Relation between Cold Pool Areal Extent and Great Lake Ice Coverage

The annual maximum ice coverage (AMIC) on the Great Lakes has been decreasing in recent decades, with one estimate suggesting a loss of 71% over the period of 1973 to 2010. In addition, the AMIC varies greatly from year to year, impacting a broad range of stakeholders: local communities, recreational users, commercial shipping companies, and other economic interests. Improving our understanding of the causes of these annual variations will lead to subsequent improvements in the accuracy of seasonal AMIC forecasts, allowing stakeholders to more adequately plan for future conditions and their resulting impacts.

This research examined potential relationships between the variability in the areal extent of the lower-Tropospheric, wintertime cold pool (WCP) over the Great Lakes and the observed AMIC. WCP areal extent was based on area encompassed by the 850mb level -10°C, -5°C, and 0°C isotherms. This presentation focuses upon the relationship between WCP and AMIC, as well as the potential simultaneous influences of the El Nino Southern Oscillation, as well as the Arctic Oscillation, on the AMIC. Results from this work suggest that when using the -10˚C isotherm to define the WCP boundary, there is a statistically significant, positive linear relationship (α=0.05) between the areal extent of the WCP and the observed AMIC. Additionally, while there are statistically significant relationship between the areal extent of the WCP and the observed AMIC for different combinations of ENSO and AO phase, the sample sizes of these combinations are small and further analysis is necessary before any further conclusions can be drawn.