Evaluating the Response of the Labrador Sea to Greenland Meltwater Influx With High-Resolution Eddy-Rich NEMO Simulations

Abstract

The Greenland Ice Sheet has undergone substantial mass loss in recent decades primarily due to oceanic and atmospheric warming, contributing to global sea-level rise and enhanced ocean stratification. This study examines the Labrador Sea's response to increased Greenland freshwater influx using a very high-resolution, eddy-rich configuration of the NEMO ocean model. Two 9-year long experiments with identical setups, except one excluding Greenland runoff, suggest that freshwater influx leads to freshwater content increase (by up to 39%) and intensified stratification (enhanced convective resistance by up to 29%) in the Labrador Sea, whereas heat content remains mainly unchanged (up to 6% increase). Strengthened stratification weakens but does not entirely stop deep convection allowing continued water mass formation within the region (maximum mixed layer depth differences of up to 635 m). A sensitivity analysis indicates warmer, saltier surface waters and colder, fresher subsurface layers when Greenland meltwater is excluded likely driven by reduced lateral exchange from the West Greenland Current system and enhanced southward Arctic Water transport across Davis Strait. Offshore freshwater exchange in the Labrador Sea interior is not solely controlled by Greenland meltwater influx but also by air-sea fluxes and deepwater formation. Over longer timescales exceeding a decade, ongoing freshening and intensified stratification could further disrupt essential oceanic processes with potential consequences for deepwater formation and Atlantic Meridional Overturning Circulation. These findings underscore the importance of accurately representing Greenland meltwater and shelf-basin exchanges in models to improve the predictions of Labrador Sea under future warming.