Monitoring lake ice freeze-up and break-up provides a useful seasonally-integrated index of climatic change. Manual observations of lake freeze-up and break-up (phenology) have been made at an extensive network of Canadian sites since the 1800s. These data have been used in several studies, both to identify trends in the ice cover and to validate model and remote sensing results. The Canadian network has decreased substantially in recent years, and increasing use is being made of satellite data, particularly NOAA AVHRR and RADARSAT, to monitor lake ice cover. Investigations to use passive microwave are being undertaken. The advantage of satellite data is that it provides a complete image of lake ice cover, unlike manual observations which are limited to the local scale. Satellite data also allows lake ice monitoring to be carried out over vast uninhabited areas of Canada, thus providing useful climate information in areas without surface-based observations. The increasing resolution of climate and weather forecast models has also created a need for regular monitoring of lake ice coverage from satellite data - the amount of open water has a major impact on regional-scale processes such as lake-effect snowfall.
The Canadian Ice Service (CIS) monitors more than 130 Canadian and northern US lakes via remote sensing on a regular basis. Ice coverage is measured in tenths, and from this the freeze-up and break-up dates can be determined within a ±one week accuracy.
The interactive Lake Ice tool below shows freeze and thaw dates for a large selection of Canadian and US lakes from 2004 to the present. Red dots signify a lack of data for the lake at the specified date. Also note that ice thickness data for three lakes can be viewed in the ITCN visualization.
Another method for monitoring lake ice is with a digital camera, e.g. Brown and Duguay (2011). This method can be used for lake ice monitoring in unattended locations to examine the seasonal change in the ice cover. An example of lake ice break-up occurring on Malcolm Ramsay Lake (near Churchill, MB) is shown in the video below.