The Great Lakes Surface Environmental Analysis (GLSEA2) is a digital map of the Great Lakes surface water temperature and ice cover which is produced daily at the NOAA Great Lakes Environmental Research Laboratory (GLERL) in Ann Arbor, Michigan through the NOAA CoastWatch program. The GLSEA is stored as a 1024x1024 pixel map in PNG and ASC format, suitable for viewing on PCs and workstations with readily available software.
The lake surface temperatures are derived from NOAA AVHRR imagery obtained through the Great Lakes CoastWatch program. The addition of ice cover concentration 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 (details). Ice concentration will then be added, using the most recent Great Lakes Ice Analysis produced by NIC, historically twice per week during the ice season. Since 2011, the ice concentration data has been available on a daily basis.
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