Projected Changes of Water Currents and Circulation in Lake Michigan Under Representative Concentration Pathways Scenarios

Abstract

AbstractThe Great Lakes’ atmosphere predominantly signposts signatures of climate change in terms of an elongated summer, depletion of ice‐cover, and up‐surging lake surface temperature and air temperature, which demands an in‐depth comprehension of future lake circulation dynamics. After satisfactory validations for the lake meteorology and hydrodynamics during 2010–2019, historical and future predictions based on a downscaled climate model for the Great Lakes region under Representative Concentration Pathways (RCP) 4.5 and 8.5 scenarios are used to drive the Finite‐Volume Community Ocean Model applied to Lake Michigan during the ice‐free months of 2010–2069. Substantial rises in lake surface current speed during May–June and September–October are connected to the rising wind speed and air temperature in the lake domain. Under the RCP 4.5 scenario, the study expects a 6.5% per decade relative increase in surface current speed, with a rise of 1.3% in the coastal circulation (within 50‐m depth from the coast) until 2050. Surface circulation strength can reach the highest rise (13%) during 2030–2039 and a slight drop (−1%) during 2050–2069. During May–December, only a 0.3% variation is predicted in current magnitudes under RCP 4.5 and 8.5 scenarios. The projections anticipate the occurrence of a stronger, wider, and northward shifting lake gyre with changing lake meteorology. Further analysis indicates that the reduced thermal gradient over the lake surface tends to resist sharp modulations in winds and lake dynamics in the successive decades.