013 at this time). For each year, three types of products are available: original ice charts from the National Ice Center (ASCII files), graphic images of ice maps (jpg files) and ArcGIS feature classes for GIS users (shapefiles).

Historical Ice Data Sets and Resources:


Contact:

Jia Wang
NOAA/GLERL - Ice-Climate Modeling/Forecasting
4840 S. State Rd.
Ann Arbor, MI 48108-9719

734-741-2281

Ice Cover Forecasting

GLERL conducts research on ice cover forecasting on two different time scales: short-term (1-5 days) and seasonal. GLERL's short-term ice forecasting is part of the Great Lakes Coastal Forecasting System, an operational model used by the National Weather Service to predict wind, waves, currents, and more. The ice nowcast and forecast products (concentration, thickness, velocity, and vessel icing) are still experimental. GLERL's seasonal ice cover forecast is based on statistical and physical analysis. This forecast is also experimental.

Short-term Ice Forecasting (1 to 5 days)

The Great Lakes Coastal Forecasting System (GLCFS) is a short-term physical modeling framework for predicting waves, currents, water temperature, and ice. GLCFS water temperature, air temperature, wind, and the National Ice Center daily ice cover are used to predict ice concentration (%) up to 5 days in the future. Ice forecast products under development include ice thickness, vessel icing, and ice velocity.

The following links to the Great Lakes Coastal Forecasting System pages which contain visual summaries of current Great Lakes ice conditions.

These links to the GLCFS Nowcast/Forecast pages include current observed ice cover, wind, and air temperature as well as model-derived ice thickness, ice velocity, vessel icing, surface currents, and water temperature. Forecast and animations for all parameters are available for up to 5 days. Note that some of these products are still under development.

Superior
Michigan
Huron
Erie
Ontario






Seasonal Ice Cover Forecasting

Research at GLERL has shown that the interannual variability of Great Lakes ice cover is heavily influenced by two large-scale climate drivers: ENSO (El Nino and Southern Oscillation) and NAO (North Atlantic Oscillation) or AO (Arctic Oscillation). Based on statistical and physical analysis, regression models were developed linking climate indices (ENSO and NAO) and annual maximum ice coverage for each of the Great Lakes as well as for the basin. Using the projected ENSO and NAO indices, a seasonal forecast for Great Lakes ice cover can be made. This is an area of active research at GLERL.

Contact:

Eric Anderson
NOAA/GLERL - Short-term forecasting
4840 S. State Rd.
Ann Arbor, MI 48108-9719

734-741-2293

Jia Wang
NOAA/GLERL - Ice-Climate Modeling/Forecasting
4840 S. State Rd.
Ann Arbor, MI 48108-9719

734-741-2281

Great Lakes Ice Cover - Frequently Asked Questions

What is the current state of ice cover for the Great Lakes Basin?

Click here to view a map displaying the current extent of ice cover as observed by NOAA Coastwatch's Great Lakes Surface Environmental Analysis (GLSEA)

How does 2014 ice cover compare with previous years (1973-2013)?



For a retrospective, see this article in EOS, Transactions, from the American Geophysical Union (August 2014).

When was ice cover the highest (or lowest) for each of the Great Lakes?

View the records* for Great Lakes Annual Ice Cover (percent) from 1973-2013 below:

Highest Annual Maximum Ice Cover (%)
Year
Lowest Annual Maximum Ice Cover (%)
Year
Basin 94.7 1979 11.8 2002
Superior 100 1996 8.2 2012
Michigan 93.1 1977 12.4 2002
Huron 98.5 1994 23.1 2012
Erie 100 1978, 1979, 1996 5.4 1998
Ontario 86.2 1979 1.9 2012

*See Table 1 from: ASSEL, R.A., J. WANG, A.H. CLITES, and X. BAI. Analysis of Great Lakes ice cover climatology: Winters 2006-2011. NOAA Technical Memorandum GLERL-157. NOAA Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 26 pp. (2013). http://www.glerl.noaa.gov/ftp/publications/tech_reports/glerl-157/tm-157.pdf

Do we have evidence that Great Lakes ice cover is declining?

The Great Lakes ice cover data set is relatively short: 1973 to present. However, averaging the ice cover data for each lake for different 20-year time periods does reveal a downward trend in ice cover:

Why does Lake Ontario generally have the least ice cover of all the Great Lakes?

Lake Ontario's extreme depth (86 m average; 244 m maximum) translates to tremendous heat storage capacity. It also has a smaller surface area for heat loss. In addition, cold air outbreaks from the northwest and west are moderated by the waters of Lakes Superior, Michigan, and Huron. These factors combine to keep ice cover on Lake Ontario at a relatively low level most years.

When does ice cover peak on the Great Lakes?

Maximum ice cover on the lower lakes (like Lake Erie) normally occurs between mid-February and end of February. Maximum ice cover on the upper lakes (like Lake Superior) normaly occurs between end of February and early March.

Does more ice cover reduce evaporation and lead to higher water levels?

The relationship between ice cover, evaporation, and water levels is complex. Data on modeled evaporation shows that this process peaks in the fall, before ice cover formation. In a severe ice cover year such as 2014, the thermal structure of the lake could be impacted for the rest of the year, potentially reducing evaporation from the lakes next fall. Evaporation and precipitation are the major drivers of seasonal water level changes in the Great Lakes.

Does more ice now mean cooler water temperatures this summer?

Ice extent plays a part in determining water temperature in the lakes later in the year, as incoming heat will have to melt the ice before it warms the water below. However, meteorological conditions and heat storage in the lakes are also critical components to the thermal cycle in the lakes.