Great Lakes Ice Cover: Enriching Database and Improving Forecast

Abstract

Great Lakes ice cover has been regularly documented and reported only since the 1970s, while inconsistent records of ice cover began in the 1960s. These ice charts from the 1960s and early 1970s had yet to be digitized from physical prints and preliminary scans into a computer- and web-friendly format. Aerial surveys and satellite imagery of the ice cover started in the 1960s; there were very few records of Great Lakes ice cover before these surveys and ice charts began. Collection of weather data (temperature, wind, precipitation, etc.) began in the 1800s in the region, but ice cover reports were sparse and difficult to estimate. Using the surface air temperature data from 1897 to 1983, ice cover can be estimated and hindcasted back to the start of the weather record for the Great Lakes. Another atmospheric component that influences ice cover on the lakes is that of atmospheric teleconnections, such as the ENSO (El Niño Southern Oscillation), NAO (North Atlantic Oscillation), and newer ABNA (Asian-Bering-North American). While larger, more well-known teleconnections such as the ENSO and NAO have been analyzed next to Great Lakes ice cover, ABNA had yet to be compared to the lakes’ annual ice cover. These gaps in the collection of Great Lakes ice research were filled through this collaborative project between the University of Michigan School for Environment and Sustainability (SEAS) and NOAA’s Cooperative Institute for Great Lakes Research (CIGLR). The historical ice charts from 1963 to 1972 are now digitally available through the University of Michigan’s Deep Blue repository for this project; the Great Lakes’ ice cover has been hindcasted back to the winter of 1898, available here in Appendix II; and the ABNA has been recreated and statistically compared to the Great Lakes’ Annual Maximum Ice Cover (AMIC) values, and has proven to be a strong contender in forecasting and hindcasting ice cover on the Great Lakes. Great Lakes ice cover provides various ecosystem services in the Great Lakes, from tourism, to ice caves, to supporting the spawning of fish by protecting their eggs from wave action. At the same time, ice cover is a significant obstacle for winter navigation in the Great Lakes. Federal and commercial icebreaking operations are thus a vital aspect of wintertime shipping within the Great Lakes. Knowing ice conditions ahead of the winter season, or even with a longer lead time, is critical in planning in all these sectors. However, seasonal or longer forecasting of Great Lakes ice conditions has been challenging because of the strong year-to-year fluctuations in AMIC and little knowledge in what teleconnection pattern(s) influence the weather across the Great Lakes region. The deliverables of our project – the extended time series of AMIC, and identification of the ABNA as an important teleconnection pattern – well address these needs and provide a strong foundation to improve seasonal Great Lakes ice forecasting at NOAA Great Lakes Environmental Research Laboratory, the client of this project.